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Fish Report

This document discusses the health effects of omega-3 fatty acids from fish oils versus plant sources. It notes that while fish oils are often promoted for their heart and brain benefits, the evidence is inconclusive and fish can contain harmful pollutants like mercury and PCBs. Plant-based sources of omega-3s like flaxseeds, chia seeds, and walnuts do not contain these toxins and may provide the same health benefits without risk. The document recommends public health policies promote plant omega-3s over fish oils for better health and sustainability.

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THE fish report Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils A scientific report by Dr Justine Butler, Senior Health Campaigner Vegetarian & Vegan Foundation, Top Suite, 8 York Court, Wilder Street, Bristol BS2 8QH. Tel: 0117 970 5190 www.vegetarian.org.uk
2 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils By: Dr Justine Butler, Senior Health Campaigner, Vegetarian & Vegan Foundation (VVF) Find more information at www.vegetarian.org.uk/campaigns/fish Published by: Vegetarian & Vegan Foundation, Top Suite, 8 York Court, Wilder Street, Bristol BS2 8QH T: 0117 970 5190 E: info@vegetarian.org.uk W: www.vegetarian.org.uk © The Vegetarian & Vegan Foundation 2009. Registered charity 1037486
3 Contents 4 Introduction 22 Contaminated fish are a danger to health 22 POP goes the seawall 5 An introduction to fat 22 PCBs 5 Why do we need fat? 23 Dioxins 5 The chemical structure of fat 23 Mercury rising 7 Getting to know the EFAs 24 Food Poisoning 7 How much fat? 24 Fish and PhIPs 8 Oily fish 25 Farmed and dangerous 8 How much oily fish? 8 EFA deficiency 26 Fish oil supplements 9 Balancing the fat 9 Optimising conversion 26 The official position – not budging 11 Omega-3s from algae – cut out the middleman 27 Plant EFAs leading the way to good health 11 Oily fish, EFAs and health 11 Heart health 27 Sustainability 14 Inflammatory diseases 15 Arthritis 28 Recommendations 17 Multiple sclerosis 19 Allergies 28 Conclusion 20 Brain food 21 Fish oils for brainy kids? 29 References
4 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils Introduction However, it also continues to recommend we eat oily fish. The mixed messages have left people understandably Over the last decade or so, the reputation of fish oils has confused. undergone a meteoric rise from the dreaded cod liver oil of years gone by to the highly esteemed omega-3 fish oil Farmed fish are not the answer. In general they tend to capsules of the new millennia. If you want to keep up with contain less omega-3s than their wild counterparts and modern nutrition you must be omega-3 savvy! more toxins. In fact, the levels of toxins in farmed fish are a significant concern to many scientists. A comparison of The alternative view is that the only thing ‘clever’ about fish farmed salmon and wild salmon found that the farmed fish oils is the huge marketing campaign that has got thousands had consistently higher levels of contaminants, including of people running to the health food shops. Fish oils are PCBs. Other studies show similar findings. This could promoted everywhere you look – well-known scientists mean considerable health risks for those who regularly recommend them for children, TV adverts hint at their eat farmed salmon. brain-boosting benefits, food producers slip them into all manner of foods. Health food shops struggle to meet Fish is not a popular food in the UK; people eat only a third demand. So convincing is the marketing that many people of a portion of oily fish a week with seven out of ten people believe that oily fish are the only source of the magical consuming none at all. Promoting oily fish as a public health omega-3 fatty acids which keep our hearts healthy, children policy is clearly not working. The worst consequence of this clever and ward off allergies and inflammatory conditions is that more helpful advice on how to get omega-3s from such as arthritis. plant-based foods is just not being given. We’re told that oily fish benefit heart health because of The good news is you don’t have to eat neurotoxins and the omega-3 fats they contain. However, the evidence carcinogens to get your omega-3s; there are perfectly safe is inconclusive. One long-term study showed that men plant sources. Many studies show that omega-3s from plants with heart disease, advised to eat oily fish or fish oil can protect health without exposing us to these harmful supplements, had a higher risk of sudden death from heart toxins. So as part of a vegetarian or vegan diet, plant-based failure than men not so advised. Another study found fish omega-3s provide better protection from heart disease oil supplements increased life-threatening abnormal heart and many other degenerative conditions. This benefits the rhythms in patients with implanted defibrillators. environment as well; plant-based sources of omega-3s are sustainable, fish are not. A review of studies on fish oils and heart health (which included over half a million heart disease patients), showed Safer, healthier and sustainable sources of omega-3s include no clear benefit of omega-3 fats on heart health. One flaxseeds (linseeds), rapeseeds, soya, walnuts and oils made possible explanation the authors suggest for this is the from them. Some species of algae (and supplements made harmful effects of toxins found in oily fish. Many people from them) can provide the longer chain omega-3s found are unaware that all the world’s oceans and rivers are in oily fish without exposing you to harmful pollutants. By contaminated with toxic pollutants such as polychlorinated avoiding fish you can protect your health and help stop the biphenyls (PCBs), dioxins and mercury. These toxins destruction of the oceans caused by over-fishing. accumulate, especially in fatty fish, as you move up the food chain and may completely cancel out any beneficial effects the omega-3s offer. So you are better off getting The research clearly shows that fish oils are not the wonder your omega-3s from healthy plant-based sources such as food the industry would have you believe. They don’t flaxseed oil, hempseed oil and walnuts. These foods are not guarantee good heart health and turn all kids into geniuses. laced with toxic pollutants. They are not the answer to arthritis and other inflammatory conditions (which vegetarians suffer much less from). We This is why the Government has issued warnings to young must stop looking for a ‘quick fix’ and focus on the bigger people, pregnant and breast-feeding women, and those picture… improving our diets by cutting out the foods laden who may become pregnant one day, to limit how much oily with animal fats, sugar, salt and cholesterol and eating more fish they eat. Some governments warn that pregnant and fruit, vegetables, pulses, wholegrains, nuts and seeds. breastfeeding women and children under 16 should not eat larger, older fish such as shark, marlin or swordfish because This fully-referenced scientific report examines the science of the high levels of mercury present. Others have voiced behind the health claims and reveals the research the fish concerns about the levels of dioxins in herring, salmon and industry would rather ignore. It describes why omega-3 mackerel, but most people know little about these risks. fatty acids are important and explains why plant-based These pollutants can harm children and adults as well as oils are better for human health and the environment. It unborn babies and infants. also describes what toxic substances are found in fish and reveals how harmful they can be. It explains why public More recently the Government has extended its warnings health policies promoting oily fish are misplaced and on dioxins and PCBs to include some non-oily fish including: undermine more effective and sustainable strategies. It will sea bream, turbot, halibut, dog fish or huss, and sea bass. leave you in no doubt – fish is not a health food.
5 An introduction to fat The links between the carbon atoms are called bonds and can be single or double. Saturated fatty acids have Why do we need fat? no double bonds and are fully ‘saturated’ with hydrogen Most people regard all dietary fat as ‘bad’ or unhealthy atoms. Monounsaturated fats have one double bond and but the body actually needs a moderate amount of fat polyunsaturated fats have more than one. The way different (or fatty acids) to function properly. Besides being an fatty acids behave in the body is largely determined by the energy source, fatty acids play a crucial structural role in number and location of these double bonds. all cell membranes; they help hold our cells together. They also help our bodies transport, break down and excrete Saturated fat cholesterol. They are used to make important hormone- As stated, saturated fats have the maximum number of like compounds called eicosanoids which regulate many hydrogen atoms attached to the carbon atoms. This makes processes in the body including inflammation and blood the molecule less flexible. So these fats tend to be solid at clotting. Fatty acids help maintain healthy hair and skin, room temperature, such as lard and butter. they protect vital organs and keep the body insulated. They are also needed to transport the fat-soluble vitamins A, D, E Unsaturated fat and K, from food into the body. In summary, without some Unsaturated (monounsaturated and polyunsaturated) fats fats in the diet, we cannot function. tend to be liquid at room temperature, such as olive and sunflower oil. It is their flexible nature that makes these fats The chemical structure of fat so biologically useful. Figure 1 shows how fatty acids are made up of chains of Figure 2. Cis and trans fatty acids configuration carbon atoms (the carbon backbone) that have hydrogen atoms attached to them. They are referred to as saturated, monounsaturated or polyunsaturated depending on the number of hydrogen atoms attached to the carbon backbone. cis Figure 1. Saturated, monounsaturated and Saturated trans polyunsaturated fatty acids Cis and trans fats The usual shape of naturally occurring unsaturated fats is referred to as ‘cis’ (Latin for ‘on the same side’), as the hydrogen atoms face the same direction (see Figure 2). When the hydrogen atoms are oriented in opposing Saturated fatty acid molecule directions, the molecule is called a ‘trans’ fatty acid (trans means ‘across’ in Latin). Most trans fats are made industrially by adding hydrogen to unsaturated plant oils, in a process called hydrogenation. This process reshapes the double bonds, twisting them so that the hydrogen atoms end up on different sides of the chain. While trans fats are made of exactly the same building Monounsaturated fatty acid molecule blocks as non-trans fats, their different arrangement affects the physical properties of the fat. They are harder, have a higher melting point, and crucially, a longer shelf-life than their cis-shaped equivalents. There is increasing evidence that trans fats are harmful to health. While both saturated and trans fats increase levels of LDL cholesterol (so-called ‘bad’ cholesterol), trans fats also Polyunsaturated fatty acid molecule lower levels of HDL cholesterol (‘good’ cholesterol), thus increasing the risk of heart disease. Indeed, some evidence suggests that trans fats may be even more harmful to health than saturated fats. This position is supported by a scientific Single bond Hydrogen review published in the New England Journal of Medicine Double bond Carbon in 2006 which states that the consumption of trans fatty acids results in considerable potential harm but no apparent benefit (Mozaffarian et al., 2006). Many health authorities worldwide agree and recommend that consumption of trans fat be reduced or avoided altogether.
6 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils God fat, bad fat We need a moderate amount of so-called ‘good’ fats in the Table 1: Nutritional content of selected oily fish and vegetarian alternatives diet. However, not all fats are created equal. As stated, some 100 grams of: Protein Fat Saturated fat Cholesterol Fibre Energy are beneficial, while others can (grams) (grams) (grams) (milligrams) (grams) (kcal) be harmful. For example, as 60 per cent of the brain is made of fat, it is very important that it is Grilled salmon 24.2 13.1 2.5 60 0 215 provided with enough ‘bendy’ polyunsaturated fatty acids to Smoked mackerel 18.9 30.9 6.3 105 0 354 stay supple and elastic in order to be able to respond to different Tinned sardines 23.3 14.1 2.9 65 0 220 stimuli such as hormones. If the cell membranes in the brain (and other parts of the body) are Smoked tofu 10.9 7.1 1.5 0 0.5 112 rigid they cannot react so well (Saldeen and Saldeen, 2006). This Red lentils, boiled 7.6 0.4 Trace amounts 0 1.9 100 means that less flexible (more saturated) fats may take their Kidney beans, boiled 8.4 0.5 0.1 0 6.7 103 place and normal functioning can be impaired. Tinned chick peas 10.3 2.5 0.2 0 4.3 119 Coldwater fish (salmon, mackerel, sardines and herring) need a high Vegetarian style fish 13.3 15.2 1.9 0 1.0 279 level of flexible polyunsaturated fingers (Redwoods) fats in their cell membranes to enable them to see and swim in cold, dark, watery environments. Sources: Food Standards Agency, Sainsbury’s, Redwoods and Cauldron Foods Just imagine replacing these flexible fats with those from a cold pat of butter (saturated fat), it would not work! Fish 280 milligrams per 100 grams; nearly four times as much obtain their polyunsaturated fats from plankton, algae as is found in a rump steak (FSA, 2002). Whichever way it is and other fish. These fats are also found in eggs and dairy dressed up, fish is not a low-fat food and the high levels of foods (which also contain unhealthy saturated fats) and are cholesterol and saturated fat found in some fish foods make plentiful in plant foods such as nuts and seeds and their them an unhealthy option. oils, avocados and soya foods. Green leafy vegetables contain them too, but not much as they are a very low-fat It could be argued that diets containing oily fish are food. Although olive oil contains some saturated fat, it is associated with a lower risk of heart disease and stroke mainly made up of monounsaturated fat, which is a good compared to diets rich in red meat and dairy foods. substitute for butter, lard or omega-6 fats, such as sunflower However, a vegetarian or vegan diet is the healthiest option. oil, in cooking. Dr Neal Barnard, president and founder of the Physicians Committee for Responsible Medicine in Washington DC, While unsaturated fats are an important part of our diets, says that fish are not low enough in fat or cholesterol to we have absolutely no dietary requirement at all for achieve what vegetarian diets can in terms of promoting saturated fat. Found widely in meat, dairy, eggs, poultry, health. He points out that although the fat content of fish processed foods and fish, this unhealthy type of fat varies widely, all fish contain cholesterol and more fat than contributes to the risk of heart disease and stroke by raising is generally found in the foods that make up a well- blood cholesterol levels. balanced plant-based diet (wholegrains, pulses, fruit and vegetables) most of which contain well under 10 per cent Despite its reputation for containing unsaturated ‘healthy’ fat (Barnard, 2003). fats, much of the fat found in oily fish is saturated (see Table 1). For example, nearly 80 per cent of the calories in smoked In summary, plant-based diets inevitably contain mackerel come from fat and over half of the calories in considerably lower amounts of saturated fat (and either grilled salmon come from fat. Around one-fifth of the total less or no cholesterol) compared to typical Western fat in both these types of fish is saturated (FSA, 2002). diets. Research shows that vegetarians consume a third less saturated fat and only half as much cholesterol as Fish and shellfish are also significant sources of cholesterol; omnivores. Vegans consume even less: half the amount of some species containing nearly as much as steak. The saturated fat eaten by omnivores and no cholesterol (Davis amount of cholesterol in prawns is estimated to be around and Kris-Etherton, 2003). This contributes significantly to
7 their lower risk of heart disease, stroke and many other docosahexaenoic acid (DHA). LA is an omega-6 fatty acid diseases. (as the first double bond occurs at the sixth carbon atom). Similarly, our tissues can convert it into other longer chain Getting to know the EFAs omega-6 fatty acids, such as gamma-linolenic acid (GLA) In the late 1920s the scientists George and Mildred Burr first and arachidonic acid (AA). introduced the idea that specific components of fat could be necessary for normal growth and development (Burr and Although AA, GLA, DHA and EPA are physiologically Burr, 1929). Since then two specific polyunsaturated fatty important, they are not referred to as ‘essential’ as they can acids have been classified as ‘essential’ as they cannot be be produced in the body from LA and ALA. The essentiality manufactured within the body; they must be provided in of ALA and LA in humans is best explained by our inability the diet. Hence, they are called ‘essential fatty acids’ (EFAs). to introduce double bonds in positions before carbon The two EFAs required for good health are the omega-3 nine (Uauy et al., 2003). In other words, they are classed as fatty acid alpha linolenic acid (ALA) and the omega-6 fatty essential as we can’t make these fats in our bodies. acid linoleic acid (LA). EFAs are important for the normal functioning of all tissues of the body. Figure 3: The fatty acid family They are necessary for the formation of healthy cell membranes, the proper Fats and fatty acids development and functioning of the brain and nervous system and for the production of eicosanoids, important Saturated fats regulators of vital body functions such Unsaturated fats Animal fats, butter, lard as blood pressure, blood-clotting, and immune and inflammatory responses. Polyunsaturated fats Monounsaturated fats How much fat? The UK Dietary Reference Values for the total amount of fat and different Omega-3 fatty acids Omega-6 fatty acids Omega-9 fatty acids fatty acids in the diet were published Alpha linolenic acid (ALA) Linoleic acid (LA) Oleic acid in 1991 (Department of Health, 1991). Eicosapentaenoic acid (EPA) Gamma linolenic acid (GLA) Additional recommendations were Docosahexaenoic acid (DHA) Arachidonic acid (AA) made for omega-6 and omega-3s by the Committee on Medical Aspects of Food (COMA) in 1994 in a review on the ALA is described as an omega-3 fatty acid because the nutritional aspects of CVD (COMA, 1994). first double bond occurs at the third carbon atom along the carbon backbone of the molecule. As shown in Figure Taken together, current UK recommendations are that total 3, ALA can be converted in the body into the longer-chain fat intake should contribute no more than 33 per cent of omega-3 fatty acids eicosapentaenoic acid (EPA) and daily total energy intake and that saturated fats should contribute an average of no more than 11 per cent of food energy, monounsaturated fats an average Table 2: WHO recommendations for daily fat intake of 13 per cent, polyunsaturated fats 6.5 per cent and trans fats no Type of fat Percentage Grams required for women Grams required for men more than two per cent. COMA of total energy (19-50) consuming (19-50) consuming recommended that among the 1,940 calories/day (kcal) 2,550 calories/day (kcal) general population there should be no further increase in average intakes of omega-6 fats but that Total fat 15-30 32.3-64.7 42.5-85.0 intakes of long-chain omega-3 (EPA and DHA) fats should Saturated fat Less than 10 Less than 21.6 Less than 28.3 increase from about 0.1 grams to 0.2 grams per day (COMA, 1994). Polyunsaturated fats 6-10 13.0-21.6 13.3-28.3 These recommendations are Omega-6 5-8 10.8-17.2 14.2-22.7 similar to those given by the World Health Organisation Omega-3 1-2 2.2-4.3 2.8-5.7 (WHO) and Food and Agriculture Organisation (FAO). These are summarised along with the Source: WHO/FAO, 2003.
8 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils actual amounts of each type of fat required to meet these recommendations in Table 2. Table 3. Oily and non-oily (white) fish In summary, total fat intake should contribute between 15-30 per cent of total energy intake with less than 10 per Oily Fish Non-oily fish cent from saturated fat. Those obtaining more than 10 per cent of their dietary energy from omega-6 fats should not increase their intake of this fat. Most people need to Salmon Cod increase their intake of omega-3s to provide two per cent Trout Haddock of dietary energy. Less than one per cent of calories (but Mackerel Plaice preferably none), should come from trans fats. Herring Coley Sardines Whiting Pilchards Lemon sole Oily fish Kipper Skate Eel Halibut Oily fish have fats throughout their whole body rather than Whitebait Rock salmon/Dogfish only in the liver like non-oily (white) fish. Oily fish fillets may Tuna (fresh only) Ayr contain up to 30 per cent fat, although this figure varies both Anchovies Catfish within and between species. See Table 3 for a list of oily and Swordfish Dover sole non-oily fish. Bloater Flounder How much oily fish? Cacha Flying fish In 2004, in response to a specially commissioned report Carp Hake on the benefits and risks of oily fish consumption, the Hilsa Hoki Food Standards Agency (FSA) issued guidelines on oily Jack fish John Dory fish intake. Table 4 shows the recommended weekly limits. Katla Kalabasu They suggest a limit on the maximum number of portions Orange roughy Ling of oily fish different groups can safely consume each week Pangas Monkfish (a portion is about 140 grams). However, the FSA says that health benefits are greater than the risks as long as you Sprats Parrot fish don’t eat more than the recommended maximums. Hardly Pollack reassuring! Pomfret Red and grey mullet EFA deficiency Red fish For EFA deficiency to develop, dietary intake must be Red snapper extremely low as even small amounts of EFAs can prevent Rohu deficiency. The 2003 National Diet and Nutrition Survey showed that the average daily total fat intakes were close Sea bass to UK recommendations (FSA, 2003). In fact, most adult Sea bream Western diets provide 8-15 grams of EFAs per day and Shark healthy people have a body reserve of 500-1000 grams in Tilapia adipose tissue (Department of Health, 1991). EFA deficiency Turbot in adults is only seen when they make up less than 1-2 per Tinned tuna cent of total dietary energy (Department of Health, 1991). Where EFA deficiency does occur, it is most often seen in Marlin infants fed very poor diets. Table 4: Food Standards Agency recommendations for the Typical symptoms of EFA deficiency include excessive thirst, maximum number of portions of oily fish we should be eating frequent urination, dry or rough skin, dry hair, dandruff, each week (a portion is about 140g) brittle nails, headaches, stomach ache, diarrhoea and constipation (Stevens et al., 1995). Low omega-3 fatty acid Two portions of oily fish Four portions of oily fish status is also associated with behavioural problems such as hyperactivity-impulsivity, anxiety, temper tantrums, sleep Girls and women who might Other women problems and learning difficulties in some children (Stevens have a baby one day et al., 1996). More specifically, low levels of DHA have been associated with several neurological and behavioural Women who are pregnant or breastfeeding Men and boys disorders such as depression, schizophrenia, Alzheimer’s disease and attention deficit hyperactivity disorder (ADHD) (Davis and Kris-Etherton, 2003). Source: FSA, 2009.
9 fatty acids consumed (Lands, 1992). This is because omega-6 Table 5: Plant sources of EFAs fats compete with omega-3s for use within the body. So excessive 100 grams of: Omega-3 ALA (grams) Omega-6 grams LA (grams) intakes of omega-6 fats can cancel out the positive effects of omega-3s and lead to health Oils problems. Flaxseed (linseed) oil 53.30 12.70 Hempseed oil* 20.00 60.00 Recent changes in the diet have Walnut oil 10.40 52.90 Rapeseed (canola) oil 9.13 18.64 led to a massive rise in our intake Wheatgerm oil 6.90 54.80 of omega-6 fats from plant-based Soya oil 6.79 50.42 oils (such as sunflower oil) and Corn oil 1.16 53.23 most processed foods. This has Sunflower oil 0.00 65.70 increased the ratio of omega-6 to Nuts and seeds omega-3 fats in our diets. Flaxseeds (linseeds) ground, 2 tbsp 22.81 5.90 Walnuts 9.08 38.09 Typical Western diets may Hempseeds* 7.50 22.50 provide ratios of up to 30:1, Vegetables, Fruits and Pulses dramatically skewed toward Soya beans, cooked 0.60 4.47 omega-6 fats. The health Tofu, firm 0.58 4.34 consequences of this could be Broccoli (cooked) 0.11 0.05 far-reaching. Dr. Hibbeln, lead Soya milk 0.08 0.59 clinical investigator on nutrition Strawberries 0.07 0.09 in psychiatry at the National Peas (frozen and cooked) 0.02 0.08 Institutes of Health in Bethesda, Maryland suggests that these major changes in the essential Source: USDA National Nutrient Database for Standard Reference, 2008. * Adapted from Leizer et al., 2000, fatty acid composition of the Journal of Nutraceuticals, Functional and Medical Foods. 2 (4) 35-53. food supply may be linked to a range of psychiatric disorders and may even contribute towards These findings are consistent with evidence that omega-3 fatty an increased risk of homicide, suicide and social instability acids are important for brain function and that low omega-3 (Hibbeln, 2007). intake may have negative effects on behaviour, learning and mood. It is important then to make sure that there are adequate The WHO/FAO joint recommendation is a ratio of LA to ALA levels of these important nutrients by supplying sufficient of 5:1-10:1 (WHO/FAO, 1994). Other recommended ratios vary ‘parent’ fatty acids for conversion. Most people can obtain all but a cautious approach would be to aim for a ratio between the EFAs they require from a well-balanced plant-based diet 2:1 and 4:1 making sure not to exceed 6:1 (Davis and Kris- including flaxseed oil, nuts and seeds as well as plenty of green Etherton, 2003). This ratio can be achieved by reducing the leafy vegetables. In most cases, dietary replenishment of EFAs use of sunflower, safflower and corn oils and increasing the will usually reverse any deficiency. use of ALA-containing oils such as flaxseed, rapeseed and soya bean oils. Of course, optimising omega-3 conversion Table 5 shows which plant-based foods can be used to boost rates can help improve your omega-6:omega-3 ratio too. your intake of omega-3 fats. Note that the fats and oils are easily damaged by light or heat so are best kept refrigerated. Optimising conversion Furthermore, these oils should not be used in cooking; use The body converts ALA into the longer chain omega-3s them on salads, in dressings and dips. (EPA and DHA), otherwise found in fish and some species of algae. However, we are repeatedly told (particularly by fish People with diarrhoea, irritable bowel syndrome, diverticulitis oil supplement companies) that conversion rates are low and or inflammatory bowel disease (Crohn’s disease or ulcerative inefficient. The claim that we cannot convert enough ALA to colitis) should use caution if taking flaxseed (but not flaxseed EPA and DHA is simply not true, but does serve to protect oil) due to its possible laxative effects. If you have a medical the fish oil market. The better health statistics for vegetarians condition, or are taking other drugs or supplements you and vegans – who don’t eat fish – provides proof that they should consult a doctor or nutritional therapist before don’t go short. changing your diet. Several studies have measured the rate at which we convert Balancing the fat ALA to EPA and DHA. A conservative estimate is that about Research suggests that the ratio of omega-6 to omega-3 5-10 per cent of ALA is converted to EPA, and 2-5 per cent fatty may be more important than the amounts of individual to DHA (Davis and Kris-Etherton, 2003). However, as the
10 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils body’s fat deposits usually contain ALA, even a very low and DHA and depletes tissues of these long chain omega-3 conversion rate of just 2.7 per cent, would allow an average fatty acids (Davis and Kris-Etherton, 2003). person to make the same amount of EPA as would be found in 18 large (1,000mg) capsules of the omega-3 richest fish oil Consuming excessive amounts of omega-6 fatty acids (Erasmus, 1993). Even a person with no omega-3 fats in their (associated with some vegetable oils, particularly safflower, body, (perhaps after a long-term dietary shortfall) who takes sunflower and corn oils) can have a detrimental effect on two tablespoons of flaxseed oil a day, can produce more conversion rates too (Uauy and Castillo, 2003). Indeed, a EPA than contained in two large fish oil capsules. high omega-6 intake may reduce omega-3 conversion by as much as 40 per cent (Davis and Kris-Etherton, 2003). Other studies show much higher levels of conversion. There is no need to avoid or cut down on omega-6-rich Research from the Institute of Human Nutrition at the wholefoods (sunflower seeds, pumpkin seeds, sesame University of Southampton found ALA conversion rates in seeds, wheat germ and soya foods) as they contribute much young women of 21 and nine per cent for EPA and DHA less to overall omega-6 intake and contain an abundance of respectively (Burdge and Wooton, 2003). other healthy nutrients. Furthermore, a recent study from the University of Davis and Kris-Etherton recommend that the primary Cambridge revealed that vegetarians convert more ALA fat in the diet should come from foods and oils rich in to EPA and DHA than fish-eaters (Welch et al., 2008). In monounsaturated fat, as when monounsaturated fats this study, the ratio of circulating EPA and DHA to dietary predominate, saturated fats, trans fats and omega-6 intake of ALA was used as an indicator of conversion rate; fats are kept in check (Davis and Kris-Etherington, 2003). the higher the ratio, the greater the conversion rate. Results Monounsaturated fats are found in nuts, peanuts, olives and showed the ratio was 22 per cent higher in vegetarians than olive oil, avocados and rapeseed oil. As stated, wholefoods fish-eaters, indicating a higher conversion rate. This may are superior source of fats as they contribute many other explain why fish-eaters and non fish-eaters have a smaller nutrients to the diet. than expected difference in circulating omega-3 levels. Lastly, it is important to optimise the intake of ALA for Taken together, the research indicates that we can convert conversion into EPA and DHA. As stated above, ALA should as much or as little as we need, providing we have enough provide 1-2 per cent of total energy intake in the diet. Good starting material (ALA). sources include ground flaxseeds and their oil, hempseed, rapeseed, walnuts, soya beans and products made from In addition to this, we are capable of ‘retroconversion’, them, green leafy vegetables and some species of algae which means we can make EPA from DHA. Research from (which contain DHA). Table 6 shows the amount of omega- the Department of Nutritional Sciences at Pennsylvania 3-rich food you can take to achieve the recommended daily State University states that up to 10-11 per cent of DHA is intake (along with a well-balanced plant-based diet). retroconverted to EPA. The authors of this study conclude that if sufficient ALA and DHA are consumed, total EPA If more people knew that they could produce sufficient production would be expected to be adequate (Davis and amounts of EPA and DHA from ALA they might be less Kris-Etherton, 2003). inclined to turn to potentially decaying and contaminated So if you take an algal supplement that contains DHA you can boost both DHA and EPA levels without exposing yourself to toxic pollutants found in fish oils. Furthermore, Table 6: suggested daily intake of foods rich in omega 3 the EPA we make in our bodies has the advantage of being fresher and more stable than that found in fish oils. Source One of the following A range of dietary factors can affect efficiency of conversion too. Poorly designed diets are thought to reduce the rate of Flaxseed (linseed) oil 1-2 tsp conversion as both energy and protein are needed to drive the enzymes that convert EFAs. In addition, a wide range Ground flaxseed (linseed) 2 tbsp of nutrients are required to optimise conversion including biotin, calcium, copper, magnesium, niacin (vitamin B3), pyridoxine (vitamin B6), vitamin C and zinc (McKevith, 2005; Rapeseed oil 2 tbsp Siguel and Lerman, 1994; Horrobin, 1992). A well-balanced plant-based diet will provide all these nutrients and more. Hempseed oil 1 tbsp Excessive intakes of trans fatty acids can limit conversion rates. These unhealthy fats, found in hydrogenated fat in Hempseed 3-5 tbsp margarine and products made with it (such as biscuits and pastries), are also found in meat and dairy products. Alcohol Walnuts 8 halves (28 grams) inhibits activity of the enzymes that convert ALA into EPA
11 fish oils. The research indicates that the only thing Reinfarcation Trial (DART) (Burr et al., 1989). This study vegetarians and vegans miss out on by avoiding fish is the looked at the effects of dietary intervention in the toxic pollutants that contaminate them. secondary prevention of heart attacks in patients who had previously recovered from one. In this study 2,033 men who Omega-3s from algae – cut out the middleman had recovered from a heart attack were allocated to receive Whilst omega-3 is present in fish oil, fish do not produce or not receive advice to eat around 300 grams of oily fish omega-3 in their bodies. Fish obtain their omega-3 from per week, or take fish oil supplements giving an equivalent their diet of algae. People who are concerned about intake amount of omega-3 fats. of DHA can use algal supplements as a source of this long chain omega-3 too. There are even brands available online Results showed that the fish group had a 29 per cent that can provide both DHA and EPA. reduction in death during the two year recovery period following a heart attack. So it was concluded that fish oil Algae used for omega-3 supplements is usually grown may reduce CVD mortality; the effect being greatest during in controlled conditions away from the sea, so it doesn’t the period of recovery following a heart attack. interfere with the marine ecosystem and doesn’t impact on fish stocks nor their natural food source. So, in addition Burr suggested that omega-3 fats may help normalise to the numerous health benefits of this vegan-friendly heartbeat rhythms by exerting what is called a beneficial source of long chain omega-3s, it is a more environmentally anti-arrhythmic effect. In other words, omega-3s may help friendly choice. your heart beat more regularly and calm irregular activity (arrhythmia). Others agree that the most likely mechanism By switching from fish to a plant-based source of omega-3 by which EPA and DHA reduce the recurrence of heart you’ll be doing yourself a favour and the environment too, disease is by stabilising arrhythmias (Marchiolo et al., whilst getting the safest, toxin-free omega-3 fats. 2002). Research suggests that the anti-arrhythmic effect of omega-3 fats is partly due to their ability to reduce the electrical excitability of cells. Oily fish, EFAs and health As stated, fish oils (or components of them) may also offer benefit by reducing blood-clotting. Platelet cells Heart health found in the blood ensure that blood becomes sticky Why are oily fish promoted as essential for good health? (platelet aggregation or blood-clotting). This is important The answer lies, partly, in the role EFAs may have in for stopping bleeding, for instance, if you are wounded. lowering the risk of heart disease and stroke. However, too much clotting can cause the cells to clump together and stick to the walls of blood vessels. This can Oily fish first got the nutritional thumbs up when it was lead to heart disease and stroke. EPA appears to reduce observed that populations such as the Japanese and Inuit the tendency of blood platelets to clump together. (Eskimo) people, with their fish-rich diets, have much lower Consequently, it may prevent the formation of blood rates of CVD. Further investigation suggested that the EPA clots and the narrowing of coronary arteries, which can and DHA fatty acids found in fish can help reduce blood- lead to a heart attack. However, extensive reduction in clotting, lower blood pressure and cholesterol levels and platelet aggregation can lead to prolonged bleeding times lower triglyceride (fat) levels in the body. All these effects following injury. It is important that blood is neither too can help lower the risk of CVD. However, the promotion thick nor too thin. of oily fish ignores the fact that EPA and DHA can also be formed within the body from plant sources of ALA. Those taking blood-thinning medication (such as daily Not to mention the toxic pollutants found in fish and the aspirin or warfarin), should speak to their GP before eating environmental catastrophe of industrial fishing. lots of food that has added omega-3 or before taking fish oil supplements, as this can also reduce blood-clotting. Numerous studies have looked at the benefits of eating polyunsaturated fatty acids (particularly the omega-3s: ALA, Interestingly, although there were less fatal heart attacks EPA and/or DHA) to reduce the risk of heart disease. Three among the DART fish group, the total number of attacks major studies are frequently referred to: the DART, GISSI was not reduced. So although eating oily fish reduced and LYON studies. The DART and GISSI trials demonstrated the risk of dying after a heart attack, it did not prevent a how fish oils could reduce mortality in people with CVD. secondary heart attack. Whereas a large body of evidence However, there is now a large body of evidence showing shows that plant-based diets can be used to both prevent how plant-based ALA can do the same without exposure to and even reverse heart disease (see the VVF guide Have a harmful toxins found in oily fish. The third well-known study, Heart for further information). the LYON study, clearly demonstrated this. GISSI – using fish oil supplements to prevent DART – using dietary fish to prevent secondary secondary heart disease heart disease The GISSI-Prevenzione trial similarly looked at the effect One of the best-known early studies was the Diet and of EPA and DHA on 11,324 patients (primarily men) who
12 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils had recently survived a heart attack. Half the participants identical. So the dietary advice given to former DART received a daily supplement (1 gram per day) of omega-3 participants, over a decade previously, offered no long- fish oil capsules, while the other half did not (GISSI, 1999). term protective effect. So while fish oil may offer short-term protection to people who have suffered a heart attack, this After three-and-a-half years, results showed a 20 per cent protection does not appear to stand the test of time. reduction in the overall death rate among the fish oil group. However, like the DART trial, the rate of non-fatal A further study looked at whether dietary advice (to eat oily heart attacks was unchanged. It should also be noted that fish or fish oil supplements) could reduce the death rate the large amount of omega-3 fats given (1 gram) is the among men with angina (Burr et al, 2003). Another surprising equivalent of consuming a very large amount (around 100 result was found: advice to consume fish and the intake of grams) of oily fish per day. This exceeds the ‘safe’ amount fish oil capsules was associated with an increase in mortality the UK government recommends (FSA, 2009). of 20 per cent and 45 per cent respectively! Furthermore, this increase was even more prominent for sudden death. More recently, a Finnish study looking at the relationship Such results should make health organisations and the between omega-3 levels and the five-year risk of heart Government sit up and rethink their position on fish and fish attack and death in patients with heart disease found that oil in the primary and secondary prevention of heart disease. relatively high blood levels of omega-3 fats were associated with a lower risk of death (Erkkilä et al., 2003). However, like More recently, in 2006, a major review published in the British the previous trials, omega-3s did not prevent the recurrence Medical Journal drew the evidence together by reviewing all of a heart attack. This finding fits well with those from the relevant studies published over the previous four years earlier studies showing that fish consumption and omega-3s (Hooper et al., 2006). It looked at 89 studies on omega-3 fats may be associated with decreased death rates but do not and health and concluded that long chain and shorter chain necessarily prevent a secondary heart attack in high-risk omega-3 fats do not have a clear effect on total mortality, subjects. Conversely, there is a huge body of evidence (see combined cardiovascular events or cancer. below) showing how vegetarian or vegan diets can actually reverse heart disease in patients and so reduce both death The review noted that the 2003 study by Burr contradicts the rates and secondary heart attacks. other large studies by not suggesting a benefit of omega- 3s in patients with angina. One possible explanation the No benefit from fish for low-risk heart researchers suggest for this is that as this trial had the longest disease populations follow-up period of all the studies reviewed it could be that While the DART and GISSI trials suggested that fish oils may the negative effects of oily fish and fish oil supplements reduce death rates in people who have already had a heart were due to the cumulative harmful effects of mercury. In attack, the same cannot be said for the wider population. other words, the pollutants in fish and fish oil supplements A major review of studies examining the relationship taken over time may cancel out the beneficial effects of the between fish intake and heart disease found that fish omega-3 fats they contain. consumption is not associated with a reduced risk in low- risk populations (people with no history of heart problems) Another study found fish oil supplements increased life- (Marckmann and Gronbaek, 1999). This review concluded threatening abnormal heart rhythms in patients with that healthy people (at low-risk of heart disease) do not gain any additional protection for the heart from eating fish. implanted defibrillators (Raitt et al., 2005). This study actually The authors question whether the apparent protection in found that fish oil supplementation did not reduce the risk of high-risk individuals is attributable to eating fish or whether abnormal or irregular heart rhythm and may even be pro- the link might be explained by other dietary or non-dietary arrhythmic in some patients. confounding factors. LYON – using plant-derived ALA to prevent In a later editorial, one of the review authors reaffirmed secondary heart disease that while an average daily intake of 50 grams of fish may The Lyon Diet Heart Study investigated whether a lower heart disease death rate, the apparent protection Mediterranean-type diet could reduce secondary heart is limited to high-risk populations (Marckmann, 2003). disease (a second heart attack) compared to a prudent Marckmann observes that both the DART and GISSI trials Western-type diet (de Lorgeril et al., 1999). were well-designed and performed and the results were convincing. However, he says that their conclusion, that heart In this study, 423 patients with a history of heart attack were disease patients should be prescribed oily fish or fish oil randomly assigned either a Mediterranean diet or a prudent supplements, has been seriously challenged by more recent Western diet (as recommended by the American Heart research. Association). The Mediterranean diet was largely plant-based containing more bread, pulses (peas, beans and lentils), No long-term protection against heart disease vegetables (both root and green vegetables) and fruit. Butter A long-term follow-up to the DART study (Ness et al., 2002), and cream were replaced with healthier fats including olive showed that the death rate in the two groups (fish and oil and rapeseed oil margarine. The diet did contain fish, but no fish) after an average follow-up of 15 years was almost less red meat, and overall it was lower in animal fat.
13 The Mediterranean diet was significantly lower in cholesterol Evidence suggests that LDL can also harm the walls of and higher in a number of beneficial substances such as ALA. the arteries when it is damaged or oxidised (Galassetti Earlier work with this group revealed a 70 per cent increase and Pontello, 2006). So what has this to with the diet and in circulating levels of ALA and a 40 per cent rise in EPA (de what can be done about it? Well, quite a lot. For example, Lorgeril et al., 1994). Although fish intake was encouraged, one study showed how eating two eggs a day for three the experimental group ate only seven grams a day more fish weeks not only raised LDL levels by about 10 per cent than the control group, leading the researchers to conclude but increased oxidised LDL by 34 per cent (Levy et al., that the favourable EPA level seen in the test group was due 1996). The authors concluded that egg consumption, in to plant-ALA intake rather than the fish in the diet. addition to raising cholesterol, increased how readily LDL could be oxidised. This, in turn, enhanced the progression Results showed a striking drop in death rates (due to a of atherosclerosis (the build up of fatty deposits in the reduction in heart disease) of close to 70 per cent. Compared arteries). It was concluded that this may contribute to the with the DART trial, the protective effect was associated high levels of heart disease seen in populations with high with ALA instead of EPA. Another important difference cholesterol intakes. was that the protection ALA offered extended to non-fatal heart attacks. The authors of this study suggested that The precise mechanism underlying how eggs increase LDL moderate amounts of omega-3 fatty acids (such as in the oxidation is unclear, although their relatively high omega-6 Mediterranean diet), may work in multiple ways to reduce the intake has been blamed (Shapira and Pinchasov, 2008). risk of heart attacks and sudden death. Conversely, a healthier diet, such as the Mediterranean diet (rich in antioxidants and flavanoids), appears to reduce how Just to be clear, the only fatty acid associated with the readily LDL is oxidised (Lapointe et al., 2006). Interestingly reduction in heart attacks was ALA. The authors did not find though, antioxidant supplements and fish oil supplements have not been clearly demonstrated to prevent LDL any correlation between the longer-chain omega-3 fatty oxidation. acids (EPA and DHA) and a reduction in cardiac events. The Lyon Diet Heart Study demonstrated that plant-derived ALA Research shows that LDL in vegetarians is less susceptible is extremely effective in reducing the risks of secondary to oxidative damage (Lu et al., 2000). This may be due to heart disease. It demonstrated that plant ALA was superior the low-fat, high-antioxidant (beta-carotene and vitamins to fish-derived EPA and DHA in reducing the risk of a second C and E) and/or soya food content of a well-balanced heart attack. This study also confirmed that ALA can confer plant-based diet. This could be one of the reasons why the long-term protection to heart health. Mediterranean diet is associated with a lower incidence of heart disease (Lapointe et al., 2006). These and other Three years later, in an article published in the journal studies provide strong evidence that plant-based omega-3s Circulation, Dr J. David Spence of the Stroke Prevention can protect heart health and that contrary to popular belief, and Atherosclerosis Research Centre at Robarts Research oily fish are not the only (nor indeed the best) source of Institute in London, Canada, asked why the Lyon study was these valuable nutrients. so neglected (Spence, 2002). Spence believes this study should have set the benchmark for dietary recommendations. Spence states that it is no longer reasonable for patients He stressed how Mediterranean diets have been shown to with heart disease to be prescribed diets containing improve endothelial function (how the internal lining of the a daily intake of animal flesh (Spence, 2002). Dietary blood vessels work). Spence also attributed the protective recommendations, he suggests, should be based on diets role of this type of diet to the higher levels of antioxidants similar to that used in the Lyon study. they contain. A large body of evidence indicates that antioxidants may be able to reduce atherosclerosis (the Plant omega-3s and heart disease progressive thickening and hardening of arterial walls that Many other studies indicate that plant omega-3s have results from the build up of fatty deposits) (Azen et al., 1996). a protective effect against heart disease. The Health Professionals’ Study looked at 43,757 men over six years Spence also suggested that dietary cholesterol is more (Ascherio et al., 1996). During this time 229 men suffered harmful to health than previously thought. Cholesterol is a a fatal heart attack and 505 a non-fatal heart attack. This fatty substance mainly produced by the liver (in response to study found that a one per cent increase in ALA intake saturated fat intake) but it is also supplied in diets containing lowered the risk of heart attack by 59 per cent. It was animal-based foods (meat and dairy). Plant foods don’t concluded that diets high in ALA from plants are associated contain any cholesterol. It is carried in the bloodstream by with a reduced risk of heart disease. molecules called lipoproteins (a mixture of fat and protein). Low-density lipoprotein (LDL) takes cholesterol from the Similar findings were reported in the Nurses’ Health Study liver to the cells and is often referred to as ‘bad’ cholesterol which looked at over 76,000 women over 10 years (Hu et because when levels are high, it can accumulate on the walls al., 1999). During this time 232 women suffered a fatal heart of the arteries. High-density lipoprotein (HDL) carries excess attack and 597 a non-fatal attack. Those who consumed the cholesterol back to the liver for excretion and is therefore most ALA had a 45 per cent lower risk of fatal heart disease. called ‘good’ cholesterol. The risk was further lowered among women who also took
14 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils vitamin E supplements or who had a lower intake of trans With declining fish stocks, polluted seas and oceans, fatty acids. The authors concluded that higher consumption the role of plant-based omega-3s in heart disease must of foods such as oil-based salad dressings that provide be further examined. The possibility of a simple and polyunsaturated fats, including ALA, may reduce the risk of sustainable plant-based solution can no longer be ignored. fatal heart disease. Veggie diets and heart disease In the 2001 National Heart, Lung and Blood Institute Family Plant-based diets have been shown to prevent and even Heart Study, the diets of 4,584 participants were assessed reverse heart disease. Dr Dean Ornish, Clinical Professor of (Djousse et al., 2001). Results showed that men who Medicine at the University of California in San Francisco, is consumed the most ALA had a 40 per cent lower risk of heart well-known for his Lifestyle Heart Trial in which he treated disease and women who consumed the most had a whopping severe heart disease patients with lifestyle changes alone 50-70 per cent reduction. (Ornish et al., 1990; Ornish et al., 1998). The experimental group ate a low-fat wholegrain plant-based diet containing In 2003, a joint report by WHO/FAO concurred that ALA has a lots of fruits, vegetables and pulses. They also followed protective effect against heart disease (WHO/FAO, 2003). The an exercise programme, practised various forms of stress report states that several prospective studies have found an management but did not receive medication. They were inverse association between the intake of ALA (from flaxseed, monitored against a control group of similar patients who rapeseed and soya bean oils) and risk of fatal heart disease. In received conventional treatments. other words, ALA protects against death from heart disease. After just one year, 82 per cent of patients on this lifestyle It has been suggested that the protective effects of ALA are change regime had regression of their heart disease with a particularly evident among subjects with low intakes. This 91 per cent reduction in chest pain and reduced cholesterol may be in parts of Europe where sunflower oil is used almost levels. Whereas the control group experienced a 165 per exclusively, or in developing countries where palm oil is used cent increase in the frequency of chest pain, cholesterol (both oils lack ALA). was worse and blockages of their arteries became worse. This trial has continued with similar results and continues to In 2008, a study published in Circulation, the Journal of the achieve better results than conventional surgical or medical American Heart Association, investigated the role of ALA in intervention. heart disease in Costa Rica where ALA intake was low but is increasing due to the switch from palm oil to soya bean oil More recent work shows that vegetarians generally have a (Campos et al., 2008). This study found that a 1.79 gram per much lower risk of heart disease than meat-eaters. A major day intake of ALA (supplying 0.65 per cent of total energy) review of the scientific evidence shows that vegetarians decreased the risk of a second heart attack in heart disease have a massive 25 per cent lower risk of dying from heart patients by 57 per cent, compared to a 1.11 gram per day disease! The authors of this study conclude that the intake (supplying 0.42 per cent of total energy). The authors widespread adoption of a vegetarian diet could prevent suggest that the amount of ALA needed to reduce the risk of approximately 40,000 deaths from heart disease in Britain a second heart attack can be obtained from just 2 teaspoons each year (Key et al., 1999). of soya bean or rapeseed oil, 1-2 millilitres of flaxseed oil or just 6-10 halves of walnuts per day. As stated, meat, poultry, fish, eggs and dairy products all contain cholesterol, while a plant-based diet contains little The Cochrane Collaboration is an international not-for-profit, or no cholesterol. It should be no surprise then that a large- independent organisation, dedicated to making up-to-date, scale study investigating cholesterol levels among vegans, accurate information about the effects of healthcare readily vegetarians, fish- and meat-eaters found that the vegans available worldwide. The Collaboration’s systematic reviews had the lowest levels, vegetarians and fish-eaters had of healthcare studies are published quarterly as part of The similar values and the meat-eaters had the highest (Appleby Cochrane Library. Cochrane reviews have become known et al., 1999). internationally as sources of high quality, reliable health information. For vegans it’s a win-win situation. Not only do they avoid harmful substances (saturated animal fat, animal protein In 2004, the Cochrane Collaboration reviewed the current and cholesterol), they also benefit from a wide range of evidence to see whether dietary or supplemental omega-3 healthy nutrients including fibre, vitamins and minerals. fatty acids alter total mortality (death rate) or cardiovascular events (heart attack and stroke) (Hooper et al., 2004). They Inflammatory diseases concluded that there was no overall benefit either on heart It is reported that omega-3 fats can help fight heart attacks, deaths from heart disease or overall mortality. The disease, asthma, type 1 diabetes and multiple sclerosis. authors concluded that there was not enough evidence to say The beneficial effects have also been seen in some cancers, that people should stop taking rich sources of omega-3 fats, inflammatory bowel disease, arthritis, osteoporosis, mental but said that further high quality trials are needed to confirm health, dry eye disease, age-related macular degeneration the previously suggested protective effect of omega-3 fats for and psoriasis (Simopoulos, 2008). Many of theses conditions those at increased cardiovascular risk. involve inflammation.
15 Our bodies use inflammation to protect tissues from This chronic condition is characterised by hot painful infection, injury or disease. The inflammatory process swelling in the joints. It usually starts in the wrists, hands usually promotes healing but, when uncontrolled, it can and feet but can spread to other joints in the body. In some also harm. We now know that the balance of omega-6s diseases inflammation can help towards healing, but in to omega-3s is important for regulating inflammation. rheumatoid arthritis it tends to cause damage. For some As a general rule, omega-6 fats are thought to be pro- people the discomfort, pain and loss of mobility caused by inflammatory, whereas omega-3 fats are considered anti- this condition can have a serious impact on their lives. inflammatory (GLA is the exception as it is an omega-6 fat with anti-inflammatory properties). The dramatic Rheumatoid arthritis affects approximately 350,000 people increase in dietary saturated and omega-6 fats, coupled in the UK and like osteoarthritis, is also more common in to the decrease in omega-3 fats is linked to the increasing women than men. It is most common after the age of 40, but incidence of numerous inflammatory diseases including can affect people of any age (NHS Direct, 2008b). asthma, allergy and atherosclerosis (Chilton et al., 2008). Diet and arthritis There is evidence that changing the diet can help some In the past, arthritis patients were told that dietary changes people with inflammatory conditions; some of these are would not help them. Despite this many arthritis patients discussed below. have found that certain foods can worsen their condition, or improve it. Arthritis Arthritis is a painful condition of the joints and bones. Arthritis Care is the UK’s largest voluntary organisation There are many different forms of this condition. The two working with and for people with arthritis. It suggests that a main types are rheumatoid arthritis and osteoarthritis. diet high in fruit, vegetables, pasta, fish and white meat, and low in fatty foods such as red meat, cream and cheese can Other forms of arthritis include ankylosing spondylitis, help (Arthritis Care, 2008). Most people would benefit from cervical spondylitis, fibromyalgia, lupus, gout, psoriatic eating less saturated fat and sugar and eating more complex arthritis and Reiter’s syndrome (NHS Direct, 2008). carbohydrates, fibre, vitamins and minerals. Evidence shows that at least for some people with arthritis, a healthier diet Osteoarthritis can help considerably. Osteoarthritis is the most common type of arthritis in the UK, with an estimated 8.5 million people affected by the In 2001, the first controlled study examining the long-term condition (NHS Direct, 2008a). This degenerative disease is effect of a vegan, gluten-free diet on rheumatoid arthritis sometimes referred to as ‘wear and tear’ arthritis. Cartilage found that this diet could improve the signs and symptoms is the strong, smooth surface that lines the bones and of this condition (Hafström et al., 2001). The authors of allows joints to move against each other easily without this study suggested that a gluten-free vegan diet may, in friction. In osteoarthritis, cartilage gradually breaks down some people, reduce the immune response that triggers faster than it can be repaired. Eventually the surface of the rheumatoid arthritis. Another study tested a low-fat, vegan bones begin to rub together causing them to degenerate. diet in patients with moderate-to-severe rheumatoid arthritis (McDougall et al., 2002). Results also showed those In osteoarthritis, damage to cartilage can result in bony who switched to this type of diet experienced a significant growths developing around the edge of the joints causing reduction in symptoms. mild inflammation of the tissues (synovitis). Osteoarthritis mostly occurs in the knees, hips and small joints of the A further study showed that an uncooked vegan diet, rich hands. However, almost any joint can be affected. in antioxidants and fibre, decreased joint stiffness and pain in patients with rheumatoid arthritis (Hänninen et Osteoarthritis generally occurs in the over 50s and is al., 2000). Some studies have looked at fasting followed more common in women than men. However, it is not an by a vegetarian or vegan diet. A review of these studies inevitable part of getting older. It can develop after an concluded that this dietary treatment might also be injury to a joint; this can happen months or even years after beneficial for people with rheumatoid arthritis (Müller et al., the injury. 2001). Taken together, these studies provide strong evidence that dietary modification can benefit arthritis patients. Studies have been carried out to try to find whether omega-3 fats and/or fish oils can be helpful for Weight control osteoarthritis, but the results so far are inconclusive. It is widely accepted that it is important for people with arthritis to maintain a healthy weight. The extra burden on Rheumatoid arthritis the joints, in overweight or obese arthritis patients, can Rheumatoid (inflammatory) arthritis is a more aggressive, make symptoms considerably worse and losing weight can but less common condition than osteoarthritis. It is thought have a dramatic beneficial effect. to be an autoimmune disease whereby the body’s own immune system attacks the joints, causing pain, swelling The Arthritis Research Campaign (ARC) promotes medical and the destruction of bone and cartilage. research into the cause, treatment and cure of arthritic
16 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils conditions. ARC’s dietary guidelines for people with arthritis Omega-6 fats do not appear to benefit people with suggest that one of the most important links between diet arthritis. In fact they may increase inflammation by and arthritis is being overweight (ARC, 2006). competing with omega-3s (ARC, 2006). Most people have diets which already contain more omega-6 fats than they Adopting a plant-based based diet can help people lose need. If you have inflammatory arthritis, it may be helpful to weight and maintain a healthy body weight. Numerous replace some of the omega-6 fats (found in sunflower oil, studies show that vegetarians and vegans weigh less corn oil and products made from them such as sunflower than meat-eaters. A study of over 55,000 Swedish women margarines) with omega-3 fats from flaxseed, hempseed revealed that the vegetarian and vegan women were less and rapeseed oils and walnuts. Obtaining plant-based likely to be overweight or obese than the meat-eaters omega-3s from these sources will ensure you get this (Newby et al., 2005). In another study, the effects of a low- healthy fat without exposing your body to the harmful fat, plant-based diet on 64 overweight postmenopausal toxins found in oily fish. women was compared to a diet based on National Cholesterol Education Program guidelines (Barnard et Gout al., 2005). Results showed that the low-fat, vegan diet ARC warns that people with gout should not consume was associated with significant weight loss. A subsequent oily fish. Gout is a type of arthritis caused by a high level review of 40 studies revealed that, on average, vegetarians of urate in the body which can crystallise in the joints and and vegans weigh between six pounds and two stones less cause severe pain and inflammation. Urate is produced from than meat-eaters (Berkow and Bernard, 2006). purines, which are chemicals that result from the natural death of cells. Cutting down on foods which are high in When trying to lose weight, it is important to maintain purines may be helpful if you have gout. This is best done a good intake of nutrients. A healthy balanced diet by replacing animal-based foods (especially meat and fish) with other sources of protein, such as pulses (peas, beans, containing plenty of fruit and vegetables, pulses and and lentils). Other dietary measures for gout include losing wholegrain foods (wholemeal bread, brown rice and weight (if you are overweight) and avoiding excessive alcohol wholemeal pasta) provides a good supply of vitamins, consumption, which has been associated with gout for minerals and fibre. A diet lacking in these foods and rich centuries (ARC, 2006). in meat, dairy and processed foods (such as white bread, white rice and white pasta) does not provide such a good Calcium source of nutrients. Find out how to achieve and maintain a A well-balanced healthy diet can help you if you are taking healthy weight while protecting your health too in the VVF’s strong drugs for arthritis. In fact, ARC states that if you are V-Plan Diet guide. taking strong drugs for arthritis there is even more reason to eat a good diet as it can help to protect the body against Getting the fats right some of the side-effects of the drugs. For example steroids, ARC states that vegetarian diets have been shown to be such as prednisolone, can cause osteoporosis, particularly helpful in the long-term to some people with rheumatoid if you stay on them for a long time. Plenty of calcium in your arthritis. It also says that a vegan diet (no meat, fish or other diet will help to reduce the risk (ARC, 2006). animal products such as eggs, milk, cheese or other dairy products) may also be helpful (ARC, 2006). Conversely, Arthritis Care points out that people with rheumatoid arthritis studies have shown that people who eat large amounts are at increased risk of developing osteoporosis and agrees of red meat seem to have a higher risk of developing that ensuring an adequate calcium intake is very important inflammatory arthritis. (Arthritis Care, 2007). While cow’s milk and dairy products are indeed a source of calcium, they are not the best source. This The key point here is that not only is a plant-based is because they contain animal protein. Excessive amounts diet helpful because it contains beneficial substances of animal protein can upset the acid balance within the (antioxidants and omega-3 fats), but a typical Western diet, body, which then takes calcium from the bones to neutralise rich in meat, dairy and processed foods, is detrimental the acid. Even the usually pro-dairy National Osteoporosis as it contains high levels of harmful substances such as Society says: “It is a good idea to avoid too much protein, saturated fat. This unhealthy type of fat tends to come from particularly animal protein such as meat and cheese,” (NOS, animal-based food (particularly meat, poultry and dairy 2008). It is also a good idea to avoid too much salt, fizzy products) and processed foods (cakes, pastry and biscuits). drinks and caffeine for the same reason. This unhealthy fat is the most important kind to avoid as it can increase pain and inflammation in arthritis (ARC, 2006). Healthier sources of calcium include green leafy vegetables (broccoli, kale, spring greens, cabbage, parsley and Plant-based diets tend to contain considerably less watercress – but not spinach), dried fruits (figs and dates) saturated fat and more healthy polyunsaturated fats. The nuts (almonds and Brazil nuts), seeds (sesame seeds and research suggests that polyunsaturated omega-3 fats may tahini – sesame seed paste), pulses (peas, beans, lentils and help some people with arthritis and other inflammatory soya products such as calcium-set tofu and calcium-enriched conditions. The fact that people also tend to lose weight on soya milk). For more information on calcium see the VVF’s a vegan diet contributes further to its beneficial effects. fact sheet Boning up on Calcium.
17 Iron Omega-3s and arthritis Some arthritis sufferers may be concerned about their For some arthritis patients, omega-3 supplements may be iron intake, particularly – they may be told – if they avoid helpful, for example a tablespoon of flaxseed oil twice a eating red meat. This should not be a concern as the British day (this exceeds the 1 teaspoon-a-day recommendation Medical Association and the American Dietetic Association for normal consumption). If this is helpful, it may be a good agree that vegetarians are no more likely to suffer from iron idea to try to reduce your intake to the lowest effective deficiency than meat-eaters (BMA, 1996; American Dietetic dose. Association, 2003). Indeed one of the largest studies of vegetarians and vegans in the world (the EPIC Oxford Additional treatments cohort study) looked at over 33,883 meat-eaters, 18,840 Some arthritis patients have benefited from taking a vegetarians and 2,596 vegans and found that the vegans herbal remedy isolated from Rosa canina, a type of rose had the highest intake of iron, followed by the fish-eaters, hip (Winther et al., 2005). In a randomised, double-blind, vegetarians then the meat-eaters (Davey et al., 2003). Cow’s placebo-controlled trial, published in the Journal of milk and dairy products are an extremely poor source of Rheumatology, 82 per cent of patients reported a reduction iron, containing hardly any, whereas pulses, dried fruits and in pain after just three weeks of active treatment with dark leafy vegetables are all excellent sources. For more this herbal remedy. The authors of the study concluded information on iron see the VVF’s fact sheet Ironing out the that it could alleviate symptoms of osteoarthritis. In fact Facts. pain was reduced to such an extent that there was a significant decrease in the consumption of painkillers such Antioxidant action as paracetemol, ibuprofen and NSAIDs. This compares The antioxidant vitamins A, C and E are thought to protect favourably to glucosamine, currently the most popular against disease (and aging) by defending the body against supplement for joint health (Reginster et al., 2001; Matheson and Perry 2003). attack from harmful molecules called free radicals. These damaging molecules are produced naturally as your body Summary breaks down food, or as a result of exposure to harmful Losing weight, eating a healthy plant-based diet that chemicals (including cigarette smoke) or radiation. includes a good supply of omega-3 fatty acids (either though foods or supplements) can help reduce the The damage caused by free radicals plays a role in many symptoms of arthritis and may help some people reduce diseases including cancer and arthritis. A particular class of their medication (ARC, 2006). free radicals (called reactive oxygen species) can promote the inflammatory response that occurs in rheumatoid Multiple sclerosis arthritis (Filippin, 2008). A molecular mechanism linking In multiple sclerosis (MS), the protective sheath (called free radicals to inflammation has been proposed. It myelin) that surrounds the nerve fibres of the central suggests that free radicals activate molecules called nervous system becomes damaged. This process is called transcription factors (nuclear factor-kappa B or NF- B). demyelination. Sclerosis means scarring and multiple refers These then activate genes involved in inflammatory and/ to the many different sites at which the scarring may occur or autoimmune responses. In other words, free radicals can in the brain and spinal cord. Demyelination interferes cause a sequence of events rather like a line of dominos with the messages that are sent between the brain and falling down, which may lead to inflammatory arthritis. other parts of the body. Symptoms can include blurred vision, paralysis, slurred speech, lack of coordination and There is some evidence that anti-rheumatic drugs may incontinence. The severity of symptoms depends on how exert their therapeutic effects by acting as antioxidants. For much damage has occurred. example, non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to act as free radical scavengers (Merry et MS is the most common disease of the central nervous al., 1991). This means they may protect against the harmful system (the brain and spinal cord) affecting young adults effects of free radicals by ‘mopping them up’. However, in the UK. It currently affects around 85,000 people in the antioxidants may be more useful in preventing damage UK and can occur at any age, but in most cases symptoms before it occurs, rather than treating an already inflamed first appear between the ages of 20 and 40. Women are joint. almost twice as likely to develop MS as men. The majority of patients with MS have the relapsing-remitting form of the Too much iron in the blood can encourage the production disease, characterised by attacks or relapses interspersed of free radicals (McCord, 2004). Unlike the non-haem iron with periods of recovery or remission (Harbige and Sharief, we find in plant foods, haem iron in meat is absorbed 2007). It is a life-long condition, but it is not terminal and into the body whether it is needed or not. Thus meat can people with MS can expect to live as long as anyone else supply an overload of iron (but no vitamin C and very little (NHS Direct, 2008c). vitamin E). Conversely, vegetables and wholegrains foods can supply as much or as little iron as is required, as well as The cause of MS is not yet fully understood but is thought an abundance of protective antioxidant vitamins, fibre and to be an autoimmune disease (like rheumatoid arthritis other nutrients. or type 1 diabetes) whereby the body’s immune system
18 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils attacks its own tissues having ‘mistaken’ them for an distribution of MS and hypothesised that dietary fat intake invading (foreign) protein. This process is referred to as may contribute to progression of MS. ‘molecular mimicry’ as part of the foreign protein closely resembles part of certain cells in our own body. If this Swank suspected animal foods high in saturated fats may all sounds a bit complicated, just think of it as ‘friendly be responsible as MS seemed to occur most among inland fire’ – when a soldier mistakenly attacks one of his own. In dairy-consuming populations and less among coastal fish- autoimmune diseases, the body attacks itself. eating populations. His best known trial, published in the Lancet in 1990, followed 144 MS patients for a total of 34 As with other autoimmune diseases, it is thought that a years (Swank and Dugan, 1990). Swank prescribed a low- combination of genetic factors and environmental factors saturated fat diet to patients with relapsing-remitting MS causes the disease. There is undoubtedly an element of and observed how their conditions progressed. Results genetic predisposition in MS but the evidence suggests that showed that those who adhered most closely to the diet this disease is more strongly related to environmental factors derived the greatest benefits from the intervention. The than genes. In other words, a person may have a genetic beneficial effects were strongest in those who began to predisposition to the disease but not develop it unless follow the diet early in their disease. exposed to a specific environmental ‘trigger’. Such triggers may include bacteria, viruses or components of the diet. In 2000, 15 patients who had been on the diet for 50 years were re-assessed. Of these, 13 were able to walk without Geographical pattern difficulty, the other two required assistance with walking One of the most intriguing features of MS is that it occurs (Swank and Goodwin, 2003). Swank concluded that if people more in countries that are far from the equator. For example, with MS adhere to the diet, with no more than 10-15 grams MS is relatively common in the UK, North America and of saturated fat per day, they can expect to survive and be Scandinavia, but hardly ever occurs in countries such as ambulant and otherwise normal to an advanced age. Malaysia and Ecuador (NHS Direct, 2008c). The reason for this is not fully understood, but it could be that MS is Although Swank’s diet restricted meat and dairy foods, triggered by a particular bacteria or virus which thrives it did include fish and fish oils. More recently, another in cooler climates. Alternative theories suggest that study recommended a co-called ‘quasi’ vegan diet with components of particular foods consumed in these countries fish oil (McCarty, 2001). This study concluded that a may be responsible. whole-food vegan diet, coupled with fish oil and vitamin D supplementation, may represent a practical strategy for Diet and MS the prevention of autoimmune diseases, while concurrently Research suggests that some components in food can act as lowering the risk of many other life-threatening Western causative agents of autoimmune disease. For example, there diseases. Both regimes overlook the fact that you can have is strong evidence that proteins found in cow’s milk can an omega-3 rich vegan diet (containing ALA and an algal trigger an autoimmune response leading to type 1 diabetes supplement containing DHA and EPA if desired) without in genetically susceptible children. The theory with MS is exposing yourself to the toxins found in oily fish and fish that proteins from certain foods (such as cow’s milk) may also oils. prompt the immune system to respond inappropriately and attack the myelin sheath in the brain and central nervous Polyunsaturated fatty acids and MS system. A large body of evidence shows that populations Some research indicates that polyunsaturated fatty acids that consume high quantities of animal-based foods seem to (particularly omega-6 fats) have a role in the chain of be most affected by MS (Agnello et al., 2004). This inevitably events leading to, and the treatment of, MS. Studies show has drawn attention to the role of meat and dairy foods in that omega-6 levels are lower in MS patients. It has been the development of MS. suggested that the way omega-6 fatty acids are normally processed in the body is disrupted in people with MS. Numerous studies have revealed a striking association between the geographical pattern of MS and that of meat In a randomised, double-blind trial of a high dose and and dairy consumption (Arganoff and Goldberg, 1974; low dose omega-6 GLA-rich (borage) oil and a placebo Butcher, 1976; Lauer, 1994). There is also strong evidence control, the high dose had a marked clinical effect in linking a high intake of saturated fat to the incidence of relapsing-remitting MS. Results showed that the GLA- MS. Taken together, the evidence shows that foods rich in rich oil significantly decreased the relapse rate and the saturated fats are associated with higher levels of MS while progression of disease (Harbige and Sharief, 2007). The foods rich in polyunsaturated fats are linked to lower levels authors of this study suggested that disturbed omega-6 (Harbige and Sharief, 2007). fatty acid metabolism in MS gives rise to a loss of both long chain omega-6 fatty acids in the membranes and anti- The research investigating the links between diet and MS inflammatory cytokines, particularly during the dates back 60 years to Dr Roy Swank’s work first at the relapse phase. Montreal Neurological Institute in Norway, then at the Division of Neurology at the University of Oregon Medical The loss of these important neural fatty acids in central School in the US. Swank was intrigued by the geographical nervous system structure and function may have long-term
19 consequences in MS. However, this feature of MS can be nutrients required for good health and reduce some of the treated by supplementation (Harbige and Sharief, 2007). In risk factors for autoimmune diseases or prevent making an general, it appears that over time, diets low in saturated fat, already existing condition worse. but containing both some omega-6 and omega-3 fats, can improve the course of MS (Harbige and Sharief, 2007). As the incidence of most autoimmune diseases correlates directly to the consumption of animal foods, a move In 2007, a Cochrane review concluded that polyunsaturated towards a more a plant-based diet could help combat the fatty acids seemed to have no major effect on the main rise in these conditions among populations that currently clinical outcome in MS (disease progression) (Farinotti et consume high levels of dairy and meat products. al., 2007). However, only a limited number of studies was reviewed and they did state that the data available were Allergies insufficient to assess any potential benefit or harm from Some research suggests that the dramatic increase in the supplementation. Clearly more research is required to consumption of omega-6 fats, coupled to the decrease in assess the effectiveness of dietary interventions in MS. In the omega-3 fats consumed, is a major driver of the increase meantime, over 50 per cent of people with MS make dietary of a range of inflammatory allergic reactions (Chilton et al., changes and take supplements (Farinotti et al., 2007). 2008). Polyunsaturated fats and autoimmunity Asthma It is generally accepted that omega-6 fatty acids are pro- Asthma is a chronic inflammatory lung disease inflammatory (Harbige, 2003). However, while they have characterised by recurrent breathing problems. The UK has been shown to increase the severity of some autoimmune one of the highest prevalence rates for asthma in the world, and inflammatory diseases, omega-6 fats may actually along with New Zealand, Australia and Ireland. Around one protect against other (immune-mediated and non-immune- in eight children and one in 20 adults are currently being mediated) inflammatory diseases. Therefore, the view that treated for asthma in the UK. all omega-6 fats are pro-inflammatory is incorrect (Harbige, 2003). During an asthma attack, the lining of the airways becomes inflamed and the airways constrict. This can lead to the There is some evidence that omega-3 fats can ‘dampen characteristic symptoms of asthma such as coughing, down’ inflammatory responses. This anti-inflammatory wheezing, difficulty in breathing and tightness across the role may offer short-term benefits in some autoimmune chest. diseases. However, this could be an undesirable long- term effect of high-dose fish oils, as it could compromise The causes of asthma are thought to include a genetic immunity (Harbige, 2003). As stated earlier, the predisposition (asthma in the family) and environmental inflammatory response is a natural part of our immune triggers such as cigarette smoke, chemicals, dust mites and system and can help fight infection. In other words, a high diet. As food allergies are responsible for approximately intake of fish oils may not be beneficial in the long term; it five per cent of all asthma cases (James et al., 1994) and may weaken the immune system while only addressing the as cow’s milk is a primary cause of food allergies, it seems secondary consequences of an autoimmune response. reasonable to consider avoiding all cow’s milk and dairy products in the treatment of asthma. Diets low in saturated fat and relatively high in omega-3 fats (higher than the low amount present in most UK diets) Asthma may also respond to other dietary modifications, can reduce the severity of some autoimmune diseases. thereby reducing the need for medication. Studies show Conversely, diets high in the omega-6 fat LA may increase that supplementing the diet with plant-based fatty acids the severity of these conditions (Harbige, 2003). However, can inhibit inflammatory responses leading to asthma. One as stated previously, there is convincing evidence for a study found that supplementing the diet with omega-6 and protective role of both omega-6 and omega-3 fats in MS omega-3 fats in a ratio of 2:1 helped alleviate symptoms, (Harbige, 2003). whereas a ratio of 10:1 made symptoms worse (Broughton et al., 1997). In conclusion, moderate intakes of omega-6 fats and the appropriate ratio between omega-6 and omega-3 fats are Another study found that supplementing the diet with important for the correct functioning of the immune system borage oil (containing GLA) led to the accumulation of (Harbige, 2003). Adjusting the ratio could be helpful in natural inhibitors of leukotrines (hormones that cause the autoimmune or inflammatory disease. The optimum ratio symptoms of asthma) within inflammatory cells (Chilton et varies depending on age and the basis of the autoimmune al., 2008). This concurs with the research described above disease. that shows that GLA provides an exception to the usual pro- inflammatory role attributed to omega-6 fats. This all sounds rather complicated but the overall message is that a plant-based diet, low in fat, salt, sugar The overall optimum ratio of omega-6 to omega-3 fats may and processed foods and high in fresh fruit, vegetables, vary according the disease and the patient (age, sex and wholegrains, pulses, nuts and seeds can provide all the physical condition) but the message that we all need to
20 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils increase our intake of omega-3 fats while not increasing that Omega-3 fats have been identified as potentially helpful. of omega-6 fats is consistent throughout the research. Many people cannot tolerate the taste or smell of fish oils, even when provided in capsules. Because of this, and Eczema dwindling fish stocks, interest in plant-based sources of The increasing rate of eczema in the West has been linked omega-3 fatty acids has increased tremendously (Chilton et to a steep rise in the consumption of omega-6 fats and the al., 2008). reduced intake of omega-3s (Koch et al., 2008). Omega-6 fats favour the formation of specific eicosanoids (hormone- Most fat eaten in excess of requirements is stored in like molecules) that are involved in allergic inflammation. adipose tissue in the form of triglycerides (three fatty acids The parent omega-6 fatty acid LA is converted into combined with glycerol). Many diseases feature elevated arachidonic acid, a precursor in the production of levels of triglycerides: cardiovascular diseases, asthma, eicosanoids (Koch et al., 2008). Consequently an increased diabetes, obesity and arthritis. There is tremendous interest intake of omega-6 fats can promote allergic reactions, in plant-based oils and supplements (as an alternative to while increasing omega-3 intake competes with omega-6 fish oil) as a source of omega-3 fatty acids for protection metabolism and protects against inflammatory conditions. against these chronic diseases. Researchers from the Center for Botanical Lipids at Wake Forest University in The results of a recent exploratory trial were published in North Carolina state that botanical (plant-based) oils hold the British Journal of Dermatology (Koch et al., 2008). This particular promise for modulating inflammatory responses study reported how 53 patients suffering from eczema were (Chilton et al., 2008). randomly allocated supplements of both DHA and EPA, or a control (caprylic acid, otherwise known as octanoic acid, A large number of vegetarian and vegan studies show that an eight-carbon saturated fatty acid) daily for eight weeks. plant-based diets offer numerous health benefits, including Results showed a considerable improvement in the group the prevention and therapy of many chronic diseases taking DHA/EPA supplements. The authors suggested that including arthritis (Leitzmann, 2005). Since vegetarian and these fatty acids may have an anti-inflammatory role as they vegan diets are more sustainable, environmentally and inhibit arachidonic acid production. While some arachidonic economically, they certainly deserve more consideration acid is essential for your health, too much may make in both the prevention and treatment of disease. This inflammation worse. message needs to filter down from the peer-reviewed studies into our hospitals, schools, workplaces and homes. It was noted that plasma DHA and EPA levels rose two- to threefold following supplementation. The authors Brain food suggested that the higher level of EPA might have resulted The human brain grows and develops very rapidly during from the small but significant amount of EPA in the the first year of life, tripling in size by the age of one. The supplement or from the retroconversion of DHA to EPA. brain is largely made up of fat (over 60 per cent) and early This is important as it indicates that an algal supplement brain development and function in humans requires a supplying DHA could be used to increase both DHA sufficient supply of polyunsaturated EFAs. For humans, the and EPA levels. Again this means you could take an algal omega-6 fat arachidonic acid and the omega-3 fat DHA are supplement and avoid the risk of exposing yourself to toxins essential for brain development and functioning. that may be found in fish oil supplements. Although human breast milk and cow’s milk contain a Summary similar amount of total fat, the proportion of saturated and Our genes take a very long time to change and are still very unsaturated fats in each is very different. This difference similar to the genes of our ancestors during the Palaeolithic contributes to the unsuitability of cow’s milk for human era 40,000 years ago, when the human genetic profile infants. The high level of unsaturated fats in human breast was established (Simopoulos, 2008). The same cannot be milk reflects the crucial role these fats play in human said for our diet. Anyone can see our diets have changes brain development. A rapid increase in body size is more hugely – our ancestors would have been hard pushed to important for cows, so they produce milk high in body- find burger, chips and a milkshake! But does this matter? building saturated fats to help their calves grow quickly. Well, studies on the evolutionary aspects of diet indicate that the major changes that have occurred have altered A review of 20 studies of cognitive (brain) function of the type and amount of essential fatty acids in our diets breast-fed infants compared to that of formula-fed infants (Simopoulos, 2008). So while in many ways our bodies are concluded that the nutrients in breast milk may have a potentially the same as those of our ancestors, the way we significant effect on neurological development in infants fuel it has changed drastically. This is like expecting a car (Anderson et al., 1999). Indeed, a longer duration of to run on a lower grade fuel than it was designed for. There breastfeeding is associated with significantly higher scores will inevitably be problems with the engine. in verbal, performance and IQ tests (Mortensen et al., 2002). So breast really is best! The increase in heart disease, arthritis, allergies and other health problems has encouraged some scientists Attempts to alter the fatty acid composition of cow’s to investigate the role of diet in these and other diseases. milk, in order to meet human requirements, have involved
21 experiments feeding cows fish meal and soya beans (Abu- 80 per cent fish oil and 20 per cent evening primrose Ghazaleh et al., 2004) and flaxseed (Petit, 2002). Feeding oil in gelatine capsules. The daily dose of six capsules flaxseed resulted in a lower omega-6 to omega-3 fatty acid provided omega-3 fatty acids (558 mg of EPA and 174 mg ratio, which might improve the nutritional value of milk for of DHA) and the omega-6 fatty acid LA (60 mg), or olive oil humans. Of course you could just eat flaxseed oil yourself to (omega-9) as a placebo. improve the balance of omega-3 and omega-6 oils in your diet while avoiding the many undesirable components of After three months of treatment, results showed significant cow’s milk and oily fish. improvements in reading, spelling and behaviour among those receiving the fish oil supplements. The researchers Smart enough to be veggie? concluded that fatty acid supplements may be a safe, Fish oils have been sold as a magic bullet for boosting tolerable, effective treatment for improving academic brain power. As the term ‘essential’ implies, we certainly progress and behaviour among children with DCD. In other do need some EFAs in the diet. However, contrary to the words, children who are not fulfilling their potential may intensive and misleading marketing, fish and fish oils are benefit from increasing their intake of essential fatty acids. not essential for good health. In fact, the fatty acids found The VVF asked the researchers in Durham if they would in fish oil (EPA and DHA) are not defined as ‘essential’; only consider using flaxseed oil in future trials to see if similar the plant-based fats ALA and LA are. These plant-derived results could be achieved without exposing children to EFAs provide a healthier and safer source. Consider this: if potential toxins but our requests were ignored. fish oils were a superior source of fatty acids for brain health then vegetarians would come bottom of the intelligence A follow-up trial was conducted in Durham more recently stakes. The reverse appears to be the case. whereby three million fish oil capsules were given to 2,000 children over eight months to see if their GCSE results Links between intelligence and the vegetarian diet were improved. Unfortunately the GCSE results were rather demonstrated in 2006 when a team of vegetarians won the disappointing, which was not press-released by the County BBC’s Test the Nation IQ battle (the butchers came joint Council. In some very fast back-pedalling they said “...it was fourth; sadly there was not a team of fish-mongers!) never intended, and the County Council never suggested, that it would use this initiative to draw conclusions about More weighty evidence was provided in a study published the effectiveness or otherwise of using fish oil to boost in the British Medical Journal which showed that intelligent exam results.” So it seems fish oil was not the magic bullet children are more likely to become vegetarians later in Durham Council was looking for. life (Gale et al., 2007). Researchers from Southampton University found that people who are vegetarians by the It is interesting to note that the fish oil capsules used in the age of 30 had an IQ five points higher than the average IQ Durham trial cost 80p per child, per day, rather more than when they were 10. This might explain why people with a the 65p Durham Council was spending per child per day higher IQ are healthier: vegetarians generally suffer less on school meals at the time. In 2008 the cost of ingredients heart disease, hypertension, obesity, diabetes, various had risen, but to just 80p for a secondary school child per cancers, diverticular disease, bowel disorders, gallstones, day (Durham Council, 2008). Rather than looking for a magic kidney stones, and osteoporosis. bullet, improving the quality of school meals and education about diet and health would perhaps have been a better The obvious point here is that if omitting fish and fish oils approach. from the diet led to a lower cognitive ability, non-fish eating children and adults would come bottom in the intelligence Most children in the UK eat such appalling diets that stakes. There has never been any study to suggest this is nutritional deficiencies are inevitable. Correcting such the case and thousands of healthy intelligent vegetarian deficiencies will in many cases improve the symptoms and non-fish eating families provide proof that brains associated with that particular deficiency. This is not the function perfectly well without fish oils! same as saying fish oil will turn all kids into geniuses, which is exactly how the media interpreted the findings. ‘Council Fish oils for brainy kids? to include more fruit, vegetable and wholefoods in school So what is the scientific evidence that fish oils can improve meals’ just doesn’t make such an impressive headline as cognitive ability and where does the Government stand ‘magic pill makes kids clever’. on this issue? The evidence comes mainly from trials done using children with behavioural problems and is largely The Joint Health Claims Initiative (JHCI) operated between anecdotal. 2000 and 2007 to ensure a level playing field for the food industry and to increase consumer protection by The Durham-Oxford Study is the most cited work investigating the science behind health claims (JHCI, (Richardson and Montgomery, 2005). In this study, 117 2007). It is no longer in operation as the new EU ‘claims’ children with developmental coordination disorders (DCD) regulation for foods now verifies health claims. However, such as attention deficit/hyperactivity disorder (ADHD), during the seven years of investigating health claims, the dyslexia and dyspraxia were given a daily supplement of JHCI approved claims for soya protein, oats and reduced fatty acids. The treatment was a supplement containing saturated fat all for their cholesterol-lowering effects and
22 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils for wholegrain foods’ benefits to heart health. They also bigger fish eats smaller fish and so on. Fish at the top of the approved health claims for long chain omega-3 fats for food chain such as tuna, shark, swordfish, tilefish and king maintaining a healthy heart. They did not approve any mackerel, have the highest concentrations of POPs. Algae claims linking omega-3 fats (or fish oils) to cognitive ability. (which are right at the bottom of the food chain) are likely to contain much lower levels. Unfortunately misleading publicity from this and other research has encouraged companies to produce so-called Farmed salmon are even more of a concern than wild functional foods such as St Ivel Advance Omega-3 milk. The salmon due to the concentration of POPs in the feed advertisements implied that this milk may make children they eat and their fatty nature as POPs can accumulate in more intelligent because it contained omega-3 fatty acids fatty tissue. (from fish). The advertisements for this so-called ‘clever milk’ featured the scientist Professor Robert Winston, In 2001, officials from 90 countries signed a landmark lending kudos to the outlandish claims. But following UN treaty in Stockholm, designed to curb the use of complaints, the Advertising Standards Authority (ASA) ruled some of the world’s most dangerous and toxic chemicals that the advertisements were misleading and the claims (Stockholm Convention, 2008). They identified twelve used for the benefits of the milk unproven. The ASA ruled particular substances for banning which later became that as the children in the trial had learning difficulties, there known as the ‘dirty dozen’. The list included eight organo- was no basis to claim there would be an improvement in the chlorine pesticides: aldrin, chlordane, DDT, dieldrin, endrin, concentration of all children. Dairy Crest, the firm behind heptachlor, mirex and toxaphene; two industrial chemicals: the product, withdrew the adverts following the ruling. hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs); and two groups of industrial by-products: dioxins Although the Government has refused to shift its position and furans. on recommending fish oils for heart health, it is clearly not convinced about cognitive benefits. The FSA states that: The Stockholm Convention on POPs came into force on “Evidence on the cognitive benefits of the omega-3 fatty May 17, 2004, with agreement from an initial 128 parties acids, EPA and DHA, which are found in fish oils, is currently and 151 signatories. Co-signatories agreed to ban nine of uncertain,” (FSA, 2008). the ‘dirty dozen,’ limit the use of DDT to malaria control and curtail production of dioxins and furans. Several other Common sense suggests that if the diet provides enough substances are now being considered for inclusion in the EFAs, fish oils may have no additional effect on cognitive Convention. These are: hexabromobiphenyl, octaBDE, ability at all. Encouraging children to eat oily fish in the pentaBDE, pentachlorobenzene, short-chained chlorinated pursuit of cleverness may lead to serious health problems paraffins, lindane, - and -hexachlorocyclohexane, dicofol, due to their exposure to pollutants. endosulfan, chlordecone and PFOS. Not what you’d expect to see in a list of ingredients! However, even though this is a step in the right direction, Contaminated fish are a danger to health it will take many years for POPs (used in everyday items such as plastics, paints and pesticides) to break down. All of the world’s oceans and rivers are polluted with toxic Furthermore, the environmental group, the World Wildlife chemicals; mainly pollutants resulting from decades of Fund has expressed concerns that global warming could increasing industrial activity. The health risks associated increase levels of POPs as higher temperatures may release with the consumption of fish and fish oil supplements chemicals which have been frozen in glaciers. are due to the presence of these toxic pollutants, not to mention the saturated fat, animal protein and cholesterol PCBs they contain. Oily fish such as salmon, trout and mackerel Polychlorinated biphenyls (PCBs) and dioxins are the main may be contaminated with chemicals, while shark, marlin contaminants in oily fish (Consumers’ Association, 2002). and swordfish contain high levels of mercury (Consumers’ Although they are now banned, PCBs have not disappeared Association, 2002). Long-term exposure to these harmful from the environment and won’t for a very long time. substances poses a significant threat to health. The Scientific Advisory Committee on Nutrition (SACN) POP goes the seawall is an advisory committee of independent experts that A particularly nasty class of contaminants found in oily fish provides advice to the FSA, Department of Health and is known as persistent organic pollutants (POPs). These other government agencies and departments. SACN organic pollutants are made up of complex molecules states that: “PCBs are very persistent chemicals which are which do not break down easily in the environment; hence ubiquitous in the environment and are generally present in the name ‘persistent’. They build up in the food chain low concentrations in foods, especially fat-containing foods through bioaccumulation. This means that the level of including milk, meat and fish,” (SACN, 2004). chemicals found in an animal tissue rises the higher up the food chain the animal is. For example, larvae might eat As persistent lipophilic (fat-loving) compounds that some contaminated algae, a fish then eats the larvae, and a accumulate in lipids, PCBs are particularly likely to be present
23 in oily fish. They are implicated in heart disease, cancer, in antioxidant reactions. Sulfhydryl groups are compounds infertility and can harm developing foetuses by disrupting that contain a functional group composed of a sulphur atom the development of male babies’ reproductive organs. and a hydrogen atom (-SH). They feature as a functional group of the amino acid cysteine and so play an important Dioxins role in many biological systems. By binding to sulfhydryl Dioxins were the primary ingredient in Agent Orange, groups, mercury inactivates antioxidative compounds, the defoliant sprayed over Vietnam which has produced again, increasing free radical activity. Taken together, these an appalling legacy of cancers and other diseases, reactions indicate how mercury could inhibit important miscarriages and birth defects. As stated, these insidious antioxidative mechanisms in humans. In other words, the toxins build up in the body over time. The FSA points out high mercury content in fish can not only counteract the that: “If a woman changes her diet when she becomes protective effects of the fatty acids found in oily fish, but pregnant, or when she starts trying for a baby, this won’t may go on and do serious harm to health. change the levels of dioxins and PCBs that are already in her body. So it’s a good idea to limit the amount of oily fish For non-oily fish, there seems even less reason to take the eaten from a young age.” risk of exposing yourself to mercury. Numerous studies have reported an association between fish intake and coronary Furthermore, contrary to previous advice that these toxic mortality. In 1995, one study investigated why men in pollutants are only found in oily fish, the FSA states that: Eastern Finland have an exceptionally high level of mortality “Recent surveys have shown that some other fish and crab from CVD (Salonen et al., 1995). This study measured hair may also have similar levels of dioxins and PCBs as oily fish. mercury content in healthy individuals and then recorded These fish are: sea bream, turbot, halibut, dog fish or huss, CVD events (such as heart attacks) over the following years. and sea bass.” Now they tell us! The mercury content in Finnish lakes is known to be Mercury rising relatively high; especially so in ground waters (water that Methylmercury is the organic form of mercury found in supplies wells and springs) in Eastern Finland. This study the environment, usually as the result of industrial pollution. found that an average daily fish intake of just 30 grams This toxin is commonly found in the marine environment or more was associated with a two-fold increase in heart and accumulates up the food chain particularly in older, attack risk. For each additional 10 grams of fish per day larger fish. Mercury affects the kidneys, heart and central there was an increment of five per cent in the five-year risk nervous system (CNS). Exposure is particularly hazardous of heart attack. This indicates that mercury, even in subtoxic for unborn children where the main organs and the CNS amounts, is a risk factor for coronary and fatal CVD. The are still developing. Women and girls who may have authors concluded that because in many countries fish children one day are advised to eat less oily fish than and seafood are contaminated with mercury and because men and older women because mercury can harm the fish is eaten all over the world, their findings could be of development of unborn children. The FSA states that adults enormous public health importance. should have no more than one portion of swordfish, shark or marlin a week because these fish contain high levels of A later study (from the same group) investigating the mercury (FSA, 2009). association between blood levels of the omega-3 fats EPA and DHA, and the risk of acute coronary events in middle- While some studies indicate that high intakes of oily fish, aged men from Eastern Finland, again looked at mercury or fish oil supplements, are associated with a reduced levels in hair (Rissanen et al., 2000). This prospective risk of CVD, others have suggested that fish oils can population-based study of 1,871 men confirmed that increase the risk. In these studies, mercury is suspected high levels of DHA in the blood were associated with a as being responsible for the harmful effects seen as it can decreased risk of acute coronary events. However, the accelerate atherosclerosis and increase the risk of heart men who fared best in this comparison were those with attack. Possible mechanisms by which mercury exerts these high DHA levels and low mercury content in the hair. It damaging effects include promoting the peroxidation of was concluded again that mercury could cancel out any unsaturated fatty acids (Salonen et al., 1995). This is the protective effect offered by the fats in oily fish. process whereby damaging molecules called free radicals ‘steal’ electrons from the fats in cell membranes, resulting A case-controlled study published in the New England in cell damage. Journal of Medicine in 2002 conducted in eight European countries and Israel provided further evidence linking Mercury also forms an insoluble complex with the mercury in fish to CVD. This study investigated the antioxidant mineral selenium. It binds it in an inactive relationship between mercury levels in toenail clippings form preventing selenium from acting as a cofactor for the and DHA levels in adipose tissue with the risk of a first heart protective enzyme glutathione peroxidase. This enzyme’s attack among men (Guallar et al., 2002). This study included main biological role is to protect the body from oxidative 684 men in the coronary care units of participating hospitals damage. Binding selenium in this way can lead to an who had experienced their first heart attack. Also, 724 men increase in free radical activity. Mercury also has a very high representative of the same population (but who had not affinity to sulfhydryl groups which play an important role had a heart attack) were selected to act as controls. Results
24 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils showed that while higher DHA levels were associated with group over another. This has lead to a failure to pay enough a lower heart attack risk, the toenail mercury level was attention to the role of contaminated fish and shellfish in directly associated with an increased risk of heart attack. food poisoning. The authors of this study suggest that The authors concluded that mercury may diminish the relying solely on the literature has lead to an over-emphasis cardioprotective effect of fish intake. on controlling the milk supply and a failure to pay enough attention to the role of contaminated fish and shellfish in They also warned that exposure to mercury is already food poisoning. a concern in specific high risk groups and suggested extending the US Food and Drug Administration’s When they are raw or haven’t been cooked properly, fish and recommendation that pregnant women and women who shellfish can contain a range of harmful viruses and bacteria. may become pregnant do not eat swordfish, king mackerel, Shellfish (such as clams, mussels and oysters) are also filter tilefish or tuna to include the entire population. feeders, constantly filtering water, which can lead to the accumulation of pollutants. The FSA recommends that elderly A statement from the American Heart Association people and people who are unwell might want to avoid (AHA) acknowledges the discrepancy in the findings of eating raw shellfish to reduce their risk of food poisoning research on fish oils and CVD (Kris-Etherton et al., 2002). (FSA, 2008d). Most shellfish is eaten cooked, but oysters are They acknowledge that the contradictory findings of often served raw and can contain a virus called the Norovirus. these studies could be explained by the adverse effects Raw or partially cooked shellfish can also contain hepatitis A, of mercury, which they say may diminish the health which is a highly contagious virus of the liver. benefits of omega-3 fatty acids from fish. They conclude that while collectively, the research is supportive of the For these reasons, the VVF argues that sea vegetables recommendation to include at least two weekly servings of (seaweed) are the true ‘fruits de mer’ or fruits of the sea, not fish (particularly fatty fish), this recommendation must be shellfish. Not only do they add flavour to food, each variety balanced with concerns about environmental pollutants, in is a low-fat nutritional powerhouse, packed full of vitamins particular PCB and methylmercury. This ambiguity can only and minerals. Plus, you won’t find elevated levels of dioxins, add to the confusion! PCBs or mercury in sea vegetables, in contrast with fish and shellfish in whose body fats these pollutants accumulate They do however point out that the research supports the over time. inclusion of vegetable oils (soya bean, rapeseed, walnut and flaxseed oils) and food sources (walnuts and flaxseeds) high The FSA’s website provides an extensive list of in ALA in a healthy diet for the general population. This, at precautionary measures people should take when buying, least, is a move in the right direction. storing and preparing fish. It lists 18 different ways you can minimise the risk of being poisoned (FSA, 2009). Of Food Poisoning course just avoiding fish and shellfish would be much Food poisoning generally happens when someone eats easier. Indeed excluding all animal foods from the diet will food that is contaminated with bacteria or its toxins. dramatically decrease the risk of food poisoning. According to the FSA, it is estimated that up to 5.5 million people in the UK are affected by food poisoning each year Fish and PhIPs (NHS Direct, 2008d). However, it is difficult to know exactly Most people think the fool-proof way to avoid food how many people are affected as not all of those affected poisoning from meat and fish is to cook it very well – some seek medical advice. people practically cremate it to make sure. However, thoroughly cooking meat and fish can lead to even more Most cases of food poisoning result from eating serious problems. contaminated animal products (meat, poultry, eggs, dairy, fish and shellfish) as plants tend not to harbour the types of Cancer-causing compounds called heterocyclic amines bacteria capable of causing food poisoning in humans. If (HCAs) are formed when meats (such as beef, chicken and plant foods do cause food poisoning it is generally because pork) and fish are cooked at high temperatures (Wilson et al., they have been contaminated with animal excreta, human 2007). HCAs form when a chemical found in muscles called sewerage or prepared with dirty hands. creatine reacts with amino acids (the building blocks of protein) and sugar at high temperatures. While meat While most food poisoning incidents are associated with and fish contain significant amounts of creatine, vegetables meat and poultry, the links between fish, shellfish and contain none. food poisoning should not be discounted. Researchers from the Health Protection Agency Centre for infections In 2005, the US federal government officially added HCAs in London looked at a number of cases of food poisoning to its list of known carcinogens (US Department of Health in the UK between 1992 and 2003 (O’Brien et al., 2006). and Human Services, 2008). The most abundant HCA Of the 1,763 cases reported to national surveillance, only found in the human diet is called 2-amino-1-methyl-6- 55 were published in the peer-reviewed literature. As this phenylimidazo[4,5-b] pyridine (PhIP). PhIP is associated with type of publication tends to favour the unusual or novel an increased risk of cancer of the colon, breast and prostate event, coverage can lead to an over-emphasis of one food (Wilson et al., 2007).
25 Exactly how PhIP increases cancer risk is uncertain. It has per day. Providing a similar diet to farmed fish would mean been suggested that PhIP produces harmful molecules grinding up to 10 pounds of sardines, anchovies, mackerel, called reactive oxygen species which cause DNA strands herring and other fish for every pound of pale and sickly to break thus increasing cancer risk (Wilson et al., 2007). farmed salmon produced. This is clearly uneconomical for Alternatively, researchers at Imperial College in London fish farmers and heralds an ecological disaster as one-third have reported that PhIP is a potent mimic of the hormone of the global fish catch ends up as fishmeal or fish oil and oestrogen (Lauber et al., 2007). This is very worrying, as fish farms use about half of the fishmeal and more than 80 many studies link higher oestrogen levels to breast cancer. per cent of the fish oil (Soil Association, 2008). This theory provides a plausible explanation for why diets rich in red meats are linked to an increased risk of breast It is much cheaper to manufacture feed pellets from soya, cancer. rapeseed or corn with animal by-products and vitamin and mineral supplements. In Canada and Chile, it is common to In 2005, the Physician’s Committee for Responsible use other protein sources such as feather or blood meal by- Medicine’s Cancer Project revealed that grilled salmon was products of chicken and pig production (Soil Association, among the five worst foods to grill (PCRM, 2005). The Cancer 2008a). Consequently, farmed fish tend to contain more Project nutritionists found that many commonly grilled total fat, but less omega-3s than their wild counterparts foods contain alarmingly high levels of HCAs. The five foods (Weaver et al., 2008). In other words, the levels of good and containing the highest levels included: chicken breasts, steak, bad fats (the fatty acid profile) of farmed fish vary widely pork, salmon and hamburgers. from that of wild fish. The amount of PhIP in some foods may typically lie in the Using cheaper vegetable-based feeds drives up the level region of 35 nanograms per gram. However, there are of omega-6 fats found in the fish. Farmed tilapia (the some reports of much higher levels of PhIP (Skog, 2002). most rapidly expanding fish in terms of world and US Concentrations of PhIP in fish vary widely according to consumption), contain some of the highest levels of the the type of fish and method of cooking. One study reported omega-6 fatty acid arachidonic acid found in our food levels ranging from 1.7 to 73 nanograms per gram in salmon chain (Weaver et al., 2008). These and other farmed fish cooked at 200°C by various methods (Gross and Grüter, 1992). have a fatty acid profile that would generally be considered as unhealthy. Indeed, marked changes in the fishing The damaging action of HCAs may be reduced by foods industry during the past decade have produced widely containing antioxidants, such as vegetables and soya foods eaten fish that have fatty acid characteristics that are (Weisburger, 2002). However, the safest option is to avoid generally accepted to be inflammatory by the health care meat and fish altogether. Healthier options for grilling and community (Weaver et al., 2008). frying include soya burgers, veggie sausages and Portabella mushrooms. The fish used in organic fish feeds come from the discarded filleting wastes (blood, guts, tails and heads) of fish caught for human consumption and should not contain fish caught specifically for fish feed. However, this does mean the Farmed and dangerous supply is sustainable; human demand for fish also exceeds supply. Compared to conventional fish feed, organic fish Unless you seek out wild fish, the chances are that most of feed may use more fish-based ingredients than non-organic the fish you see in shops and restaurants were raised on a fish feed but still might only have 40 per cent fishmeal and fish farm in an environment very different to what their wild about 22-25 per cent fish oil (Soil Association, 2008a). This counterparts would have experienced. One of the main means that 35 per cent of the feed could be vegetable- differences on many fish farms is the stocking density – based. imagine having to fight your way through the January sales every day just to get something to eat. This is the type of Farmed fish can also contain chemical pesticide residues scenario many farmed fish endure. as well as dangerous levels of toxic man-made chemicals including PCBs. A 2002 study investigating the levels of Fish species raised by fish farms include salmon, catfish, toxins in commercial salmon feeds, farmed salmon and tilapia, cod, carp, trout and others. Just as we see with wild salmon found that the farmed salmon had consistently other farmed animals such as the dairy cow, intensive higher levels of a range of contaminants including farming methods results in a cheaper end product (in PCBs (Easton et al., 2002). The authors suggested that terms of quality and price). This is why farmed salmon has the higher levels seen in the farmed salmon probably been called ‘the battery chicken of the seas’. This may not resulted from the elevated level of contamination found concern you if the supposed health benefits are the same. in the commercial salmon feed. They concluded that this However, they are not. analysis indicates a safety concern for individuals who, on a regular weekly basis, consume farmed salmon produced From a nutritional and health perspective, there are several from contaminated feed. Since then, other studies have important differences between farmed and wild fish. In indicated that commercial feed is likely to be a major the wild, salmon can eat 10 times their own body weight source of PCBs in farmed salmon (Carlson et al., 2005).
26 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils So, farmed fish are very far from the safe choice we are occasionally eating more than the recommended amounts led to believe and from a health perspective, when fish of oily fish will not be harmful. It says that the risks from are farmed, they lose some of their protective fats. This is chemicals such as dioxins are not immediate; they develop a ridiculous situation where the one possible argument in as the chemicals accumulate in the body over a long favour of fish consumption (their omega-3 content) is being period of time. Surely it is better to avoid these hazardous eroded by intensive farming methods. There remains little, chemicals altogether? if any, argument for consuming fish. Confused? You will be! The FSA advises that fish oils protect against CVD and that long chain omega-3s are vital for the development of the Fish oil supplements central nervous system of the foetus and the breast-feeding infant (SACN, 2004). However, the FSA warns pregnant Some people prefer to take fish oil supplements rather than and breast-feeding women to restrict their intake of oily eat oily fish. However, fish oil supplements have also been fish to limit their exposure to harmful toxins. So just when linked to negative health effects in numerous studies. This your intake of omega-3 really matters, during pregnancy is particularly worrying as they are increasingly popular as and when you are breastfeeding, the Government warns clever marketing persuades people to buy them. you to limit your intake! Consumers are unsurprisingly confused; the information given is neither comprehensive Most fish oil supplement manufacturers publicise their nor consistent. meticulous manufacturing techniques reassuring us that all toxins are removed from their products. However, in March In 2002, Which? magazine reported the findings of a 2006, the FSA announced that the fish oil supplement Consumers’ Association survey which asked 972 adults manufacturer Seven Seas Ltd withdrew a number of about their awareness of, eating habits and attitudes to batches of its own fish oil supplements because the levels oily fish (Consumers’ Association, 2002). The survey found of pollutants present (FSA, 2006). Less than a month later that only a sixth of fish-eaters knew that the FSA’s advice Boots withdrew fish oil capsules for the same reason (FSA, is to eat oily fish once a week; over half thought the advice 2006a). In both cases they said although there was no was to eat two or more portions. A shocking 61 per cent of health risk associated with consumption of this product, people had no idea that oily fish may contain contaminants. the level of dioxins found in fish oil used to produce One per cent knew that pregnant women should avoid these capsules exceeded statutory limits. This is a bizarre certain fish but nobody could name them. Most people in statement which seems to be saying that a little bit of the survey were confused by what was meant by oily fish poison should be all right! (14 per cent thought that cod was an oily fish). It is not just the public who are confused; the Consumers’ Association states that the FSA couldn’t provide any clear answers about the health implications of eating more than one The official position – not budging portion of oily fish per week. The seriousness of the potential health risks of consuming toxins in fish prompted a joint subgroup of two advisory It’s no clearer in the US. In 2002 the American Heart committees, the Scientific Advisory Committee on Association (AHA) issued a statement supporting Nutrition (SACN) and the Committee on Toxicity the recommendation for at least two servings of fish of Chemicals in Food, Consumer Products and the (particularly oily fish) per week (Kris-Etherton et al., 2002). Environment (COT), to consider the benefits and risks of However, the AHA warned that the recommendations fish consumption (SACN, 2004). on fish consumption need to be balanced with concerns over contamination of fish with environmental pollutants Their report formed the basis of the FSA advice that (particularly mercury and PCBs). This is an incredibly pregnant and breastfeeding women should limit their important proviso which seriously challenges the idea consumption of oily fish to one to two 140 gram portions that fish is ‘healthy’. It should be noted that the AHA per week. This group (and children under 16) they say, also recommended plant foods that are high in the plant should avoid shark, marlin and swordfish and not eat large omega-3 ALA such as soya beans, rapeseed, walnuts and amounts of tuna because of the potential methylmercury flaxseed and oils made from them. exposure. Men, boys and women past childbearing age or who are not intending to have children can eat up to four In the joint WHO/FAO 2003 report Diet, Nutrition and portions of oily fish a week before the possible risks might the Prevention of Chronic Diseases, regular fish start to outweigh the benefits. consumption of one to two servings per week is recommended to protect against CVD (WHO/FAO, 2003). The report highlights the presence of dioxins in herring, However, whilst it also states that vegetarians can ensure salmon, mackerel and to a lesser degree in trout, and adequate intakes of the omega-3 fatty acid ALA from plant voices concerns about the presence of other pollutants sources, the report fails to give any warnings about the such as brominated flame retardants. The FSA states that dangers of environmental contamination.
27 This conflicting advice has led to much confusion. Who EFAs, such as nuts and seeds, possess their own supply of should the public listen to? Who can they believe? antioxidants which protect their fats (in particular vitamin E). So yet again, we see why a plant-based diet provides not Fish is not a popular food only important nutrients, but valuable substances that can Despite the constant barrage of fish-promoting marketing protect us from oxidative damage too. and hype, the UK public just don’t buy it! The FSA says that on average, people in the UK eat only a third of a portion Free radicals are a problem for us too! They are unstable of oily fish a week (FSA, 2004). Indeed, fish is so unpopular molecules generated by normal bodily functions, cigarette that the FSA admits that seven out of 10 people in the UK smoke, pollution, ultraviolet light and stress. Free radicals don’t eat any oily fish at all. Clearly then, oily fish is not a are linked to cancer or other diseases as well as the aging significant contributor of omega-3 fatty acids in the diets of process. Animals and plants protect themselves against free many people. radicals with antioxidants. They are a natural self-defence mechanism which is thought to defend against many From a public health perspective, encouraging people to diseases in humans, including the UK’s biggest killers heart eat more fish in order to gain healthy amounts of omega-3 disease and cancer. fats is simply not working. Even if people did start to consume more, the oceans simply cannot cope with any As stated, the three amigos of the antioxidant world more demand, and as we have seen, farmed fish is definitely are beta-carotene (vitamin A), vitamin C and vitamin E. not the solution. The mineral selenium is another valuable antioxidant. Antioxidants are not found abundantly in meat or fish. Plant The upshot of all this confusion and dislike for fish is that foods (including fruit, vegetables, nuts and seeds) are the many people fail to understand the importance of omega- best sources. In the largest, most comprehensive analysis 3s and do not realise how easy it is to obtain them from to date of the antioxidant content of commonly consumed every-day plant foods. Promoting oily fish as the only ‘heart foods cranberries, blueberries and blackberries ranked friendly’ solution could actually deter individuals from highest among the fruits studied. Beans, artichokes and making the fundamental dietary changes necessary for real Russet potatoes topped the list of vegetables. Pecans, long-term heart and body health. A healthier and simpler walnuts and hazelnuts were the top nuts and ground cloves, solution would be to promote a plant-based diet containing cinnamon and oregano ranked highest among the herbs EFA-rich seeds, nuts and oils. Plants, not fish, are the way and spices (Wu et al., 2004). As a general rule, brightly forward for good health. coloured vegetables (such as sweet potatoes, red cabbage and tomatoes) tend to be relatively high in antioxidants. Again, vegans are in a win-win situation. Not only do they Plant EFAs leading the way to good health avoid harmful substances found in meat and fish, they also benefit from a wide range of healthy nutrients including The good news is you don’t have to eat neurotoxins and fibre, vitamins, minerals and of course, antioxidants. carcinogens to get your omega-3 fatty acids; there are perfectly safe plant sources that can benefit your health. Antioxidants in plants protect EFAs Sustainability The antioxidant vitamins C, E and beta-carotene (the precursor of vitamin A) are found in abundance in plant The widely publicised supposed health benefits of omega-3 foods such as fresh fruits, vegetables, nuts and seeds. They fats from fish, together with dwindling supplies of fish are thought to be one of the body’s main defences against caught from the wild, have spawned a dramatic expansion damaging molecules called free radicals. They are also vital in aquaculture (farmed fish). Aquaculture has increased at for another important function that demonstrates why plant an annual rate of 9.2 per cent compared with 1.4 per cent for sources of fatty acids are superior to fish-derived versions. caught fish (Weaver et al., 2008). Most people (especially those who cook a lot) know Nearly half the fish consumed as food worldwide (43 per that certain fats are more likely to ‘go off’ when they are cent) is raised on fish farms rather than caught in the wild; exposed to air. The difference arises from the number of that’s up from just nine per cent in 1980 (FAO, 2006). The double bonds in the fat as they make fats vulnerable to level of fish caught in the wild (around 90-93 million tonnes attack from oxygen molecules. This is why we cover food annually) by contrast, has not changed much despite with plastic wrap or submerge it in water to protect it. growing world population and demand. It can’t. The FAO This is why fish oils are prone to oxidation and give off a acknowledges that there is little chance of any significant characteristic ‘fishy’ smell. increase in catches beyond these levels anyway. Antioxidants help slow this decaying process by acting The levelling off of wild catches coupled with the growing as a fall guy for the fatty acid; they take the oxygen hit world population and increasing demand for fish spells and save the fat from oxidative damage. Plant sources of trouble says the FAO. It estimates that an additional 40
28 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils million tonnes of aquatic food will be required by 2030 just ■ Cut down on cholesterol (avoid eggs, meat and to maintain current levels of consumption. This is clearly dairy products) unsustainable, we have to look to alternatives, and fish farming is not the answer. The environmental problems such ■ Avoid or cut down on processed foods, trans fats from as the spread of disease, sea lice and pollution associated margarines and hydrogenated vegetable oils with farmed fish are abundant. The sensible, and in fact the only answer is to obtain our omega-3 fats from sustainable ■ Avoid or reduce fried foods, alcohol, caffeine, sugar, plant sources. smoking and stress For more information on the environmental impact of fishing see Viva!’s guide The End of the Line. Conclusion No short cuts, no magic bullet... Recommendations Fish is not a health food. Neither is it a magical wonder food that can guarantee good heart health and turn all kids into A well-balanced plant-based diet containing green leafy geniuses. The real problem here is not just the lack of good vegetables, wholegrain foods, pulses, nuts and seeds will fats in the diet; it’s the generally appalling state of most ensure an adequate intake of the plant omega-3 ALA. people’s diets. Fish is not a popular food; on average people One of the best sources is flaxseed oil, containing 57 per in the UK eat only a third of a portion of oily fish per week cent ALA and 16 per cent LA with a omega-6:omega-3 with seven out of ten people consuming none whatsoever. ratio of 0.28:1 (Davis and Kris-Etherton, 2003). A 14 gram We should stop looking for a ‘quick miracle fix’ and focus on tablespoonful of flaxseed oil provides eight grams of ALA. the bigger picture… improving our diets by cutting out the Flaxseed oil must be kept in the fridge and added to sauces saturated fatty foods laden with animal fats, sugar, salt and and dips or cooked food. Cooking with it will destroy its cholesterol and eating more fruit, vegetables, pulses, whole beneficial properties. In addition to this, try to buy and store grains, nuts and seeds. nuts, seeds and their oils in small quantities to ensure that they are as fresh as possible and limit the amount of time This report explains what the current research shows: fish the oils have to degrade. may be a source of protective fats but they are not the only, nor the healthiest, source. Fish are also a source of unhealthy It is difficult to say exactly how much of a certain food and unnecessary saturated fat in the diet. Plant-derived should be consumed to optimise EFA intake as the fatty EFAs are a far superior source of good fats in the diet. acid content of foods varies. However, a sensible approach is to reduce consumption of omega-6 rich vegetable oils Environmental contamination of the oceans now means (substitute sunflower or corn oil for olive oil in cooking), that when you take a mouthful of fish you are also taking a while increasing omega-3 intake (found in flaxseed oil, mouthful of neurotoxins and carcinogens (mercury, PCBs walnuts and green leafy vegetables). Limiting or avoiding and dioxins). Some people might consider this game of commercial oil-based processed foods will also help Russian roulette worth the risk if the health benefits afforded improve the omega-6:omega-3 ratio. Consumption of from fish could not be gained elsewhere. However, the saturated fatty acids (and trans fatty acids in processed research clearly shows that ALA from plants can protect foods) should also be limited as they are unnecessary in the heart health and doesn’t come laced with poison. Plant- diet, are a risk factor for atherosclerosis and can interfere derived EFAs have numerous advantages over fish-derived with the conversion of ALA into the longer chain omega-3s. fats yet are virtually ignored by health professionals. This may be due to the paucity of relevant research. The VVF is ■ To improve the conversion of ALA to EPA and DHA trying to address this by pushing for more research including follow these simple guidelines: plant-derived ALA alongside the fish oils EPA and/or DHA. ■ Consume a wide range of wholefoods everyday – Including fish in the typical Western diet, high in saturated remember variety is the spice of life! and processed fat, will not provide the health benefits that many people seek. A far more effective way to achieve good ■ Obtain most fat from whole foods (nuts, seeds, health is to adopt a more plant-based diet low in saturated wholegrains, olives, avocados and soya) fat and cholesterol but containing a healthy amount of polyunsaturated EFAs. Well-balanced vegetarian and ■ Select monounsaturated fat (olive oil) for cooking vegan diets, containing EFA-rich foods, not only help combat heart disease but also protect against many other ■ Use omega-6 fats (sunflower oil, safflower oil) with degenerative diseases. moderation Although the main focus of this report is human health, ■ Use omega-3 fat (flaxseed oil) for salad dressing and in the environmental argument for switching to plant-based dips but do not cook with it (store it in the fridge) omega-3s cannot be ignored. We know how commercial
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About the Vegetarian & Vegan Foundation The Vegetarian & Vegan Foundation (VVF) is a science-based health and nutrition charity which monitors and interprets the growing body of research linking diet and health. The VVF helps the public, health professionals and the food industry make informed choices about diet by providing accurate information and advice about healthy eating. The VVF also runs health and education campaigns, presents school talks, cookery demonstrations, produces a magazine, VeggieHealth, and a wide variety of materials, runs the Vegetarian Recipe Club and answers nutritional queries from the public. The majority of diseases that kill most of us prematurely can be prevented by consuming a plant-based diet – the VVF explains why and provides information and advice about healthy eating. ISBN: 978-0-9557653-4-6

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Fish Report

  • 1.
    THE fish report Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils A scientific report by Dr Justine Butler, Senior Health Campaigner Vegetarian & Vegan Foundation, Top Suite, 8 York Court, Wilder Street, Bristol BS2 8QH. Tel: 0117 970 5190 www.vegetarian.org.uk
  • 2.
    2 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils By: Dr Justine Butler, Senior Health Campaigner, Vegetarian & Vegan Foundation (VVF) Find more information at www.vegetarian.org.uk/campaigns/fish Published by: Vegetarian & Vegan Foundation, Top Suite, 8 York Court, Wilder Street, Bristol BS2 8QH T: 0117 970 5190 E: [email protected] W: www.vegetarian.org.uk © The Vegetarian & Vegan Foundation 2009. Registered charity 1037486
  • 3.
    3 Contents 4 Introduction 22 Contaminated fish are a danger to health 22 POP goes the seawall 5 An introduction to fat 22 PCBs 5 Why do we need fat? 23 Dioxins 5 The chemical structure of fat 23 Mercury rising 7 Getting to know the EFAs 24 Food Poisoning 7 How much fat? 24 Fish and PhIPs 8 Oily fish 25 Farmed and dangerous 8 How much oily fish? 8 EFA deficiency 26 Fish oil supplements 9 Balancing the fat 9 Optimising conversion 26 The official position – not budging 11 Omega-3s from algae – cut out the middleman 27 Plant EFAs leading the way to good health 11 Oily fish, EFAs and health 11 Heart health 27 Sustainability 14 Inflammatory diseases 15 Arthritis 28 Recommendations 17 Multiple sclerosis 19 Allergies 28 Conclusion 20 Brain food 21 Fish oils for brainy kids? 29 References
  • 4.
    4 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils Introduction However, it also continues to recommend we eat oily fish. The mixed messages have left people understandably Over the last decade or so, the reputation of fish oils has confused. undergone a meteoric rise from the dreaded cod liver oil of years gone by to the highly esteemed omega-3 fish oil Farmed fish are not the answer. In general they tend to capsules of the new millennia. If you want to keep up with contain less omega-3s than their wild counterparts and modern nutrition you must be omega-3 savvy! more toxins. In fact, the levels of toxins in farmed fish are a significant concern to many scientists. A comparison of The alternative view is that the only thing ‘clever’ about fish farmed salmon and wild salmon found that the farmed fish oils is the huge marketing campaign that has got thousands had consistently higher levels of contaminants, including of people running to the health food shops. Fish oils are PCBs. Other studies show similar findings. This could promoted everywhere you look – well-known scientists mean considerable health risks for those who regularly recommend them for children, TV adverts hint at their eat farmed salmon. brain-boosting benefits, food producers slip them into all manner of foods. Health food shops struggle to meet Fish is not a popular food in the UK; people eat only a third demand. So convincing is the marketing that many people of a portion of oily fish a week with seven out of ten people believe that oily fish are the only source of the magical consuming none at all. Promoting oily fish as a public health omega-3 fatty acids which keep our hearts healthy, children policy is clearly not working. The worst consequence of this clever and ward off allergies and inflammatory conditions is that more helpful advice on how to get omega-3s from such as arthritis. plant-based foods is just not being given. We’re told that oily fish benefit heart health because of The good news is you don’t have to eat neurotoxins and the omega-3 fats they contain. However, the evidence carcinogens to get your omega-3s; there are perfectly safe is inconclusive. One long-term study showed that men plant sources. Many studies show that omega-3s from plants with heart disease, advised to eat oily fish or fish oil can protect health without exposing us to these harmful supplements, had a higher risk of sudden death from heart toxins. So as part of a vegetarian or vegan diet, plant-based failure than men not so advised. Another study found fish omega-3s provide better protection from heart disease oil supplements increased life-threatening abnormal heart and many other degenerative conditions. This benefits the rhythms in patients with implanted defibrillators. environment as well; plant-based sources of omega-3s are sustainable, fish are not. A review of studies on fish oils and heart health (which included over half a million heart disease patients), showed Safer, healthier and sustainable sources of omega-3s include no clear benefit of omega-3 fats on heart health. One flaxseeds (linseeds), rapeseeds, soya, walnuts and oils made possible explanation the authors suggest for this is the from them. Some species of algae (and supplements made harmful effects of toxins found in oily fish. Many people from them) can provide the longer chain omega-3s found are unaware that all the world’s oceans and rivers are in oily fish without exposing you to harmful pollutants. By contaminated with toxic pollutants such as polychlorinated avoiding fish you can protect your health and help stop the biphenyls (PCBs), dioxins and mercury. These toxins destruction of the oceans caused by over-fishing. accumulate, especially in fatty fish, as you move up the food chain and may completely cancel out any beneficial effects the omega-3s offer. So you are better off getting The research clearly shows that fish oils are not the wonder your omega-3s from healthy plant-based sources such as food the industry would have you believe. They don’t flaxseed oil, hempseed oil and walnuts. These foods are not guarantee good heart health and turn all kids into geniuses. laced with toxic pollutants. They are not the answer to arthritis and other inflammatory conditions (which vegetarians suffer much less from). We This is why the Government has issued warnings to young must stop looking for a ‘quick fix’ and focus on the bigger people, pregnant and breast-feeding women, and those picture… improving our diets by cutting out the foods laden who may become pregnant one day, to limit how much oily with animal fats, sugar, salt and cholesterol and eating more fish they eat. Some governments warn that pregnant and fruit, vegetables, pulses, wholegrains, nuts and seeds. breastfeeding women and children under 16 should not eat larger, older fish such as shark, marlin or swordfish because This fully-referenced scientific report examines the science of the high levels of mercury present. Others have voiced behind the health claims and reveals the research the fish concerns about the levels of dioxins in herring, salmon and industry would rather ignore. It describes why omega-3 mackerel, but most people know little about these risks. fatty acids are important and explains why plant-based These pollutants can harm children and adults as well as oils are better for human health and the environment. It unborn babies and infants. also describes what toxic substances are found in fish and reveals how harmful they can be. It explains why public More recently the Government has extended its warnings health policies promoting oily fish are misplaced and on dioxins and PCBs to include some non-oily fish including: undermine more effective and sustainable strategies. It will sea bream, turbot, halibut, dog fish or huss, and sea bass. leave you in no doubt – fish is not a health food.
  • 5.
    5 An introduction tofat The links between the carbon atoms are called bonds and can be single or double. Saturated fatty acids have Why do we need fat? no double bonds and are fully ‘saturated’ with hydrogen Most people regard all dietary fat as ‘bad’ or unhealthy atoms. Monounsaturated fats have one double bond and but the body actually needs a moderate amount of fat polyunsaturated fats have more than one. The way different (or fatty acids) to function properly. Besides being an fatty acids behave in the body is largely determined by the energy source, fatty acids play a crucial structural role in number and location of these double bonds. all cell membranes; they help hold our cells together. They also help our bodies transport, break down and excrete Saturated fat cholesterol. They are used to make important hormone- As stated, saturated fats have the maximum number of like compounds called eicosanoids which regulate many hydrogen atoms attached to the carbon atoms. This makes processes in the body including inflammation and blood the molecule less flexible. So these fats tend to be solid at clotting. Fatty acids help maintain healthy hair and skin, room temperature, such as lard and butter. they protect vital organs and keep the body insulated. They are also needed to transport the fat-soluble vitamins A, D, E Unsaturated fat and K, from food into the body. In summary, without some Unsaturated (monounsaturated and polyunsaturated) fats fats in the diet, we cannot function. tend to be liquid at room temperature, such as olive and sunflower oil. It is their flexible nature that makes these fats The chemical structure of fat so biologically useful. Figure 1 shows how fatty acids are made up of chains of Figure 2. Cis and trans fatty acids configuration carbon atoms (the carbon backbone) that have hydrogen atoms attached to them. They are referred to as saturated, monounsaturated or polyunsaturated depending on the number of hydrogen atoms attached to the carbon backbone. cis Figure 1. Saturated, monounsaturated and Saturated trans polyunsaturated fatty acids Cis and trans fats The usual shape of naturally occurring unsaturated fats is referred to as ‘cis’ (Latin for ‘on the same side’), as the hydrogen atoms face the same direction (see Figure 2). When the hydrogen atoms are oriented in opposing Saturated fatty acid molecule directions, the molecule is called a ‘trans’ fatty acid (trans means ‘across’ in Latin). Most trans fats are made industrially by adding hydrogen to unsaturated plant oils, in a process called hydrogenation. This process reshapes the double bonds, twisting them so that the hydrogen atoms end up on different sides of the chain. While trans fats are made of exactly the same building Monounsaturated fatty acid molecule blocks as non-trans fats, their different arrangement affects the physical properties of the fat. They are harder, have a higher melting point, and crucially, a longer shelf-life than their cis-shaped equivalents. There is increasing evidence that trans fats are harmful to health. While both saturated and trans fats increase levels of LDL cholesterol (so-called ‘bad’ cholesterol), trans fats also Polyunsaturated fatty acid molecule lower levels of HDL cholesterol (‘good’ cholesterol), thus increasing the risk of heart disease. Indeed, some evidence suggests that trans fats may be even more harmful to health than saturated fats. This position is supported by a scientific Single bond Hydrogen review published in the New England Journal of Medicine Double bond Carbon in 2006 which states that the consumption of trans fatty acids results in considerable potential harm but no apparent benefit (Mozaffarian et al., 2006). Many health authorities worldwide agree and recommend that consumption of trans fat be reduced or avoided altogether.
  • 6.
    6 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils God fat, bad fat We need a moderate amount of so-called ‘good’ fats in the Table 1: Nutritional content of selected oily fish and vegetarian alternatives diet. However, not all fats are created equal. As stated, some 100 grams of: Protein Fat Saturated fat Cholesterol Fibre Energy are beneficial, while others can (grams) (grams) (grams) (milligrams) (grams) (kcal) be harmful. For example, as 60 per cent of the brain is made of fat, it is very important that it is Grilled salmon 24.2 13.1 2.5 60 0 215 provided with enough ‘bendy’ polyunsaturated fatty acids to Smoked mackerel 18.9 30.9 6.3 105 0 354 stay supple and elastic in order to be able to respond to different Tinned sardines 23.3 14.1 2.9 65 0 220 stimuli such as hormones. If the cell membranes in the brain (and other parts of the body) are Smoked tofu 10.9 7.1 1.5 0 0.5 112 rigid they cannot react so well (Saldeen and Saldeen, 2006). This Red lentils, boiled 7.6 0.4 Trace amounts 0 1.9 100 means that less flexible (more saturated) fats may take their Kidney beans, boiled 8.4 0.5 0.1 0 6.7 103 place and normal functioning can be impaired. Tinned chick peas 10.3 2.5 0.2 0 4.3 119 Coldwater fish (salmon, mackerel, sardines and herring) need a high Vegetarian style fish 13.3 15.2 1.9 0 1.0 279 level of flexible polyunsaturated fingers (Redwoods) fats in their cell membranes to enable them to see and swim in cold, dark, watery environments. Sources: Food Standards Agency, Sainsbury’s, Redwoods and Cauldron Foods Just imagine replacing these flexible fats with those from a cold pat of butter (saturated fat), it would not work! Fish 280 milligrams per 100 grams; nearly four times as much obtain their polyunsaturated fats from plankton, algae as is found in a rump steak (FSA, 2002). Whichever way it is and other fish. These fats are also found in eggs and dairy dressed up, fish is not a low-fat food and the high levels of foods (which also contain unhealthy saturated fats) and are cholesterol and saturated fat found in some fish foods make plentiful in plant foods such as nuts and seeds and their them an unhealthy option. oils, avocados and soya foods. Green leafy vegetables contain them too, but not much as they are a very low-fat It could be argued that diets containing oily fish are food. Although olive oil contains some saturated fat, it is associated with a lower risk of heart disease and stroke mainly made up of monounsaturated fat, which is a good compared to diets rich in red meat and dairy foods. substitute for butter, lard or omega-6 fats, such as sunflower However, a vegetarian or vegan diet is the healthiest option. oil, in cooking. Dr Neal Barnard, president and founder of the Physicians Committee for Responsible Medicine in Washington DC, While unsaturated fats are an important part of our diets, says that fish are not low enough in fat or cholesterol to we have absolutely no dietary requirement at all for achieve what vegetarian diets can in terms of promoting saturated fat. Found widely in meat, dairy, eggs, poultry, health. He points out that although the fat content of fish processed foods and fish, this unhealthy type of fat varies widely, all fish contain cholesterol and more fat than contributes to the risk of heart disease and stroke by raising is generally found in the foods that make up a well- blood cholesterol levels. balanced plant-based diet (wholegrains, pulses, fruit and vegetables) most of which contain well under 10 per cent Despite its reputation for containing unsaturated ‘healthy’ fat (Barnard, 2003). fats, much of the fat found in oily fish is saturated (see Table 1). For example, nearly 80 per cent of the calories in smoked In summary, plant-based diets inevitably contain mackerel come from fat and over half of the calories in considerably lower amounts of saturated fat (and either grilled salmon come from fat. Around one-fifth of the total less or no cholesterol) compared to typical Western fat in both these types of fish is saturated (FSA, 2002). diets. Research shows that vegetarians consume a third less saturated fat and only half as much cholesterol as Fish and shellfish are also significant sources of cholesterol; omnivores. Vegans consume even less: half the amount of some species containing nearly as much as steak. The saturated fat eaten by omnivores and no cholesterol (Davis amount of cholesterol in prawns is estimated to be around and Kris-Etherton, 2003). This contributes significantly to
  • 7.
    7 their lower riskof heart disease, stroke and many other docosahexaenoic acid (DHA). LA is an omega-6 fatty acid diseases. (as the first double bond occurs at the sixth carbon atom). Similarly, our tissues can convert it into other longer chain Getting to know the EFAs omega-6 fatty acids, such as gamma-linolenic acid (GLA) In the late 1920s the scientists George and Mildred Burr first and arachidonic acid (AA). introduced the idea that specific components of fat could be necessary for normal growth and development (Burr and Although AA, GLA, DHA and EPA are physiologically Burr, 1929). Since then two specific polyunsaturated fatty important, they are not referred to as ‘essential’ as they can acids have been classified as ‘essential’ as they cannot be be produced in the body from LA and ALA. The essentiality manufactured within the body; they must be provided in of ALA and LA in humans is best explained by our inability the diet. Hence, they are called ‘essential fatty acids’ (EFAs). to introduce double bonds in positions before carbon The two EFAs required for good health are the omega-3 nine (Uauy et al., 2003). In other words, they are classed as fatty acid alpha linolenic acid (ALA) and the omega-6 fatty essential as we can’t make these fats in our bodies. acid linoleic acid (LA). EFAs are important for the normal functioning of all tissues of the body. Figure 3: The fatty acid family They are necessary for the formation of healthy cell membranes, the proper Fats and fatty acids development and functioning of the brain and nervous system and for the production of eicosanoids, important Saturated fats regulators of vital body functions such Unsaturated fats Animal fats, butter, lard as blood pressure, blood-clotting, and immune and inflammatory responses. Polyunsaturated fats Monounsaturated fats How much fat? The UK Dietary Reference Values for the total amount of fat and different Omega-3 fatty acids Omega-6 fatty acids Omega-9 fatty acids fatty acids in the diet were published Alpha linolenic acid (ALA) Linoleic acid (LA) Oleic acid in 1991 (Department of Health, 1991). Eicosapentaenoic acid (EPA) Gamma linolenic acid (GLA) Additional recommendations were Docosahexaenoic acid (DHA) Arachidonic acid (AA) made for omega-6 and omega-3s by the Committee on Medical Aspects of Food (COMA) in 1994 in a review on the ALA is described as an omega-3 fatty acid because the nutritional aspects of CVD (COMA, 1994). first double bond occurs at the third carbon atom along the carbon backbone of the molecule. As shown in Figure Taken together, current UK recommendations are that total 3, ALA can be converted in the body into the longer-chain fat intake should contribute no more than 33 per cent of omega-3 fatty acids eicosapentaenoic acid (EPA) and daily total energy intake and that saturated fats should contribute an average of no more than 11 per cent of food energy, monounsaturated fats an average Table 2: WHO recommendations for daily fat intake of 13 per cent, polyunsaturated fats 6.5 per cent and trans fats no Type of fat Percentage Grams required for women Grams required for men more than two per cent. COMA of total energy (19-50) consuming (19-50) consuming recommended that among the 1,940 calories/day (kcal) 2,550 calories/day (kcal) general population there should be no further increase in average intakes of omega-6 fats but that Total fat 15-30 32.3-64.7 42.5-85.0 intakes of long-chain omega-3 (EPA and DHA) fats should Saturated fat Less than 10 Less than 21.6 Less than 28.3 increase from about 0.1 grams to 0.2 grams per day (COMA, 1994). Polyunsaturated fats 6-10 13.0-21.6 13.3-28.3 These recommendations are Omega-6 5-8 10.8-17.2 14.2-22.7 similar to those given by the World Health Organisation Omega-3 1-2 2.2-4.3 2.8-5.7 (WHO) and Food and Agriculture Organisation (FAO). These are summarised along with the Source: WHO/FAO, 2003.
  • 8.
    8 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils actual amounts of each type of fat required to meet these recommendations in Table 2. Table 3. Oily and non-oily (white) fish In summary, total fat intake should contribute between 15-30 per cent of total energy intake with less than 10 per Oily Fish Non-oily fish cent from saturated fat. Those obtaining more than 10 per cent of their dietary energy from omega-6 fats should not increase their intake of this fat. Most people need to Salmon Cod increase their intake of omega-3s to provide two per cent Trout Haddock of dietary energy. Less than one per cent of calories (but Mackerel Plaice preferably none), should come from trans fats. Herring Coley Sardines Whiting Pilchards Lemon sole Oily fish Kipper Skate Eel Halibut Oily fish have fats throughout their whole body rather than Whitebait Rock salmon/Dogfish only in the liver like non-oily (white) fish. Oily fish fillets may Tuna (fresh only) Ayr contain up to 30 per cent fat, although this figure varies both Anchovies Catfish within and between species. See Table 3 for a list of oily and Swordfish Dover sole non-oily fish. Bloater Flounder How much oily fish? Cacha Flying fish In 2004, in response to a specially commissioned report Carp Hake on the benefits and risks of oily fish consumption, the Hilsa Hoki Food Standards Agency (FSA) issued guidelines on oily Jack fish John Dory fish intake. Table 4 shows the recommended weekly limits. Katla Kalabasu They suggest a limit on the maximum number of portions Orange roughy Ling of oily fish different groups can safely consume each week Pangas Monkfish (a portion is about 140 grams). However, the FSA says that health benefits are greater than the risks as long as you Sprats Parrot fish don’t eat more than the recommended maximums. Hardly Pollack reassuring! Pomfret Red and grey mullet EFA deficiency Red fish For EFA deficiency to develop, dietary intake must be Red snapper extremely low as even small amounts of EFAs can prevent Rohu deficiency. The 2003 National Diet and Nutrition Survey showed that the average daily total fat intakes were close Sea bass to UK recommendations (FSA, 2003). In fact, most adult Sea bream Western diets provide 8-15 grams of EFAs per day and Shark healthy people have a body reserve of 500-1000 grams in Tilapia adipose tissue (Department of Health, 1991). EFA deficiency Turbot in adults is only seen when they make up less than 1-2 per Tinned tuna cent of total dietary energy (Department of Health, 1991). Where EFA deficiency does occur, it is most often seen in Marlin infants fed very poor diets. Table 4: Food Standards Agency recommendations for the Typical symptoms of EFA deficiency include excessive thirst, maximum number of portions of oily fish we should be eating frequent urination, dry or rough skin, dry hair, dandruff, each week (a portion is about 140g) brittle nails, headaches, stomach ache, diarrhoea and constipation (Stevens et al., 1995). Low omega-3 fatty acid Two portions of oily fish Four portions of oily fish status is also associated with behavioural problems such as hyperactivity-impulsivity, anxiety, temper tantrums, sleep Girls and women who might Other women problems and learning difficulties in some children (Stevens have a baby one day et al., 1996). More specifically, low levels of DHA have been associated with several neurological and behavioural Women who are pregnant or breastfeeding Men and boys disorders such as depression, schizophrenia, Alzheimer’s disease and attention deficit hyperactivity disorder (ADHD) (Davis and Kris-Etherton, 2003). Source: FSA, 2009.
  • 9.
    9 fatty acids consumed (Lands, 1992). This is because omega-6 Table 5: Plant sources of EFAs fats compete with omega-3s for use within the body. So excessive 100 grams of: Omega-3 ALA (grams) Omega-6 grams LA (grams) intakes of omega-6 fats can cancel out the positive effects of omega-3s and lead to health Oils problems. Flaxseed (linseed) oil 53.30 12.70 Hempseed oil* 20.00 60.00 Recent changes in the diet have Walnut oil 10.40 52.90 Rapeseed (canola) oil 9.13 18.64 led to a massive rise in our intake Wheatgerm oil 6.90 54.80 of omega-6 fats from plant-based Soya oil 6.79 50.42 oils (such as sunflower oil) and Corn oil 1.16 53.23 most processed foods. This has Sunflower oil 0.00 65.70 increased the ratio of omega-6 to Nuts and seeds omega-3 fats in our diets. Flaxseeds (linseeds) ground, 2 tbsp 22.81 5.90 Walnuts 9.08 38.09 Typical Western diets may Hempseeds* 7.50 22.50 provide ratios of up to 30:1, Vegetables, Fruits and Pulses dramatically skewed toward Soya beans, cooked 0.60 4.47 omega-6 fats. The health Tofu, firm 0.58 4.34 consequences of this could be Broccoli (cooked) 0.11 0.05 far-reaching. Dr. Hibbeln, lead Soya milk 0.08 0.59 clinical investigator on nutrition Strawberries 0.07 0.09 in psychiatry at the National Peas (frozen and cooked) 0.02 0.08 Institutes of Health in Bethesda, Maryland suggests that these major changes in the essential Source: USDA National Nutrient Database for Standard Reference, 2008. * Adapted from Leizer et al., 2000, fatty acid composition of the Journal of Nutraceuticals, Functional and Medical Foods. 2 (4) 35-53. food supply may be linked to a range of psychiatric disorders and may even contribute towards These findings are consistent with evidence that omega-3 fatty an increased risk of homicide, suicide and social instability acids are important for brain function and that low omega-3 (Hibbeln, 2007). intake may have negative effects on behaviour, learning and mood. It is important then to make sure that there are adequate The WHO/FAO joint recommendation is a ratio of LA to ALA levels of these important nutrients by supplying sufficient of 5:1-10:1 (WHO/FAO, 1994). Other recommended ratios vary ‘parent’ fatty acids for conversion. Most people can obtain all but a cautious approach would be to aim for a ratio between the EFAs they require from a well-balanced plant-based diet 2:1 and 4:1 making sure not to exceed 6:1 (Davis and Kris- including flaxseed oil, nuts and seeds as well as plenty of green Etherton, 2003). This ratio can be achieved by reducing the leafy vegetables. In most cases, dietary replenishment of EFAs use of sunflower, safflower and corn oils and increasing the will usually reverse any deficiency. use of ALA-containing oils such as flaxseed, rapeseed and soya bean oils. Of course, optimising omega-3 conversion Table 5 shows which plant-based foods can be used to boost rates can help improve your omega-6:omega-3 ratio too. your intake of omega-3 fats. Note that the fats and oils are easily damaged by light or heat so are best kept refrigerated. Optimising conversion Furthermore, these oils should not be used in cooking; use The body converts ALA into the longer chain omega-3s them on salads, in dressings and dips. (EPA and DHA), otherwise found in fish and some species of algae. However, we are repeatedly told (particularly by fish People with diarrhoea, irritable bowel syndrome, diverticulitis oil supplement companies) that conversion rates are low and or inflammatory bowel disease (Crohn’s disease or ulcerative inefficient. The claim that we cannot convert enough ALA to colitis) should use caution if taking flaxseed (but not flaxseed EPA and DHA is simply not true, but does serve to protect oil) due to its possible laxative effects. If you have a medical the fish oil market. The better health statistics for vegetarians condition, or are taking other drugs or supplements you and vegans – who don’t eat fish – provides proof that they should consult a doctor or nutritional therapist before don’t go short. changing your diet. Several studies have measured the rate at which we convert Balancing the fat ALA to EPA and DHA. A conservative estimate is that about Research suggests that the ratio of omega-6 to omega-3 5-10 per cent of ALA is converted to EPA, and 2-5 per cent fatty may be more important than the amounts of individual to DHA (Davis and Kris-Etherton, 2003). However, as the
  • 10.
    10 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils body’s fat deposits usually contain ALA, even a very low and DHA and depletes tissues of these long chain omega-3 conversion rate of just 2.7 per cent, would allow an average fatty acids (Davis and Kris-Etherton, 2003). person to make the same amount of EPA as would be found in 18 large (1,000mg) capsules of the omega-3 richest fish oil Consuming excessive amounts of omega-6 fatty acids (Erasmus, 1993). Even a person with no omega-3 fats in their (associated with some vegetable oils, particularly safflower, body, (perhaps after a long-term dietary shortfall) who takes sunflower and corn oils) can have a detrimental effect on two tablespoons of flaxseed oil a day, can produce more conversion rates too (Uauy and Castillo, 2003). Indeed, a EPA than contained in two large fish oil capsules. high omega-6 intake may reduce omega-3 conversion by as much as 40 per cent (Davis and Kris-Etherton, 2003). Other studies show much higher levels of conversion. There is no need to avoid or cut down on omega-6-rich Research from the Institute of Human Nutrition at the wholefoods (sunflower seeds, pumpkin seeds, sesame University of Southampton found ALA conversion rates in seeds, wheat germ and soya foods) as they contribute much young women of 21 and nine per cent for EPA and DHA less to overall omega-6 intake and contain an abundance of respectively (Burdge and Wooton, 2003). other healthy nutrients. Furthermore, a recent study from the University of Davis and Kris-Etherton recommend that the primary Cambridge revealed that vegetarians convert more ALA fat in the diet should come from foods and oils rich in to EPA and DHA than fish-eaters (Welch et al., 2008). In monounsaturated fat, as when monounsaturated fats this study, the ratio of circulating EPA and DHA to dietary predominate, saturated fats, trans fats and omega-6 intake of ALA was used as an indicator of conversion rate; fats are kept in check (Davis and Kris-Etherington, 2003). the higher the ratio, the greater the conversion rate. Results Monounsaturated fats are found in nuts, peanuts, olives and showed the ratio was 22 per cent higher in vegetarians than olive oil, avocados and rapeseed oil. As stated, wholefoods fish-eaters, indicating a higher conversion rate. This may are superior source of fats as they contribute many other explain why fish-eaters and non fish-eaters have a smaller nutrients to the diet. than expected difference in circulating omega-3 levels. Lastly, it is important to optimise the intake of ALA for Taken together, the research indicates that we can convert conversion into EPA and DHA. As stated above, ALA should as much or as little as we need, providing we have enough provide 1-2 per cent of total energy intake in the diet. Good starting material (ALA). sources include ground flaxseeds and their oil, hempseed, rapeseed, walnuts, soya beans and products made from In addition to this, we are capable of ‘retroconversion’, them, green leafy vegetables and some species of algae which means we can make EPA from DHA. Research from (which contain DHA). Table 6 shows the amount of omega- the Department of Nutritional Sciences at Pennsylvania 3-rich food you can take to achieve the recommended daily State University states that up to 10-11 per cent of DHA is intake (along with a well-balanced plant-based diet). retroconverted to EPA. The authors of this study conclude that if sufficient ALA and DHA are consumed, total EPA If more people knew that they could produce sufficient production would be expected to be adequate (Davis and amounts of EPA and DHA from ALA they might be less Kris-Etherton, 2003). inclined to turn to potentially decaying and contaminated So if you take an algal supplement that contains DHA you can boost both DHA and EPA levels without exposing yourself to toxic pollutants found in fish oils. Furthermore, Table 6: suggested daily intake of foods rich in omega 3 the EPA we make in our bodies has the advantage of being fresher and more stable than that found in fish oils. Source One of the following A range of dietary factors can affect efficiency of conversion too. Poorly designed diets are thought to reduce the rate of Flaxseed (linseed) oil 1-2 tsp conversion as both energy and protein are needed to drive the enzymes that convert EFAs. In addition, a wide range Ground flaxseed (linseed) 2 tbsp of nutrients are required to optimise conversion including biotin, calcium, copper, magnesium, niacin (vitamin B3), pyridoxine (vitamin B6), vitamin C and zinc (McKevith, 2005; Rapeseed oil 2 tbsp Siguel and Lerman, 1994; Horrobin, 1992). A well-balanced plant-based diet will provide all these nutrients and more. Hempseed oil 1 tbsp Excessive intakes of trans fatty acids can limit conversion rates. These unhealthy fats, found in hydrogenated fat in Hempseed 3-5 tbsp margarine and products made with it (such as biscuits and pastries), are also found in meat and dairy products. Alcohol Walnuts 8 halves (28 grams) inhibits activity of the enzymes that convert ALA into EPA
  • 11.
    11 fish oils. Theresearch indicates that the only thing Reinfarcation Trial (DART) (Burr et al., 1989). This study vegetarians and vegans miss out on by avoiding fish is the looked at the effects of dietary intervention in the toxic pollutants that contaminate them. secondary prevention of heart attacks in patients who had previously recovered from one. In this study 2,033 men who Omega-3s from algae – cut out the middleman had recovered from a heart attack were allocated to receive Whilst omega-3 is present in fish oil, fish do not produce or not receive advice to eat around 300 grams of oily fish omega-3 in their bodies. Fish obtain their omega-3 from per week, or take fish oil supplements giving an equivalent their diet of algae. People who are concerned about intake amount of omega-3 fats. of DHA can use algal supplements as a source of this long chain omega-3 too. There are even brands available online Results showed that the fish group had a 29 per cent that can provide both DHA and EPA. reduction in death during the two year recovery period following a heart attack. So it was concluded that fish oil Algae used for omega-3 supplements is usually grown may reduce CVD mortality; the effect being greatest during in controlled conditions away from the sea, so it doesn’t the period of recovery following a heart attack. interfere with the marine ecosystem and doesn’t impact on fish stocks nor their natural food source. So, in addition Burr suggested that omega-3 fats may help normalise to the numerous health benefits of this vegan-friendly heartbeat rhythms by exerting what is called a beneficial source of long chain omega-3s, it is a more environmentally anti-arrhythmic effect. In other words, omega-3s may help friendly choice. your heart beat more regularly and calm irregular activity (arrhythmia). Others agree that the most likely mechanism By switching from fish to a plant-based source of omega-3 by which EPA and DHA reduce the recurrence of heart you’ll be doing yourself a favour and the environment too, disease is by stabilising arrhythmias (Marchiolo et al., whilst getting the safest, toxin-free omega-3 fats. 2002). Research suggests that the anti-arrhythmic effect of omega-3 fats is partly due to their ability to reduce the electrical excitability of cells. Oily fish, EFAs and health As stated, fish oils (or components of them) may also offer benefit by reducing blood-clotting. Platelet cells Heart health found in the blood ensure that blood becomes sticky Why are oily fish promoted as essential for good health? (platelet aggregation or blood-clotting). This is important The answer lies, partly, in the role EFAs may have in for stopping bleeding, for instance, if you are wounded. lowering the risk of heart disease and stroke. However, too much clotting can cause the cells to clump together and stick to the walls of blood vessels. This can Oily fish first got the nutritional thumbs up when it was lead to heart disease and stroke. EPA appears to reduce observed that populations such as the Japanese and Inuit the tendency of blood platelets to clump together. (Eskimo) people, with their fish-rich diets, have much lower Consequently, it may prevent the formation of blood rates of CVD. Further investigation suggested that the EPA clots and the narrowing of coronary arteries, which can and DHA fatty acids found in fish can help reduce blood- lead to a heart attack. However, extensive reduction in clotting, lower blood pressure and cholesterol levels and platelet aggregation can lead to prolonged bleeding times lower triglyceride (fat) levels in the body. All these effects following injury. It is important that blood is neither too can help lower the risk of CVD. However, the promotion thick nor too thin. of oily fish ignores the fact that EPA and DHA can also be formed within the body from plant sources of ALA. Those taking blood-thinning medication (such as daily Not to mention the toxic pollutants found in fish and the aspirin or warfarin), should speak to their GP before eating environmental catastrophe of industrial fishing. lots of food that has added omega-3 or before taking fish oil supplements, as this can also reduce blood-clotting. Numerous studies have looked at the benefits of eating polyunsaturated fatty acids (particularly the omega-3s: ALA, Interestingly, although there were less fatal heart attacks EPA and/or DHA) to reduce the risk of heart disease. Three among the DART fish group, the total number of attacks major studies are frequently referred to: the DART, GISSI was not reduced. So although eating oily fish reduced and LYON studies. The DART and GISSI trials demonstrated the risk of dying after a heart attack, it did not prevent a how fish oils could reduce mortality in people with CVD. secondary heart attack. Whereas a large body of evidence However, there is now a large body of evidence showing shows that plant-based diets can be used to both prevent how plant-based ALA can do the same without exposure to and even reverse heart disease (see the VVF guide Have a harmful toxins found in oily fish. The third well-known study, Heart for further information). the LYON study, clearly demonstrated this. GISSI – using fish oil supplements to prevent DART – using dietary fish to prevent secondary secondary heart disease heart disease The GISSI-Prevenzione trial similarly looked at the effect One of the best-known early studies was the Diet and of EPA and DHA on 11,324 patients (primarily men) who
  • 12.
    12 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils had recently survived a heart attack. Half the participants identical. So the dietary advice given to former DART received a daily supplement (1 gram per day) of omega-3 participants, over a decade previously, offered no long- fish oil capsules, while the other half did not (GISSI, 1999). term protective effect. So while fish oil may offer short-term protection to people who have suffered a heart attack, this After three-and-a-half years, results showed a 20 per cent protection does not appear to stand the test of time. reduction in the overall death rate among the fish oil group. However, like the DART trial, the rate of non-fatal A further study looked at whether dietary advice (to eat oily heart attacks was unchanged. It should also be noted that fish or fish oil supplements) could reduce the death rate the large amount of omega-3 fats given (1 gram) is the among men with angina (Burr et al, 2003). Another surprising equivalent of consuming a very large amount (around 100 result was found: advice to consume fish and the intake of grams) of oily fish per day. This exceeds the ‘safe’ amount fish oil capsules was associated with an increase in mortality the UK government recommends (FSA, 2009). of 20 per cent and 45 per cent respectively! Furthermore, this increase was even more prominent for sudden death. More recently, a Finnish study looking at the relationship Such results should make health organisations and the between omega-3 levels and the five-year risk of heart Government sit up and rethink their position on fish and fish attack and death in patients with heart disease found that oil in the primary and secondary prevention of heart disease. relatively high blood levels of omega-3 fats were associated with a lower risk of death (Erkkilä et al., 2003). However, like More recently, in 2006, a major review published in the British the previous trials, omega-3s did not prevent the recurrence Medical Journal drew the evidence together by reviewing all of a heart attack. This finding fits well with those from the relevant studies published over the previous four years earlier studies showing that fish consumption and omega-3s (Hooper et al., 2006). It looked at 89 studies on omega-3 fats may be associated with decreased death rates but do not and health and concluded that long chain and shorter chain necessarily prevent a secondary heart attack in high-risk omega-3 fats do not have a clear effect on total mortality, subjects. Conversely, there is a huge body of evidence (see combined cardiovascular events or cancer. below) showing how vegetarian or vegan diets can actually reverse heart disease in patients and so reduce both death The review noted that the 2003 study by Burr contradicts the rates and secondary heart attacks. other large studies by not suggesting a benefit of omega- 3s in patients with angina. One possible explanation the No benefit from fish for low-risk heart researchers suggest for this is that as this trial had the longest disease populations follow-up period of all the studies reviewed it could be that While the DART and GISSI trials suggested that fish oils may the negative effects of oily fish and fish oil supplements reduce death rates in people who have already had a heart were due to the cumulative harmful effects of mercury. In attack, the same cannot be said for the wider population. other words, the pollutants in fish and fish oil supplements A major review of studies examining the relationship taken over time may cancel out the beneficial effects of the between fish intake and heart disease found that fish omega-3 fats they contain. consumption is not associated with a reduced risk in low- risk populations (people with no history of heart problems) Another study found fish oil supplements increased life- (Marckmann and Gronbaek, 1999). This review concluded threatening abnormal heart rhythms in patients with that healthy people (at low-risk of heart disease) do not gain any additional protection for the heart from eating fish. implanted defibrillators (Raitt et al., 2005). This study actually The authors question whether the apparent protection in found that fish oil supplementation did not reduce the risk of high-risk individuals is attributable to eating fish or whether abnormal or irregular heart rhythm and may even be pro- the link might be explained by other dietary or non-dietary arrhythmic in some patients. confounding factors. LYON – using plant-derived ALA to prevent In a later editorial, one of the review authors reaffirmed secondary heart disease that while an average daily intake of 50 grams of fish may The Lyon Diet Heart Study investigated whether a lower heart disease death rate, the apparent protection Mediterranean-type diet could reduce secondary heart is limited to high-risk populations (Marckmann, 2003). disease (a second heart attack) compared to a prudent Marckmann observes that both the DART and GISSI trials Western-type diet (de Lorgeril et al., 1999). were well-designed and performed and the results were convincing. However, he says that their conclusion, that heart In this study, 423 patients with a history of heart attack were disease patients should be prescribed oily fish or fish oil randomly assigned either a Mediterranean diet or a prudent supplements, has been seriously challenged by more recent Western diet (as recommended by the American Heart research. Association). The Mediterranean diet was largely plant-based containing more bread, pulses (peas, beans and lentils), No long-term protection against heart disease vegetables (both root and green vegetables) and fruit. Butter A long-term follow-up to the DART study (Ness et al., 2002), and cream were replaced with healthier fats including olive showed that the death rate in the two groups (fish and oil and rapeseed oil margarine. The diet did contain fish, but no fish) after an average follow-up of 15 years was almost less red meat, and overall it was lower in animal fat.
  • 13.
    13 The Mediterranean dietwas significantly lower in cholesterol Evidence suggests that LDL can also harm the walls of and higher in a number of beneficial substances such as ALA. the arteries when it is damaged or oxidised (Galassetti Earlier work with this group revealed a 70 per cent increase and Pontello, 2006). So what has this to with the diet and in circulating levels of ALA and a 40 per cent rise in EPA (de what can be done about it? Well, quite a lot. For example, Lorgeril et al., 1994). Although fish intake was encouraged, one study showed how eating two eggs a day for three the experimental group ate only seven grams a day more fish weeks not only raised LDL levels by about 10 per cent than the control group, leading the researchers to conclude but increased oxidised LDL by 34 per cent (Levy et al., that the favourable EPA level seen in the test group was due 1996). The authors concluded that egg consumption, in to plant-ALA intake rather than the fish in the diet. addition to raising cholesterol, increased how readily LDL could be oxidised. This, in turn, enhanced the progression Results showed a striking drop in death rates (due to a of atherosclerosis (the build up of fatty deposits in the reduction in heart disease) of close to 70 per cent. Compared arteries). It was concluded that this may contribute to the with the DART trial, the protective effect was associated high levels of heart disease seen in populations with high with ALA instead of EPA. Another important difference cholesterol intakes. was that the protection ALA offered extended to non-fatal heart attacks. The authors of this study suggested that The precise mechanism underlying how eggs increase LDL moderate amounts of omega-3 fatty acids (such as in the oxidation is unclear, although their relatively high omega-6 Mediterranean diet), may work in multiple ways to reduce the intake has been blamed (Shapira and Pinchasov, 2008). risk of heart attacks and sudden death. Conversely, a healthier diet, such as the Mediterranean diet (rich in antioxidants and flavanoids), appears to reduce how Just to be clear, the only fatty acid associated with the readily LDL is oxidised (Lapointe et al., 2006). Interestingly reduction in heart attacks was ALA. The authors did not find though, antioxidant supplements and fish oil supplements have not been clearly demonstrated to prevent LDL any correlation between the longer-chain omega-3 fatty oxidation. acids (EPA and DHA) and a reduction in cardiac events. The Lyon Diet Heart Study demonstrated that plant-derived ALA Research shows that LDL in vegetarians is less susceptible is extremely effective in reducing the risks of secondary to oxidative damage (Lu et al., 2000). This may be due to heart disease. It demonstrated that plant ALA was superior the low-fat, high-antioxidant (beta-carotene and vitamins to fish-derived EPA and DHA in reducing the risk of a second C and E) and/or soya food content of a well-balanced heart attack. This study also confirmed that ALA can confer plant-based diet. This could be one of the reasons why the long-term protection to heart health. Mediterranean diet is associated with a lower incidence of heart disease (Lapointe et al., 2006). These and other Three years later, in an article published in the journal studies provide strong evidence that plant-based omega-3s Circulation, Dr J. David Spence of the Stroke Prevention can protect heart health and that contrary to popular belief, and Atherosclerosis Research Centre at Robarts Research oily fish are not the only (nor indeed the best) source of Institute in London, Canada, asked why the Lyon study was these valuable nutrients. so neglected (Spence, 2002). Spence believes this study should have set the benchmark for dietary recommendations. Spence states that it is no longer reasonable for patients He stressed how Mediterranean diets have been shown to with heart disease to be prescribed diets containing improve endothelial function (how the internal lining of the a daily intake of animal flesh (Spence, 2002). Dietary blood vessels work). Spence also attributed the protective recommendations, he suggests, should be based on diets role of this type of diet to the higher levels of antioxidants similar to that used in the Lyon study. they contain. A large body of evidence indicates that antioxidants may be able to reduce atherosclerosis (the Plant omega-3s and heart disease progressive thickening and hardening of arterial walls that Many other studies indicate that plant omega-3s have results from the build up of fatty deposits) (Azen et al., 1996). a protective effect against heart disease. The Health Professionals’ Study looked at 43,757 men over six years Spence also suggested that dietary cholesterol is more (Ascherio et al., 1996). During this time 229 men suffered harmful to health than previously thought. Cholesterol is a a fatal heart attack and 505 a non-fatal heart attack. This fatty substance mainly produced by the liver (in response to study found that a one per cent increase in ALA intake saturated fat intake) but it is also supplied in diets containing lowered the risk of heart attack by 59 per cent. It was animal-based foods (meat and dairy). Plant foods don’t concluded that diets high in ALA from plants are associated contain any cholesterol. It is carried in the bloodstream by with a reduced risk of heart disease. molecules called lipoproteins (a mixture of fat and protein). Low-density lipoprotein (LDL) takes cholesterol from the Similar findings were reported in the Nurses’ Health Study liver to the cells and is often referred to as ‘bad’ cholesterol which looked at over 76,000 women over 10 years (Hu et because when levels are high, it can accumulate on the walls al., 1999). During this time 232 women suffered a fatal heart of the arteries. High-density lipoprotein (HDL) carries excess attack and 597 a non-fatal attack. Those who consumed the cholesterol back to the liver for excretion and is therefore most ALA had a 45 per cent lower risk of fatal heart disease. called ‘good’ cholesterol. The risk was further lowered among women who also took
  • 14.
    14 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils vitamin E supplements or who had a lower intake of trans With declining fish stocks, polluted seas and oceans, fatty acids. The authors concluded that higher consumption the role of plant-based omega-3s in heart disease must of foods such as oil-based salad dressings that provide be further examined. The possibility of a simple and polyunsaturated fats, including ALA, may reduce the risk of sustainable plant-based solution can no longer be ignored. fatal heart disease. Veggie diets and heart disease In the 2001 National Heart, Lung and Blood Institute Family Plant-based diets have been shown to prevent and even Heart Study, the diets of 4,584 participants were assessed reverse heart disease. Dr Dean Ornish, Clinical Professor of (Djousse et al., 2001). Results showed that men who Medicine at the University of California in San Francisco, is consumed the most ALA had a 40 per cent lower risk of heart well-known for his Lifestyle Heart Trial in which he treated disease and women who consumed the most had a whopping severe heart disease patients with lifestyle changes alone 50-70 per cent reduction. (Ornish et al., 1990; Ornish et al., 1998). The experimental group ate a low-fat wholegrain plant-based diet containing In 2003, a joint report by WHO/FAO concurred that ALA has a lots of fruits, vegetables and pulses. They also followed protective effect against heart disease (WHO/FAO, 2003). The an exercise programme, practised various forms of stress report states that several prospective studies have found an management but did not receive medication. They were inverse association between the intake of ALA (from flaxseed, monitored against a control group of similar patients who rapeseed and soya bean oils) and risk of fatal heart disease. In received conventional treatments. other words, ALA protects against death from heart disease. After just one year, 82 per cent of patients on this lifestyle It has been suggested that the protective effects of ALA are change regime had regression of their heart disease with a particularly evident among subjects with low intakes. This 91 per cent reduction in chest pain and reduced cholesterol may be in parts of Europe where sunflower oil is used almost levels. Whereas the control group experienced a 165 per exclusively, or in developing countries where palm oil is used cent increase in the frequency of chest pain, cholesterol (both oils lack ALA). was worse and blockages of their arteries became worse. This trial has continued with similar results and continues to In 2008, a study published in Circulation, the Journal of the achieve better results than conventional surgical or medical American Heart Association, investigated the role of ALA in intervention. heart disease in Costa Rica where ALA intake was low but is increasing due to the switch from palm oil to soya bean oil More recent work shows that vegetarians generally have a (Campos et al., 2008). This study found that a 1.79 gram per much lower risk of heart disease than meat-eaters. A major day intake of ALA (supplying 0.65 per cent of total energy) review of the scientific evidence shows that vegetarians decreased the risk of a second heart attack in heart disease have a massive 25 per cent lower risk of dying from heart patients by 57 per cent, compared to a 1.11 gram per day disease! The authors of this study conclude that the intake (supplying 0.42 per cent of total energy). The authors widespread adoption of a vegetarian diet could prevent suggest that the amount of ALA needed to reduce the risk of approximately 40,000 deaths from heart disease in Britain a second heart attack can be obtained from just 2 teaspoons each year (Key et al., 1999). of soya bean or rapeseed oil, 1-2 millilitres of flaxseed oil or just 6-10 halves of walnuts per day. As stated, meat, poultry, fish, eggs and dairy products all contain cholesterol, while a plant-based diet contains little The Cochrane Collaboration is an international not-for-profit, or no cholesterol. It should be no surprise then that a large- independent organisation, dedicated to making up-to-date, scale study investigating cholesterol levels among vegans, accurate information about the effects of healthcare readily vegetarians, fish- and meat-eaters found that the vegans available worldwide. The Collaboration’s systematic reviews had the lowest levels, vegetarians and fish-eaters had of healthcare studies are published quarterly as part of The similar values and the meat-eaters had the highest (Appleby Cochrane Library. Cochrane reviews have become known et al., 1999). internationally as sources of high quality, reliable health information. For vegans it’s a win-win situation. Not only do they avoid harmful substances (saturated animal fat, animal protein In 2004, the Cochrane Collaboration reviewed the current and cholesterol), they also benefit from a wide range of evidence to see whether dietary or supplemental omega-3 healthy nutrients including fibre, vitamins and minerals. fatty acids alter total mortality (death rate) or cardiovascular events (heart attack and stroke) (Hooper et al., 2004). They Inflammatory diseases concluded that there was no overall benefit either on heart It is reported that omega-3 fats can help fight heart attacks, deaths from heart disease or overall mortality. The disease, asthma, type 1 diabetes and multiple sclerosis. authors concluded that there was not enough evidence to say The beneficial effects have also been seen in some cancers, that people should stop taking rich sources of omega-3 fats, inflammatory bowel disease, arthritis, osteoporosis, mental but said that further high quality trials are needed to confirm health, dry eye disease, age-related macular degeneration the previously suggested protective effect of omega-3 fats for and psoriasis (Simopoulos, 2008). Many of theses conditions those at increased cardiovascular risk. involve inflammation.
  • 15.
    15 Our bodies useinflammation to protect tissues from This chronic condition is characterised by hot painful infection, injury or disease. The inflammatory process swelling in the joints. It usually starts in the wrists, hands usually promotes healing but, when uncontrolled, it can and feet but can spread to other joints in the body. In some also harm. We now know that the balance of omega-6s diseases inflammation can help towards healing, but in to omega-3s is important for regulating inflammation. rheumatoid arthritis it tends to cause damage. For some As a general rule, omega-6 fats are thought to be pro- people the discomfort, pain and loss of mobility caused by inflammatory, whereas omega-3 fats are considered anti- this condition can have a serious impact on their lives. inflammatory (GLA is the exception as it is an omega-6 fat with anti-inflammatory properties). The dramatic Rheumatoid arthritis affects approximately 350,000 people increase in dietary saturated and omega-6 fats, coupled in the UK and like osteoarthritis, is also more common in to the decrease in omega-3 fats is linked to the increasing women than men. It is most common after the age of 40, but incidence of numerous inflammatory diseases including can affect people of any age (NHS Direct, 2008b). asthma, allergy and atherosclerosis (Chilton et al., 2008). Diet and arthritis There is evidence that changing the diet can help some In the past, arthritis patients were told that dietary changes people with inflammatory conditions; some of these are would not help them. Despite this many arthritis patients discussed below. have found that certain foods can worsen their condition, or improve it. Arthritis Arthritis is a painful condition of the joints and bones. Arthritis Care is the UK’s largest voluntary organisation There are many different forms of this condition. The two working with and for people with arthritis. It suggests that a main types are rheumatoid arthritis and osteoarthritis. diet high in fruit, vegetables, pasta, fish and white meat, and low in fatty foods such as red meat, cream and cheese can Other forms of arthritis include ankylosing spondylitis, help (Arthritis Care, 2008). Most people would benefit from cervical spondylitis, fibromyalgia, lupus, gout, psoriatic eating less saturated fat and sugar and eating more complex arthritis and Reiter’s syndrome (NHS Direct, 2008). carbohydrates, fibre, vitamins and minerals. Evidence shows that at least for some people with arthritis, a healthier diet Osteoarthritis can help considerably. Osteoarthritis is the most common type of arthritis in the UK, with an estimated 8.5 million people affected by the In 2001, the first controlled study examining the long-term condition (NHS Direct, 2008a). This degenerative disease is effect of a vegan, gluten-free diet on rheumatoid arthritis sometimes referred to as ‘wear and tear’ arthritis. Cartilage found that this diet could improve the signs and symptoms is the strong, smooth surface that lines the bones and of this condition (Hafström et al., 2001). The authors of allows joints to move against each other easily without this study suggested that a gluten-free vegan diet may, in friction. In osteoarthritis, cartilage gradually breaks down some people, reduce the immune response that triggers faster than it can be repaired. Eventually the surface of the rheumatoid arthritis. Another study tested a low-fat, vegan bones begin to rub together causing them to degenerate. diet in patients with moderate-to-severe rheumatoid arthritis (McDougall et al., 2002). Results also showed those In osteoarthritis, damage to cartilage can result in bony who switched to this type of diet experienced a significant growths developing around the edge of the joints causing reduction in symptoms. mild inflammation of the tissues (synovitis). Osteoarthritis mostly occurs in the knees, hips and small joints of the A further study showed that an uncooked vegan diet, rich hands. However, almost any joint can be affected. in antioxidants and fibre, decreased joint stiffness and pain in patients with rheumatoid arthritis (Hänninen et Osteoarthritis generally occurs in the over 50s and is al., 2000). Some studies have looked at fasting followed more common in women than men. However, it is not an by a vegetarian or vegan diet. A review of these studies inevitable part of getting older. It can develop after an concluded that this dietary treatment might also be injury to a joint; this can happen months or even years after beneficial for people with rheumatoid arthritis (Müller et al., the injury. 2001). Taken together, these studies provide strong evidence that dietary modification can benefit arthritis patients. Studies have been carried out to try to find whether omega-3 fats and/or fish oils can be helpful for Weight control osteoarthritis, but the results so far are inconclusive. It is widely accepted that it is important for people with arthritis to maintain a healthy weight. The extra burden on Rheumatoid arthritis the joints, in overweight or obese arthritis patients, can Rheumatoid (inflammatory) arthritis is a more aggressive, make symptoms considerably worse and losing weight can but less common condition than osteoarthritis. It is thought have a dramatic beneficial effect. to be an autoimmune disease whereby the body’s own immune system attacks the joints, causing pain, swelling The Arthritis Research Campaign (ARC) promotes medical and the destruction of bone and cartilage. research into the cause, treatment and cure of arthritic
  • 16.
    16 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils conditions. ARC’s dietary guidelines for people with arthritis Omega-6 fats do not appear to benefit people with suggest that one of the most important links between diet arthritis. In fact they may increase inflammation by and arthritis is being overweight (ARC, 2006). competing with omega-3s (ARC, 2006). Most people have diets which already contain more omega-6 fats than they Adopting a plant-based based diet can help people lose need. If you have inflammatory arthritis, it may be helpful to weight and maintain a healthy body weight. Numerous replace some of the omega-6 fats (found in sunflower oil, studies show that vegetarians and vegans weigh less corn oil and products made from them such as sunflower than meat-eaters. A study of over 55,000 Swedish women margarines) with omega-3 fats from flaxseed, hempseed revealed that the vegetarian and vegan women were less and rapeseed oils and walnuts. Obtaining plant-based likely to be overweight or obese than the meat-eaters omega-3s from these sources will ensure you get this (Newby et al., 2005). In another study, the effects of a low- healthy fat without exposing your body to the harmful fat, plant-based diet on 64 overweight postmenopausal toxins found in oily fish. women was compared to a diet based on National Cholesterol Education Program guidelines (Barnard et Gout al., 2005). Results showed that the low-fat, vegan diet ARC warns that people with gout should not consume was associated with significant weight loss. A subsequent oily fish. Gout is a type of arthritis caused by a high level review of 40 studies revealed that, on average, vegetarians of urate in the body which can crystallise in the joints and and vegans weigh between six pounds and two stones less cause severe pain and inflammation. Urate is produced from than meat-eaters (Berkow and Bernard, 2006). purines, which are chemicals that result from the natural death of cells. Cutting down on foods which are high in When trying to lose weight, it is important to maintain purines may be helpful if you have gout. This is best done a good intake of nutrients. A healthy balanced diet by replacing animal-based foods (especially meat and fish) with other sources of protein, such as pulses (peas, beans, containing plenty of fruit and vegetables, pulses and and lentils). Other dietary measures for gout include losing wholegrain foods (wholemeal bread, brown rice and weight (if you are overweight) and avoiding excessive alcohol wholemeal pasta) provides a good supply of vitamins, consumption, which has been associated with gout for minerals and fibre. A diet lacking in these foods and rich centuries (ARC, 2006). in meat, dairy and processed foods (such as white bread, white rice and white pasta) does not provide such a good Calcium source of nutrients. Find out how to achieve and maintain a A well-balanced healthy diet can help you if you are taking healthy weight while protecting your health too in the VVF’s strong drugs for arthritis. In fact, ARC states that if you are V-Plan Diet guide. taking strong drugs for arthritis there is even more reason to eat a good diet as it can help to protect the body against Getting the fats right some of the side-effects of the drugs. For example steroids, ARC states that vegetarian diets have been shown to be such as prednisolone, can cause osteoporosis, particularly helpful in the long-term to some people with rheumatoid if you stay on them for a long time. Plenty of calcium in your arthritis. It also says that a vegan diet (no meat, fish or other diet will help to reduce the risk (ARC, 2006). animal products such as eggs, milk, cheese or other dairy products) may also be helpful (ARC, 2006). Conversely, Arthritis Care points out that people with rheumatoid arthritis studies have shown that people who eat large amounts are at increased risk of developing osteoporosis and agrees of red meat seem to have a higher risk of developing that ensuring an adequate calcium intake is very important inflammatory arthritis. (Arthritis Care, 2007). While cow’s milk and dairy products are indeed a source of calcium, they are not the best source. This The key point here is that not only is a plant-based is because they contain animal protein. Excessive amounts diet helpful because it contains beneficial substances of animal protein can upset the acid balance within the (antioxidants and omega-3 fats), but a typical Western diet, body, which then takes calcium from the bones to neutralise rich in meat, dairy and processed foods, is detrimental the acid. Even the usually pro-dairy National Osteoporosis as it contains high levels of harmful substances such as Society says: “It is a good idea to avoid too much protein, saturated fat. This unhealthy type of fat tends to come from particularly animal protein such as meat and cheese,” (NOS, animal-based food (particularly meat, poultry and dairy 2008). It is also a good idea to avoid too much salt, fizzy products) and processed foods (cakes, pastry and biscuits). drinks and caffeine for the same reason. This unhealthy fat is the most important kind to avoid as it can increase pain and inflammation in arthritis (ARC, 2006). Healthier sources of calcium include green leafy vegetables (broccoli, kale, spring greens, cabbage, parsley and Plant-based diets tend to contain considerably less watercress – but not spinach), dried fruits (figs and dates) saturated fat and more healthy polyunsaturated fats. The nuts (almonds and Brazil nuts), seeds (sesame seeds and research suggests that polyunsaturated omega-3 fats may tahini – sesame seed paste), pulses (peas, beans, lentils and help some people with arthritis and other inflammatory soya products such as calcium-set tofu and calcium-enriched conditions. The fact that people also tend to lose weight on soya milk). For more information on calcium see the VVF’s a vegan diet contributes further to its beneficial effects. fact sheet Boning up on Calcium.
  • 17.
    17 Iron Omega-3s and arthritis Some arthritis sufferers may be concerned about their For some arthritis patients, omega-3 supplements may be iron intake, particularly – they may be told – if they avoid helpful, for example a tablespoon of flaxseed oil twice a eating red meat. This should not be a concern as the British day (this exceeds the 1 teaspoon-a-day recommendation Medical Association and the American Dietetic Association for normal consumption). If this is helpful, it may be a good agree that vegetarians are no more likely to suffer from iron idea to try to reduce your intake to the lowest effective deficiency than meat-eaters (BMA, 1996; American Dietetic dose. Association, 2003). Indeed one of the largest studies of vegetarians and vegans in the world (the EPIC Oxford Additional treatments cohort study) looked at over 33,883 meat-eaters, 18,840 Some arthritis patients have benefited from taking a vegetarians and 2,596 vegans and found that the vegans herbal remedy isolated from Rosa canina, a type of rose had the highest intake of iron, followed by the fish-eaters, hip (Winther et al., 2005). In a randomised, double-blind, vegetarians then the meat-eaters (Davey et al., 2003). Cow’s placebo-controlled trial, published in the Journal of milk and dairy products are an extremely poor source of Rheumatology, 82 per cent of patients reported a reduction iron, containing hardly any, whereas pulses, dried fruits and in pain after just three weeks of active treatment with dark leafy vegetables are all excellent sources. For more this herbal remedy. The authors of the study concluded information on iron see the VVF’s fact sheet Ironing out the that it could alleviate symptoms of osteoarthritis. In fact Facts. pain was reduced to such an extent that there was a significant decrease in the consumption of painkillers such Antioxidant action as paracetemol, ibuprofen and NSAIDs. This compares The antioxidant vitamins A, C and E are thought to protect favourably to glucosamine, currently the most popular against disease (and aging) by defending the body against supplement for joint health (Reginster et al., 2001; Matheson and Perry 2003). attack from harmful molecules called free radicals. These damaging molecules are produced naturally as your body Summary breaks down food, or as a result of exposure to harmful Losing weight, eating a healthy plant-based diet that chemicals (including cigarette smoke) or radiation. includes a good supply of omega-3 fatty acids (either though foods or supplements) can help reduce the The damage caused by free radicals plays a role in many symptoms of arthritis and may help some people reduce diseases including cancer and arthritis. A particular class of their medication (ARC, 2006). free radicals (called reactive oxygen species) can promote the inflammatory response that occurs in rheumatoid Multiple sclerosis arthritis (Filippin, 2008). A molecular mechanism linking In multiple sclerosis (MS), the protective sheath (called free radicals to inflammation has been proposed. It myelin) that surrounds the nerve fibres of the central suggests that free radicals activate molecules called nervous system becomes damaged. This process is called transcription factors (nuclear factor-kappa B or NF- B). demyelination. Sclerosis means scarring and multiple refers These then activate genes involved in inflammatory and/ to the many different sites at which the scarring may occur or autoimmune responses. In other words, free radicals can in the brain and spinal cord. Demyelination interferes cause a sequence of events rather like a line of dominos with the messages that are sent between the brain and falling down, which may lead to inflammatory arthritis. other parts of the body. Symptoms can include blurred vision, paralysis, slurred speech, lack of coordination and There is some evidence that anti-rheumatic drugs may incontinence. The severity of symptoms depends on how exert their therapeutic effects by acting as antioxidants. For much damage has occurred. example, non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to act as free radical scavengers (Merry et MS is the most common disease of the central nervous al., 1991). This means they may protect against the harmful system (the brain and spinal cord) affecting young adults effects of free radicals by ‘mopping them up’. However, in the UK. It currently affects around 85,000 people in the antioxidants may be more useful in preventing damage UK and can occur at any age, but in most cases symptoms before it occurs, rather than treating an already inflamed first appear between the ages of 20 and 40. Women are joint. almost twice as likely to develop MS as men. The majority of patients with MS have the relapsing-remitting form of the Too much iron in the blood can encourage the production disease, characterised by attacks or relapses interspersed of free radicals (McCord, 2004). Unlike the non-haem iron with periods of recovery or remission (Harbige and Sharief, we find in plant foods, haem iron in meat is absorbed 2007). It is a life-long condition, but it is not terminal and into the body whether it is needed or not. Thus meat can people with MS can expect to live as long as anyone else supply an overload of iron (but no vitamin C and very little (NHS Direct, 2008c). vitamin E). Conversely, vegetables and wholegrains foods can supply as much or as little iron as is required, as well as The cause of MS is not yet fully understood but is thought an abundance of protective antioxidant vitamins, fibre and to be an autoimmune disease (like rheumatoid arthritis other nutrients. or type 1 diabetes) whereby the body’s immune system
  • 18.
    18 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils attacks its own tissues having ‘mistaken’ them for an distribution of MS and hypothesised that dietary fat intake invading (foreign) protein. This process is referred to as may contribute to progression of MS. ‘molecular mimicry’ as part of the foreign protein closely resembles part of certain cells in our own body. If this Swank suspected animal foods high in saturated fats may all sounds a bit complicated, just think of it as ‘friendly be responsible as MS seemed to occur most among inland fire’ – when a soldier mistakenly attacks one of his own. In dairy-consuming populations and less among coastal fish- autoimmune diseases, the body attacks itself. eating populations. His best known trial, published in the Lancet in 1990, followed 144 MS patients for a total of 34 As with other autoimmune diseases, it is thought that a years (Swank and Dugan, 1990). Swank prescribed a low- combination of genetic factors and environmental factors saturated fat diet to patients with relapsing-remitting MS causes the disease. There is undoubtedly an element of and observed how their conditions progressed. Results genetic predisposition in MS but the evidence suggests that showed that those who adhered most closely to the diet this disease is more strongly related to environmental factors derived the greatest benefits from the intervention. The than genes. In other words, a person may have a genetic beneficial effects were strongest in those who began to predisposition to the disease but not develop it unless follow the diet early in their disease. exposed to a specific environmental ‘trigger’. Such triggers may include bacteria, viruses or components of the diet. In 2000, 15 patients who had been on the diet for 50 years were re-assessed. Of these, 13 were able to walk without Geographical pattern difficulty, the other two required assistance with walking One of the most intriguing features of MS is that it occurs (Swank and Goodwin, 2003). Swank concluded that if people more in countries that are far from the equator. For example, with MS adhere to the diet, with no more than 10-15 grams MS is relatively common in the UK, North America and of saturated fat per day, they can expect to survive and be Scandinavia, but hardly ever occurs in countries such as ambulant and otherwise normal to an advanced age. Malaysia and Ecuador (NHS Direct, 2008c). The reason for this is not fully understood, but it could be that MS is Although Swank’s diet restricted meat and dairy foods, triggered by a particular bacteria or virus which thrives it did include fish and fish oils. More recently, another in cooler climates. Alternative theories suggest that study recommended a co-called ‘quasi’ vegan diet with components of particular foods consumed in these countries fish oil (McCarty, 2001). This study concluded that a may be responsible. whole-food vegan diet, coupled with fish oil and vitamin D supplementation, may represent a practical strategy for Diet and MS the prevention of autoimmune diseases, while concurrently Research suggests that some components in food can act as lowering the risk of many other life-threatening Western causative agents of autoimmune disease. For example, there diseases. Both regimes overlook the fact that you can have is strong evidence that proteins found in cow’s milk can an omega-3 rich vegan diet (containing ALA and an algal trigger an autoimmune response leading to type 1 diabetes supplement containing DHA and EPA if desired) without in genetically susceptible children. The theory with MS is exposing yourself to the toxins found in oily fish and fish that proteins from certain foods (such as cow’s milk) may also oils. prompt the immune system to respond inappropriately and attack the myelin sheath in the brain and central nervous Polyunsaturated fatty acids and MS system. A large body of evidence shows that populations Some research indicates that polyunsaturated fatty acids that consume high quantities of animal-based foods seem to (particularly omega-6 fats) have a role in the chain of be most affected by MS (Agnello et al., 2004). This inevitably events leading to, and the treatment of, MS. Studies show has drawn attention to the role of meat and dairy foods in that omega-6 levels are lower in MS patients. It has been the development of MS. suggested that the way omega-6 fatty acids are normally processed in the body is disrupted in people with MS. Numerous studies have revealed a striking association between the geographical pattern of MS and that of meat In a randomised, double-blind trial of a high dose and and dairy consumption (Arganoff and Goldberg, 1974; low dose omega-6 GLA-rich (borage) oil and a placebo Butcher, 1976; Lauer, 1994). There is also strong evidence control, the high dose had a marked clinical effect in linking a high intake of saturated fat to the incidence of relapsing-remitting MS. Results showed that the GLA- MS. Taken together, the evidence shows that foods rich in rich oil significantly decreased the relapse rate and the saturated fats are associated with higher levels of MS while progression of disease (Harbige and Sharief, 2007). The foods rich in polyunsaturated fats are linked to lower levels authors of this study suggested that disturbed omega-6 (Harbige and Sharief, 2007). fatty acid metabolism in MS gives rise to a loss of both long chain omega-6 fatty acids in the membranes and anti- The research investigating the links between diet and MS inflammatory cytokines, particularly during the dates back 60 years to Dr Roy Swank’s work first at the relapse phase. Montreal Neurological Institute in Norway, then at the Division of Neurology at the University of Oregon Medical The loss of these important neural fatty acids in central School in the US. Swank was intrigued by the geographical nervous system structure and function may have long-term
  • 19.
    19 consequences in MS.However, this feature of MS can be nutrients required for good health and reduce some of the treated by supplementation (Harbige and Sharief, 2007). In risk factors for autoimmune diseases or prevent making an general, it appears that over time, diets low in saturated fat, already existing condition worse. but containing both some omega-6 and omega-3 fats, can improve the course of MS (Harbige and Sharief, 2007). As the incidence of most autoimmune diseases correlates directly to the consumption of animal foods, a move In 2007, a Cochrane review concluded that polyunsaturated towards a more a plant-based diet could help combat the fatty acids seemed to have no major effect on the main rise in these conditions among populations that currently clinical outcome in MS (disease progression) (Farinotti et consume high levels of dairy and meat products. al., 2007). However, only a limited number of studies was reviewed and they did state that the data available were Allergies insufficient to assess any potential benefit or harm from Some research suggests that the dramatic increase in the supplementation. Clearly more research is required to consumption of omega-6 fats, coupled to the decrease in assess the effectiveness of dietary interventions in MS. In the omega-3 fats consumed, is a major driver of the increase meantime, over 50 per cent of people with MS make dietary of a range of inflammatory allergic reactions (Chilton et al., changes and take supplements (Farinotti et al., 2007). 2008). Polyunsaturated fats and autoimmunity Asthma It is generally accepted that omega-6 fatty acids are pro- Asthma is a chronic inflammatory lung disease inflammatory (Harbige, 2003). However, while they have characterised by recurrent breathing problems. The UK has been shown to increase the severity of some autoimmune one of the highest prevalence rates for asthma in the world, and inflammatory diseases, omega-6 fats may actually along with New Zealand, Australia and Ireland. Around one protect against other (immune-mediated and non-immune- in eight children and one in 20 adults are currently being mediated) inflammatory diseases. Therefore, the view that treated for asthma in the UK. all omega-6 fats are pro-inflammatory is incorrect (Harbige, 2003). During an asthma attack, the lining of the airways becomes inflamed and the airways constrict. This can lead to the There is some evidence that omega-3 fats can ‘dampen characteristic symptoms of asthma such as coughing, down’ inflammatory responses. This anti-inflammatory wheezing, difficulty in breathing and tightness across the role may offer short-term benefits in some autoimmune chest. diseases. However, this could be an undesirable long- term effect of high-dose fish oils, as it could compromise The causes of asthma are thought to include a genetic immunity (Harbige, 2003). As stated earlier, the predisposition (asthma in the family) and environmental inflammatory response is a natural part of our immune triggers such as cigarette smoke, chemicals, dust mites and system and can help fight infection. In other words, a high diet. As food allergies are responsible for approximately intake of fish oils may not be beneficial in the long term; it five per cent of all asthma cases (James et al., 1994) and may weaken the immune system while only addressing the as cow’s milk is a primary cause of food allergies, it seems secondary consequences of an autoimmune response. reasonable to consider avoiding all cow’s milk and dairy products in the treatment of asthma. Diets low in saturated fat and relatively high in omega-3 fats (higher than the low amount present in most UK diets) Asthma may also respond to other dietary modifications, can reduce the severity of some autoimmune diseases. thereby reducing the need for medication. Studies show Conversely, diets high in the omega-6 fat LA may increase that supplementing the diet with plant-based fatty acids the severity of these conditions (Harbige, 2003). However, can inhibit inflammatory responses leading to asthma. One as stated previously, there is convincing evidence for a study found that supplementing the diet with omega-6 and protective role of both omega-6 and omega-3 fats in MS omega-3 fats in a ratio of 2:1 helped alleviate symptoms, (Harbige, 2003). whereas a ratio of 10:1 made symptoms worse (Broughton et al., 1997). In conclusion, moderate intakes of omega-6 fats and the appropriate ratio between omega-6 and omega-3 fats are Another study found that supplementing the diet with important for the correct functioning of the immune system borage oil (containing GLA) led to the accumulation of (Harbige, 2003). Adjusting the ratio could be helpful in natural inhibitors of leukotrines (hormones that cause the autoimmune or inflammatory disease. The optimum ratio symptoms of asthma) within inflammatory cells (Chilton et varies depending on age and the basis of the autoimmune al., 2008). This concurs with the research described above disease. that shows that GLA provides an exception to the usual pro- inflammatory role attributed to omega-6 fats. This all sounds rather complicated but the overall message is that a plant-based diet, low in fat, salt, sugar The overall optimum ratio of omega-6 to omega-3 fats may and processed foods and high in fresh fruit, vegetables, vary according the disease and the patient (age, sex and wholegrains, pulses, nuts and seeds can provide all the physical condition) but the message that we all need to
  • 20.
    20 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils increase our intake of omega-3 fats while not increasing that Omega-3 fats have been identified as potentially helpful. of omega-6 fats is consistent throughout the research. Many people cannot tolerate the taste or smell of fish oils, even when provided in capsules. Because of this, and Eczema dwindling fish stocks, interest in plant-based sources of The increasing rate of eczema in the West has been linked omega-3 fatty acids has increased tremendously (Chilton et to a steep rise in the consumption of omega-6 fats and the al., 2008). reduced intake of omega-3s (Koch et al., 2008). Omega-6 fats favour the formation of specific eicosanoids (hormone- Most fat eaten in excess of requirements is stored in like molecules) that are involved in allergic inflammation. adipose tissue in the form of triglycerides (three fatty acids The parent omega-6 fatty acid LA is converted into combined with glycerol). Many diseases feature elevated arachidonic acid, a precursor in the production of levels of triglycerides: cardiovascular diseases, asthma, eicosanoids (Koch et al., 2008). Consequently an increased diabetes, obesity and arthritis. There is tremendous interest intake of omega-6 fats can promote allergic reactions, in plant-based oils and supplements (as an alternative to while increasing omega-3 intake competes with omega-6 fish oil) as a source of omega-3 fatty acids for protection metabolism and protects against inflammatory conditions. against these chronic diseases. Researchers from the Center for Botanical Lipids at Wake Forest University in The results of a recent exploratory trial were published in North Carolina state that botanical (plant-based) oils hold the British Journal of Dermatology (Koch et al., 2008). This particular promise for modulating inflammatory responses study reported how 53 patients suffering from eczema were (Chilton et al., 2008). randomly allocated supplements of both DHA and EPA, or a control (caprylic acid, otherwise known as octanoic acid, A large number of vegetarian and vegan studies show that an eight-carbon saturated fatty acid) daily for eight weeks. plant-based diets offer numerous health benefits, including Results showed a considerable improvement in the group the prevention and therapy of many chronic diseases taking DHA/EPA supplements. The authors suggested that including arthritis (Leitzmann, 2005). Since vegetarian and these fatty acids may have an anti-inflammatory role as they vegan diets are more sustainable, environmentally and inhibit arachidonic acid production. While some arachidonic economically, they certainly deserve more consideration acid is essential for your health, too much may make in both the prevention and treatment of disease. This inflammation worse. message needs to filter down from the peer-reviewed studies into our hospitals, schools, workplaces and homes. It was noted that plasma DHA and EPA levels rose two- to threefold following supplementation. The authors Brain food suggested that the higher level of EPA might have resulted The human brain grows and develops very rapidly during from the small but significant amount of EPA in the the first year of life, tripling in size by the age of one. The supplement or from the retroconversion of DHA to EPA. brain is largely made up of fat (over 60 per cent) and early This is important as it indicates that an algal supplement brain development and function in humans requires a supplying DHA could be used to increase both DHA sufficient supply of polyunsaturated EFAs. For humans, the and EPA levels. Again this means you could take an algal omega-6 fat arachidonic acid and the omega-3 fat DHA are supplement and avoid the risk of exposing yourself to toxins essential for brain development and functioning. that may be found in fish oil supplements. Although human breast milk and cow’s milk contain a Summary similar amount of total fat, the proportion of saturated and Our genes take a very long time to change and are still very unsaturated fats in each is very different. This difference similar to the genes of our ancestors during the Palaeolithic contributes to the unsuitability of cow’s milk for human era 40,000 years ago, when the human genetic profile infants. The high level of unsaturated fats in human breast was established (Simopoulos, 2008). The same cannot be milk reflects the crucial role these fats play in human said for our diet. Anyone can see our diets have changes brain development. A rapid increase in body size is more hugely – our ancestors would have been hard pushed to important for cows, so they produce milk high in body- find burger, chips and a milkshake! But does this matter? building saturated fats to help their calves grow quickly. Well, studies on the evolutionary aspects of diet indicate that the major changes that have occurred have altered A review of 20 studies of cognitive (brain) function of the type and amount of essential fatty acids in our diets breast-fed infants compared to that of formula-fed infants (Simopoulos, 2008). So while in many ways our bodies are concluded that the nutrients in breast milk may have a potentially the same as those of our ancestors, the way we significant effect on neurological development in infants fuel it has changed drastically. This is like expecting a car (Anderson et al., 1999). Indeed, a longer duration of to run on a lower grade fuel than it was designed for. There breastfeeding is associated with significantly higher scores will inevitably be problems with the engine. in verbal, performance and IQ tests (Mortensen et al., 2002). So breast really is best! The increase in heart disease, arthritis, allergies and other health problems has encouraged some scientists Attempts to alter the fatty acid composition of cow’s to investigate the role of diet in these and other diseases. milk, in order to meet human requirements, have involved
  • 21.
    21 experiments feeding cowsfish meal and soya beans (Abu- 80 per cent fish oil and 20 per cent evening primrose Ghazaleh et al., 2004) and flaxseed (Petit, 2002). Feeding oil in gelatine capsules. The daily dose of six capsules flaxseed resulted in a lower omega-6 to omega-3 fatty acid provided omega-3 fatty acids (558 mg of EPA and 174 mg ratio, which might improve the nutritional value of milk for of DHA) and the omega-6 fatty acid LA (60 mg), or olive oil humans. Of course you could just eat flaxseed oil yourself to (omega-9) as a placebo. improve the balance of omega-3 and omega-6 oils in your diet while avoiding the many undesirable components of After three months of treatment, results showed significant cow’s milk and oily fish. improvements in reading, spelling and behaviour among those receiving the fish oil supplements. The researchers Smart enough to be veggie? concluded that fatty acid supplements may be a safe, Fish oils have been sold as a magic bullet for boosting tolerable, effective treatment for improving academic brain power. As the term ‘essential’ implies, we certainly progress and behaviour among children with DCD. In other do need some EFAs in the diet. However, contrary to the words, children who are not fulfilling their potential may intensive and misleading marketing, fish and fish oils are benefit from increasing their intake of essential fatty acids. not essential for good health. In fact, the fatty acids found The VVF asked the researchers in Durham if they would in fish oil (EPA and DHA) are not defined as ‘essential’; only consider using flaxseed oil in future trials to see if similar the plant-based fats ALA and LA are. These plant-derived results could be achieved without exposing children to EFAs provide a healthier and safer source. Consider this: if potential toxins but our requests were ignored. fish oils were a superior source of fatty acids for brain health then vegetarians would come bottom of the intelligence A follow-up trial was conducted in Durham more recently stakes. The reverse appears to be the case. whereby three million fish oil capsules were given to 2,000 children over eight months to see if their GCSE results Links between intelligence and the vegetarian diet were improved. Unfortunately the GCSE results were rather demonstrated in 2006 when a team of vegetarians won the disappointing, which was not press-released by the County BBC’s Test the Nation IQ battle (the butchers came joint Council. In some very fast back-pedalling they said “...it was fourth; sadly there was not a team of fish-mongers!) never intended, and the County Council never suggested, that it would use this initiative to draw conclusions about More weighty evidence was provided in a study published the effectiveness or otherwise of using fish oil to boost in the British Medical Journal which showed that intelligent exam results.” So it seems fish oil was not the magic bullet children are more likely to become vegetarians later in Durham Council was looking for. life (Gale et al., 2007). Researchers from Southampton University found that people who are vegetarians by the It is interesting to note that the fish oil capsules used in the age of 30 had an IQ five points higher than the average IQ Durham trial cost 80p per child, per day, rather more than when they were 10. This might explain why people with a the 65p Durham Council was spending per child per day higher IQ are healthier: vegetarians generally suffer less on school meals at the time. In 2008 the cost of ingredients heart disease, hypertension, obesity, diabetes, various had risen, but to just 80p for a secondary school child per cancers, diverticular disease, bowel disorders, gallstones, day (Durham Council, 2008). Rather than looking for a magic kidney stones, and osteoporosis. bullet, improving the quality of school meals and education about diet and health would perhaps have been a better The obvious point here is that if omitting fish and fish oils approach. from the diet led to a lower cognitive ability, non-fish eating children and adults would come bottom in the intelligence Most children in the UK eat such appalling diets that stakes. There has never been any study to suggest this is nutritional deficiencies are inevitable. Correcting such the case and thousands of healthy intelligent vegetarian deficiencies will in many cases improve the symptoms and non-fish eating families provide proof that brains associated with that particular deficiency. This is not the function perfectly well without fish oils! same as saying fish oil will turn all kids into geniuses, which is exactly how the media interpreted the findings. ‘Council Fish oils for brainy kids? to include more fruit, vegetable and wholefoods in school So what is the scientific evidence that fish oils can improve meals’ just doesn’t make such an impressive headline as cognitive ability and where does the Government stand ‘magic pill makes kids clever’. on this issue? The evidence comes mainly from trials done using children with behavioural problems and is largely The Joint Health Claims Initiative (JHCI) operated between anecdotal. 2000 and 2007 to ensure a level playing field for the food industry and to increase consumer protection by The Durham-Oxford Study is the most cited work investigating the science behind health claims (JHCI, (Richardson and Montgomery, 2005). In this study, 117 2007). It is no longer in operation as the new EU ‘claims’ children with developmental coordination disorders (DCD) regulation for foods now verifies health claims. However, such as attention deficit/hyperactivity disorder (ADHD), during the seven years of investigating health claims, the dyslexia and dyspraxia were given a daily supplement of JHCI approved claims for soya protein, oats and reduced fatty acids. The treatment was a supplement containing saturated fat all for their cholesterol-lowering effects and
  • 22.
    22 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils for wholegrain foods’ benefits to heart health. They also bigger fish eats smaller fish and so on. Fish at the top of the approved health claims for long chain omega-3 fats for food chain such as tuna, shark, swordfish, tilefish and king maintaining a healthy heart. They did not approve any mackerel, have the highest concentrations of POPs. Algae claims linking omega-3 fats (or fish oils) to cognitive ability. (which are right at the bottom of the food chain) are likely to contain much lower levels. Unfortunately misleading publicity from this and other research has encouraged companies to produce so-called Farmed salmon are even more of a concern than wild functional foods such as St Ivel Advance Omega-3 milk. The salmon due to the concentration of POPs in the feed advertisements implied that this milk may make children they eat and their fatty nature as POPs can accumulate in more intelligent because it contained omega-3 fatty acids fatty tissue. (from fish). The advertisements for this so-called ‘clever milk’ featured the scientist Professor Robert Winston, In 2001, officials from 90 countries signed a landmark lending kudos to the outlandish claims. But following UN treaty in Stockholm, designed to curb the use of complaints, the Advertising Standards Authority (ASA) ruled some of the world’s most dangerous and toxic chemicals that the advertisements were misleading and the claims (Stockholm Convention, 2008). They identified twelve used for the benefits of the milk unproven. The ASA ruled particular substances for banning which later became that as the children in the trial had learning difficulties, there known as the ‘dirty dozen’. The list included eight organo- was no basis to claim there would be an improvement in the chlorine pesticides: aldrin, chlordane, DDT, dieldrin, endrin, concentration of all children. Dairy Crest, the firm behind heptachlor, mirex and toxaphene; two industrial chemicals: the product, withdrew the adverts following the ruling. hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs); and two groups of industrial by-products: dioxins Although the Government has refused to shift its position and furans. on recommending fish oils for heart health, it is clearly not convinced about cognitive benefits. The FSA states that: The Stockholm Convention on POPs came into force on “Evidence on the cognitive benefits of the omega-3 fatty May 17, 2004, with agreement from an initial 128 parties acids, EPA and DHA, which are found in fish oils, is currently and 151 signatories. Co-signatories agreed to ban nine of uncertain,” (FSA, 2008). the ‘dirty dozen,’ limit the use of DDT to malaria control and curtail production of dioxins and furans. Several other Common sense suggests that if the diet provides enough substances are now being considered for inclusion in the EFAs, fish oils may have no additional effect on cognitive Convention. These are: hexabromobiphenyl, octaBDE, ability at all. Encouraging children to eat oily fish in the pentaBDE, pentachlorobenzene, short-chained chlorinated pursuit of cleverness may lead to serious health problems paraffins, lindane, - and -hexachlorocyclohexane, dicofol, due to their exposure to pollutants. endosulfan, chlordecone and PFOS. Not what you’d expect to see in a list of ingredients! However, even though this is a step in the right direction, Contaminated fish are a danger to health it will take many years for POPs (used in everyday items such as plastics, paints and pesticides) to break down. All of the world’s oceans and rivers are polluted with toxic Furthermore, the environmental group, the World Wildlife chemicals; mainly pollutants resulting from decades of Fund has expressed concerns that global warming could increasing industrial activity. The health risks associated increase levels of POPs as higher temperatures may release with the consumption of fish and fish oil supplements chemicals which have been frozen in glaciers. are due to the presence of these toxic pollutants, not to mention the saturated fat, animal protein and cholesterol PCBs they contain. Oily fish such as salmon, trout and mackerel Polychlorinated biphenyls (PCBs) and dioxins are the main may be contaminated with chemicals, while shark, marlin contaminants in oily fish (Consumers’ Association, 2002). and swordfish contain high levels of mercury (Consumers’ Although they are now banned, PCBs have not disappeared Association, 2002). Long-term exposure to these harmful from the environment and won’t for a very long time. substances poses a significant threat to health. The Scientific Advisory Committee on Nutrition (SACN) POP goes the seawall is an advisory committee of independent experts that A particularly nasty class of contaminants found in oily fish provides advice to the FSA, Department of Health and is known as persistent organic pollutants (POPs). These other government agencies and departments. SACN organic pollutants are made up of complex molecules states that: “PCBs are very persistent chemicals which are which do not break down easily in the environment; hence ubiquitous in the environment and are generally present in the name ‘persistent’. They build up in the food chain low concentrations in foods, especially fat-containing foods through bioaccumulation. This means that the level of including milk, meat and fish,” (SACN, 2004). chemicals found in an animal tissue rises the higher up the food chain the animal is. For example, larvae might eat As persistent lipophilic (fat-loving) compounds that some contaminated algae, a fish then eats the larvae, and a accumulate in lipids, PCBs are particularly likely to be present
  • 23.
    23 in oily fish.They are implicated in heart disease, cancer, in antioxidant reactions. Sulfhydryl groups are compounds infertility and can harm developing foetuses by disrupting that contain a functional group composed of a sulphur atom the development of male babies’ reproductive organs. and a hydrogen atom (-SH). They feature as a functional group of the amino acid cysteine and so play an important Dioxins role in many biological systems. By binding to sulfhydryl Dioxins were the primary ingredient in Agent Orange, groups, mercury inactivates antioxidative compounds, the defoliant sprayed over Vietnam which has produced again, increasing free radical activity. Taken together, these an appalling legacy of cancers and other diseases, reactions indicate how mercury could inhibit important miscarriages and birth defects. As stated, these insidious antioxidative mechanisms in humans. In other words, the toxins build up in the body over time. The FSA points out high mercury content in fish can not only counteract the that: “If a woman changes her diet when she becomes protective effects of the fatty acids found in oily fish, but pregnant, or when she starts trying for a baby, this won’t may go on and do serious harm to health. change the levels of dioxins and PCBs that are already in her body. So it’s a good idea to limit the amount of oily fish For non-oily fish, there seems even less reason to take the eaten from a young age.” risk of exposing yourself to mercury. Numerous studies have reported an association between fish intake and coronary Furthermore, contrary to previous advice that these toxic mortality. In 1995, one study investigated why men in pollutants are only found in oily fish, the FSA states that: Eastern Finland have an exceptionally high level of mortality “Recent surveys have shown that some other fish and crab from CVD (Salonen et al., 1995). This study measured hair may also have similar levels of dioxins and PCBs as oily fish. mercury content in healthy individuals and then recorded These fish are: sea bream, turbot, halibut, dog fish or huss, CVD events (such as heart attacks) over the following years. and sea bass.” Now they tell us! The mercury content in Finnish lakes is known to be Mercury rising relatively high; especially so in ground waters (water that Methylmercury is the organic form of mercury found in supplies wells and springs) in Eastern Finland. This study the environment, usually as the result of industrial pollution. found that an average daily fish intake of just 30 grams This toxin is commonly found in the marine environment or more was associated with a two-fold increase in heart and accumulates up the food chain particularly in older, attack risk. For each additional 10 grams of fish per day larger fish. Mercury affects the kidneys, heart and central there was an increment of five per cent in the five-year risk nervous system (CNS). Exposure is particularly hazardous of heart attack. This indicates that mercury, even in subtoxic for unborn children where the main organs and the CNS amounts, is a risk factor for coronary and fatal CVD. The are still developing. Women and girls who may have authors concluded that because in many countries fish children one day are advised to eat less oily fish than and seafood are contaminated with mercury and because men and older women because mercury can harm the fish is eaten all over the world, their findings could be of development of unborn children. The FSA states that adults enormous public health importance. should have no more than one portion of swordfish, shark or marlin a week because these fish contain high levels of A later study (from the same group) investigating the mercury (FSA, 2009). association between blood levels of the omega-3 fats EPA and DHA, and the risk of acute coronary events in middle- While some studies indicate that high intakes of oily fish, aged men from Eastern Finland, again looked at mercury or fish oil supplements, are associated with a reduced levels in hair (Rissanen et al., 2000). This prospective risk of CVD, others have suggested that fish oils can population-based study of 1,871 men confirmed that increase the risk. In these studies, mercury is suspected high levels of DHA in the blood were associated with a as being responsible for the harmful effects seen as it can decreased risk of acute coronary events. However, the accelerate atherosclerosis and increase the risk of heart men who fared best in this comparison were those with attack. Possible mechanisms by which mercury exerts these high DHA levels and low mercury content in the hair. It damaging effects include promoting the peroxidation of was concluded again that mercury could cancel out any unsaturated fatty acids (Salonen et al., 1995). This is the protective effect offered by the fats in oily fish. process whereby damaging molecules called free radicals ‘steal’ electrons from the fats in cell membranes, resulting A case-controlled study published in the New England in cell damage. Journal of Medicine in 2002 conducted in eight European countries and Israel provided further evidence linking Mercury also forms an insoluble complex with the mercury in fish to CVD. This study investigated the antioxidant mineral selenium. It binds it in an inactive relationship between mercury levels in toenail clippings form preventing selenium from acting as a cofactor for the and DHA levels in adipose tissue with the risk of a first heart protective enzyme glutathione peroxidase. This enzyme’s attack among men (Guallar et al., 2002). This study included main biological role is to protect the body from oxidative 684 men in the coronary care units of participating hospitals damage. Binding selenium in this way can lead to an who had experienced their first heart attack. Also, 724 men increase in free radical activity. Mercury also has a very high representative of the same population (but who had not affinity to sulfhydryl groups which play an important role had a heart attack) were selected to act as controls. Results
  • 24.
    24 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils showed that while higher DHA levels were associated with group over another. This has lead to a failure to pay enough a lower heart attack risk, the toenail mercury level was attention to the role of contaminated fish and shellfish in directly associated with an increased risk of heart attack. food poisoning. The authors of this study suggest that The authors concluded that mercury may diminish the relying solely on the literature has lead to an over-emphasis cardioprotective effect of fish intake. on controlling the milk supply and a failure to pay enough attention to the role of contaminated fish and shellfish in They also warned that exposure to mercury is already food poisoning. a concern in specific high risk groups and suggested extending the US Food and Drug Administration’s When they are raw or haven’t been cooked properly, fish and recommendation that pregnant women and women who shellfish can contain a range of harmful viruses and bacteria. may become pregnant do not eat swordfish, king mackerel, Shellfish (such as clams, mussels and oysters) are also filter tilefish or tuna to include the entire population. feeders, constantly filtering water, which can lead to the accumulation of pollutants. The FSA recommends that elderly A statement from the American Heart Association people and people who are unwell might want to avoid (AHA) acknowledges the discrepancy in the findings of eating raw shellfish to reduce their risk of food poisoning research on fish oils and CVD (Kris-Etherton et al., 2002). (FSA, 2008d). Most shellfish is eaten cooked, but oysters are They acknowledge that the contradictory findings of often served raw and can contain a virus called the Norovirus. these studies could be explained by the adverse effects Raw or partially cooked shellfish can also contain hepatitis A, of mercury, which they say may diminish the health which is a highly contagious virus of the liver. benefits of omega-3 fatty acids from fish. They conclude that while collectively, the research is supportive of the For these reasons, the VVF argues that sea vegetables recommendation to include at least two weekly servings of (seaweed) are the true ‘fruits de mer’ or fruits of the sea, not fish (particularly fatty fish), this recommendation must be shellfish. Not only do they add flavour to food, each variety balanced with concerns about environmental pollutants, in is a low-fat nutritional powerhouse, packed full of vitamins particular PCB and methylmercury. This ambiguity can only and minerals. Plus, you won’t find elevated levels of dioxins, add to the confusion! PCBs or mercury in sea vegetables, in contrast with fish and shellfish in whose body fats these pollutants accumulate They do however point out that the research supports the over time. inclusion of vegetable oils (soya bean, rapeseed, walnut and flaxseed oils) and food sources (walnuts and flaxseeds) high The FSA’s website provides an extensive list of in ALA in a healthy diet for the general population. This, at precautionary measures people should take when buying, least, is a move in the right direction. storing and preparing fish. It lists 18 different ways you can minimise the risk of being poisoned (FSA, 2009). Of Food Poisoning course just avoiding fish and shellfish would be much Food poisoning generally happens when someone eats easier. Indeed excluding all animal foods from the diet will food that is contaminated with bacteria or its toxins. dramatically decrease the risk of food poisoning. According to the FSA, it is estimated that up to 5.5 million people in the UK are affected by food poisoning each year Fish and PhIPs (NHS Direct, 2008d). However, it is difficult to know exactly Most people think the fool-proof way to avoid food how many people are affected as not all of those affected poisoning from meat and fish is to cook it very well – some seek medical advice. people practically cremate it to make sure. However, thoroughly cooking meat and fish can lead to even more Most cases of food poisoning result from eating serious problems. contaminated animal products (meat, poultry, eggs, dairy, fish and shellfish) as plants tend not to harbour the types of Cancer-causing compounds called heterocyclic amines bacteria capable of causing food poisoning in humans. If (HCAs) are formed when meats (such as beef, chicken and plant foods do cause food poisoning it is generally because pork) and fish are cooked at high temperatures (Wilson et al., they have been contaminated with animal excreta, human 2007). HCAs form when a chemical found in muscles called sewerage or prepared with dirty hands. creatine reacts with amino acids (the building blocks of protein) and sugar at high temperatures. While meat While most food poisoning incidents are associated with and fish contain significant amounts of creatine, vegetables meat and poultry, the links between fish, shellfish and contain none. food poisoning should not be discounted. Researchers from the Health Protection Agency Centre for infections In 2005, the US federal government officially added HCAs in London looked at a number of cases of food poisoning to its list of known carcinogens (US Department of Health in the UK between 1992 and 2003 (O’Brien et al., 2006). and Human Services, 2008). The most abundant HCA Of the 1,763 cases reported to national surveillance, only found in the human diet is called 2-amino-1-methyl-6- 55 were published in the peer-reviewed literature. As this phenylimidazo[4,5-b] pyridine (PhIP). PhIP is associated with type of publication tends to favour the unusual or novel an increased risk of cancer of the colon, breast and prostate event, coverage can lead to an over-emphasis of one food (Wilson et al., 2007).
  • 25.
    25 Exactly how PhIPincreases cancer risk is uncertain. It has per day. Providing a similar diet to farmed fish would mean been suggested that PhIP produces harmful molecules grinding up to 10 pounds of sardines, anchovies, mackerel, called reactive oxygen species which cause DNA strands herring and other fish for every pound of pale and sickly to break thus increasing cancer risk (Wilson et al., 2007). farmed salmon produced. This is clearly uneconomical for Alternatively, researchers at Imperial College in London fish farmers and heralds an ecological disaster as one-third have reported that PhIP is a potent mimic of the hormone of the global fish catch ends up as fishmeal or fish oil and oestrogen (Lauber et al., 2007). This is very worrying, as fish farms use about half of the fishmeal and more than 80 many studies link higher oestrogen levels to breast cancer. per cent of the fish oil (Soil Association, 2008). This theory provides a plausible explanation for why diets rich in red meats are linked to an increased risk of breast It is much cheaper to manufacture feed pellets from soya, cancer. rapeseed or corn with animal by-products and vitamin and mineral supplements. In Canada and Chile, it is common to In 2005, the Physician’s Committee for Responsible use other protein sources such as feather or blood meal by- Medicine’s Cancer Project revealed that grilled salmon was products of chicken and pig production (Soil Association, among the five worst foods to grill (PCRM, 2005). The Cancer 2008a). Consequently, farmed fish tend to contain more Project nutritionists found that many commonly grilled total fat, but less omega-3s than their wild counterparts foods contain alarmingly high levels of HCAs. The five foods (Weaver et al., 2008). In other words, the levels of good and containing the highest levels included: chicken breasts, steak, bad fats (the fatty acid profile) of farmed fish vary widely pork, salmon and hamburgers. from that of wild fish. The amount of PhIP in some foods may typically lie in the Using cheaper vegetable-based feeds drives up the level region of 35 nanograms per gram. However, there are of omega-6 fats found in the fish. Farmed tilapia (the some reports of much higher levels of PhIP (Skog, 2002). most rapidly expanding fish in terms of world and US Concentrations of PhIP in fish vary widely according to consumption), contain some of the highest levels of the the type of fish and method of cooking. One study reported omega-6 fatty acid arachidonic acid found in our food levels ranging from 1.7 to 73 nanograms per gram in salmon chain (Weaver et al., 2008). These and other farmed fish cooked at 200°C by various methods (Gross and Grüter, 1992). have a fatty acid profile that would generally be considered as unhealthy. Indeed, marked changes in the fishing The damaging action of HCAs may be reduced by foods industry during the past decade have produced widely containing antioxidants, such as vegetables and soya foods eaten fish that have fatty acid characteristics that are (Weisburger, 2002). However, the safest option is to avoid generally accepted to be inflammatory by the health care meat and fish altogether. Healthier options for grilling and community (Weaver et al., 2008). frying include soya burgers, veggie sausages and Portabella mushrooms. The fish used in organic fish feeds come from the discarded filleting wastes (blood, guts, tails and heads) of fish caught for human consumption and should not contain fish caught specifically for fish feed. However, this does mean the Farmed and dangerous supply is sustainable; human demand for fish also exceeds supply. Compared to conventional fish feed, organic fish Unless you seek out wild fish, the chances are that most of feed may use more fish-based ingredients than non-organic the fish you see in shops and restaurants were raised on a fish feed but still might only have 40 per cent fishmeal and fish farm in an environment very different to what their wild about 22-25 per cent fish oil (Soil Association, 2008a). This counterparts would have experienced. One of the main means that 35 per cent of the feed could be vegetable- differences on many fish farms is the stocking density – based. imagine having to fight your way through the January sales every day just to get something to eat. This is the type of Farmed fish can also contain chemical pesticide residues scenario many farmed fish endure. as well as dangerous levels of toxic man-made chemicals including PCBs. A 2002 study investigating the levels of Fish species raised by fish farms include salmon, catfish, toxins in commercial salmon feeds, farmed salmon and tilapia, cod, carp, trout and others. Just as we see with wild salmon found that the farmed salmon had consistently other farmed animals such as the dairy cow, intensive higher levels of a range of contaminants including farming methods results in a cheaper end product (in PCBs (Easton et al., 2002). The authors suggested that terms of quality and price). This is why farmed salmon has the higher levels seen in the farmed salmon probably been called ‘the battery chicken of the seas’. This may not resulted from the elevated level of contamination found concern you if the supposed health benefits are the same. in the commercial salmon feed. They concluded that this However, they are not. analysis indicates a safety concern for individuals who, on a regular weekly basis, consume farmed salmon produced From a nutritional and health perspective, there are several from contaminated feed. Since then, other studies have important differences between farmed and wild fish. In indicated that commercial feed is likely to be a major the wild, salmon can eat 10 times their own body weight source of PCBs in farmed salmon (Carlson et al., 2005).
  • 26.
    26 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils So, farmed fish are very far from the safe choice we are occasionally eating more than the recommended amounts led to believe and from a health perspective, when fish of oily fish will not be harmful. It says that the risks from are farmed, they lose some of their protective fats. This is chemicals such as dioxins are not immediate; they develop a ridiculous situation where the one possible argument in as the chemicals accumulate in the body over a long favour of fish consumption (their omega-3 content) is being period of time. Surely it is better to avoid these hazardous eroded by intensive farming methods. There remains little, chemicals altogether? if any, argument for consuming fish. Confused? You will be! The FSA advises that fish oils protect against CVD and that long chain omega-3s are vital for the development of the Fish oil supplements central nervous system of the foetus and the breast-feeding infant (SACN, 2004). However, the FSA warns pregnant Some people prefer to take fish oil supplements rather than and breast-feeding women to restrict their intake of oily eat oily fish. However, fish oil supplements have also been fish to limit their exposure to harmful toxins. So just when linked to negative health effects in numerous studies. This your intake of omega-3 really matters, during pregnancy is particularly worrying as they are increasingly popular as and when you are breastfeeding, the Government warns clever marketing persuades people to buy them. you to limit your intake! Consumers are unsurprisingly confused; the information given is neither comprehensive Most fish oil supplement manufacturers publicise their nor consistent. meticulous manufacturing techniques reassuring us that all toxins are removed from their products. However, in March In 2002, Which? magazine reported the findings of a 2006, the FSA announced that the fish oil supplement Consumers’ Association survey which asked 972 adults manufacturer Seven Seas Ltd withdrew a number of about their awareness of, eating habits and attitudes to batches of its own fish oil supplements because the levels oily fish (Consumers’ Association, 2002). The survey found of pollutants present (FSA, 2006). Less than a month later that only a sixth of fish-eaters knew that the FSA’s advice Boots withdrew fish oil capsules for the same reason (FSA, is to eat oily fish once a week; over half thought the advice 2006a). In both cases they said although there was no was to eat two or more portions. A shocking 61 per cent of health risk associated with consumption of this product, people had no idea that oily fish may contain contaminants. the level of dioxins found in fish oil used to produce One per cent knew that pregnant women should avoid these capsules exceeded statutory limits. This is a bizarre certain fish but nobody could name them. Most people in statement which seems to be saying that a little bit of the survey were confused by what was meant by oily fish poison should be all right! (14 per cent thought that cod was an oily fish). It is not just the public who are confused; the Consumers’ Association states that the FSA couldn’t provide any clear answers about the health implications of eating more than one The official position – not budging portion of oily fish per week. The seriousness of the potential health risks of consuming toxins in fish prompted a joint subgroup of two advisory It’s no clearer in the US. In 2002 the American Heart committees, the Scientific Advisory Committee on Association (AHA) issued a statement supporting Nutrition (SACN) and the Committee on Toxicity the recommendation for at least two servings of fish of Chemicals in Food, Consumer Products and the (particularly oily fish) per week (Kris-Etherton et al., 2002). Environment (COT), to consider the benefits and risks of However, the AHA warned that the recommendations fish consumption (SACN, 2004). on fish consumption need to be balanced with concerns over contamination of fish with environmental pollutants Their report formed the basis of the FSA advice that (particularly mercury and PCBs). This is an incredibly pregnant and breastfeeding women should limit their important proviso which seriously challenges the idea consumption of oily fish to one to two 140 gram portions that fish is ‘healthy’. It should be noted that the AHA per week. This group (and children under 16) they say, also recommended plant foods that are high in the plant should avoid shark, marlin and swordfish and not eat large omega-3 ALA such as soya beans, rapeseed, walnuts and amounts of tuna because of the potential methylmercury flaxseed and oils made from them. exposure. Men, boys and women past childbearing age or who are not intending to have children can eat up to four In the joint WHO/FAO 2003 report Diet, Nutrition and portions of oily fish a week before the possible risks might the Prevention of Chronic Diseases, regular fish start to outweigh the benefits. consumption of one to two servings per week is recommended to protect against CVD (WHO/FAO, 2003). The report highlights the presence of dioxins in herring, However, whilst it also states that vegetarians can ensure salmon, mackerel and to a lesser degree in trout, and adequate intakes of the omega-3 fatty acid ALA from plant voices concerns about the presence of other pollutants sources, the report fails to give any warnings about the such as brominated flame retardants. The FSA states that dangers of environmental contamination.
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    27 This conflicting advicehas led to much confusion. Who EFAs, such as nuts and seeds, possess their own supply of should the public listen to? Who can they believe? antioxidants which protect their fats (in particular vitamin E). So yet again, we see why a plant-based diet provides not Fish is not a popular food only important nutrients, but valuable substances that can Despite the constant barrage of fish-promoting marketing protect us from oxidative damage too. and hype, the UK public just don’t buy it! The FSA says that on average, people in the UK eat only a third of a portion Free radicals are a problem for us too! They are unstable of oily fish a week (FSA, 2004). Indeed, fish is so unpopular molecules generated by normal bodily functions, cigarette that the FSA admits that seven out of 10 people in the UK smoke, pollution, ultraviolet light and stress. Free radicals don’t eat any oily fish at all. Clearly then, oily fish is not a are linked to cancer or other diseases as well as the aging significant contributor of omega-3 fatty acids in the diets of process. Animals and plants protect themselves against free many people. radicals with antioxidants. They are a natural self-defence mechanism which is thought to defend against many From a public health perspective, encouraging people to diseases in humans, including the UK’s biggest killers heart eat more fish in order to gain healthy amounts of omega-3 disease and cancer. fats is simply not working. Even if people did start to consume more, the oceans simply cannot cope with any As stated, the three amigos of the antioxidant world more demand, and as we have seen, farmed fish is definitely are beta-carotene (vitamin A), vitamin C and vitamin E. not the solution. The mineral selenium is another valuable antioxidant. Antioxidants are not found abundantly in meat or fish. Plant The upshot of all this confusion and dislike for fish is that foods (including fruit, vegetables, nuts and seeds) are the many people fail to understand the importance of omega- best sources. In the largest, most comprehensive analysis 3s and do not realise how easy it is to obtain them from to date of the antioxidant content of commonly consumed every-day plant foods. Promoting oily fish as the only ‘heart foods cranberries, blueberries and blackberries ranked friendly’ solution could actually deter individuals from highest among the fruits studied. Beans, artichokes and making the fundamental dietary changes necessary for real Russet potatoes topped the list of vegetables. Pecans, long-term heart and body health. A healthier and simpler walnuts and hazelnuts were the top nuts and ground cloves, solution would be to promote a plant-based diet containing cinnamon and oregano ranked highest among the herbs EFA-rich seeds, nuts and oils. Plants, not fish, are the way and spices (Wu et al., 2004). As a general rule, brightly forward for good health. coloured vegetables (such as sweet potatoes, red cabbage and tomatoes) tend to be relatively high in antioxidants. Again, vegans are in a win-win situation. Not only do they Plant EFAs leading the way to good health avoid harmful substances found in meat and fish, they also benefit from a wide range of healthy nutrients including The good news is you don’t have to eat neurotoxins and fibre, vitamins, minerals and of course, antioxidants. carcinogens to get your omega-3 fatty acids; there are perfectly safe plant sources that can benefit your health. Antioxidants in plants protect EFAs Sustainability The antioxidant vitamins C, E and beta-carotene (the precursor of vitamin A) are found in abundance in plant The widely publicised supposed health benefits of omega-3 foods such as fresh fruits, vegetables, nuts and seeds. They fats from fish, together with dwindling supplies of fish are thought to be one of the body’s main defences against caught from the wild, have spawned a dramatic expansion damaging molecules called free radicals. They are also vital in aquaculture (farmed fish). Aquaculture has increased at for another important function that demonstrates why plant an annual rate of 9.2 per cent compared with 1.4 per cent for sources of fatty acids are superior to fish-derived versions. caught fish (Weaver et al., 2008). Most people (especially those who cook a lot) know Nearly half the fish consumed as food worldwide (43 per that certain fats are more likely to ‘go off’ when they are cent) is raised on fish farms rather than caught in the wild; exposed to air. The difference arises from the number of that’s up from just nine per cent in 1980 (FAO, 2006). The double bonds in the fat as they make fats vulnerable to level of fish caught in the wild (around 90-93 million tonnes attack from oxygen molecules. This is why we cover food annually) by contrast, has not changed much despite with plastic wrap or submerge it in water to protect it. growing world population and demand. It can’t. The FAO This is why fish oils are prone to oxidation and give off a acknowledges that there is little chance of any significant characteristic ‘fishy’ smell. increase in catches beyond these levels anyway. Antioxidants help slow this decaying process by acting The levelling off of wild catches coupled with the growing as a fall guy for the fatty acid; they take the oxygen hit world population and increasing demand for fish spells and save the fat from oxidative damage. Plant sources of trouble says the FAO. It estimates that an additional 40
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    28 The Fish Report: Why Public Health Policy Should Promote Plant Omega-3 in Preference to Fish Oils million tonnes of aquatic food will be required by 2030 just ■ Cut down on cholesterol (avoid eggs, meat and to maintain current levels of consumption. This is clearly dairy products) unsustainable, we have to look to alternatives, and fish farming is not the answer. The environmental problems such ■ Avoid or cut down on processed foods, trans fats from as the spread of disease, sea lice and pollution associated margarines and hydrogenated vegetable oils with farmed fish are abundant. The sensible, and in fact the only answer is to obtain our omega-3 fats from sustainable ■ Avoid or reduce fried foods, alcohol, caffeine, sugar, plant sources. smoking and stress For more information on the environmental impact of fishing see Viva!’s guide The End of the Line. Conclusion No short cuts, no magic bullet... Recommendations Fish is not a health food. Neither is it a magical wonder food that can guarantee good heart health and turn all kids into A well-balanced plant-based diet containing green leafy geniuses. The real problem here is not just the lack of good vegetables, wholegrain foods, pulses, nuts and seeds will fats in the diet; it’s the generally appalling state of most ensure an adequate intake of the plant omega-3 ALA. people’s diets. Fish is not a popular food; on average people One of the best sources is flaxseed oil, containing 57 per in the UK eat only a third of a portion of oily fish per week cent ALA and 16 per cent LA with a omega-6:omega-3 with seven out of ten people consuming none whatsoever. ratio of 0.28:1 (Davis and Kris-Etherton, 2003). A 14 gram We should stop looking for a ‘quick miracle fix’ and focus on tablespoonful of flaxseed oil provides eight grams of ALA. the bigger picture… improving our diets by cutting out the Flaxseed oil must be kept in the fridge and added to sauces saturated fatty foods laden with animal fats, sugar, salt and and dips or cooked food. Cooking with it will destroy its cholesterol and eating more fruit, vegetables, pulses, whole beneficial properties. In addition to this, try to buy and store grains, nuts and seeds. nuts, seeds and their oils in small quantities to ensure that they are as fresh as possible and limit the amount of time This report explains what the current research shows: fish the oils have to degrade. may be a source of protective fats but they are not the only, nor the healthiest, source. Fish are also a source of unhealthy It is difficult to say exactly how much of a certain food and unnecessary saturated fat in the diet. Plant-derived should be consumed to optimise EFA intake as the fatty EFAs are a far superior source of good fats in the diet. acid content of foods varies. However, a sensible approach is to reduce consumption of omega-6 rich vegetable oils Environmental contamination of the oceans now means (substitute sunflower or corn oil for olive oil in cooking), that when you take a mouthful of fish you are also taking a while increasing omega-3 intake (found in flaxseed oil, mouthful of neurotoxins and carcinogens (mercury, PCBs walnuts and green leafy vegetables). Limiting or avoiding and dioxins). Some people might consider this game of commercial oil-based processed foods will also help Russian roulette worth the risk if the health benefits afforded improve the omega-6:omega-3 ratio. Consumption of from fish could not be gained elsewhere. However, the saturated fatty acids (and trans fatty acids in processed research clearly shows that ALA from plants can protect foods) should also be limited as they are unnecessary in the heart health and doesn’t come laced with poison. Plant- diet, are a risk factor for atherosclerosis and can interfere derived EFAs have numerous advantages over fish-derived with the conversion of ALA into the longer chain omega-3s. fats yet are virtually ignored by health professionals. This may be due to the paucity of relevant research. The VVF is ■ To improve the conversion of ALA to EPA and DHA trying to address this by pushing for more research including follow these simple guidelines: plant-derived ALA alongside the fish oils EPA and/or DHA. ■ Consume a wide range of wholefoods everyday – Including fish in the typical Western diet, high in saturated remember variety is the spice of life! and processed fat, will not provide the health benefits that many people seek. A far more effective way to achieve good ■ Obtain most fat from whole foods (nuts, seeds, health is to adopt a more plant-based diet low in saturated wholegrains, olives, avocados and soya) fat and cholesterol but containing a healthy amount of polyunsaturated EFAs. Well-balanced vegetarian and ■ Select monounsaturated fat (olive oil) for cooking vegan diets, containing EFA-rich foods, not only help combat heart disease but also protect against many other ■ Use omega-6 fats (sunflower oil, safflower oil) with degenerative diseases. moderation Although the main focus of this report is human health, ■ Use omega-3 fat (flaxseed oil) for salad dressing and in the environmental argument for switching to plant-based dips but do not cook with it (store it in the fridge) omega-3s cannot be ignored. We know how commercial
  • 29.
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    About the Vegetarian& Vegan Foundation The Vegetarian & Vegan Foundation (VVF) is a science-based health and nutrition charity which monitors and interprets the growing body of research linking diet and health. The VVF helps the public, health professionals and the food industry make informed choices about diet by providing accurate information and advice about healthy eating. The VVF also runs health and education campaigns, presents school talks, cookery demonstrations, produces a magazine, VeggieHealth, and a wide variety of materials, runs the Vegetarian Recipe Club and answers nutritional queries from the public. The majority of diseases that kill most of us prematurely can be prevented by consuming a plant-based diet – the VVF explains why and provides information and advice about healthy eating. ISBN: 978-0-9557653-4-6