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Chapter4
- 1. TheThe Carbohydrates:Carbohydrates: Sugars, Starches,Sugars, Starches, andFibersand Fibers Chapter 4Chapter 4
- 2. IntroductionIntroduction • Brain • Glucose •Muscles • Glucose • Glycogen • Fat • Sources of carbohydrates • “Fattening” – mistaken thinking
- 3. ChemistChemist’s View of’sView of CarbohydratesCarbohydrates • Carbohydrate family • Atoms and chemical bonds • Monosaccharides • Chemical shorthand • Glucose, fructose, galactose • Disaccharides • Maltose, sucrose, lactose • Polysaccharides
- 4. Atoms and TheirBondsAtoms and Their Bonds
- 5. ChemistChemist’s View of’sView of CarbohydratesCarbohydrates • Monosaccharides – three • Same numbers and kinds of atoms • Differing sweetness • Glucose – blood sugar • Part of every disaccharide • Fructose • Sweetest of the sugars • Galactose • Only in a few foods
- 6. Chemical Structure ofGlucose
- 7.
- 8. ChemistChemist’s View of’sView of CarbohydratesCarbohydrates • Disaccharides • Pairs of three monosaccharides • Maltose – two glucose units • Sucrose – glucose and fructose • Lactose – galactose and glucose • Condensation • Links two monosaccharides together • Hydrolysis • Breaks a disaccharide in two
- 9. Condensation and HydrolysisCondensationand Hydrolysis of a Disaccharideof a Disaccharide
- 10. ChemistChemist’s View of’sView of CarbohydratesCarbohydrates • Polysaccharides • Glycogen • Storage form of energy in the body • Glucose units • Starch • Storage form of energy in plants • Glucose units
- 11.
- 12. ChemistChemist’s View of’sView of CarbohydratesCarbohydrates • Polysaccharides • Fibers • Differ from starches • Soluble fibers – benefits • Insoluble fibers – benefits • Functional fibers • Resistant starches • Phytic acid
- 13. The Bonds ofStarch and Cellulose Compared
- 14. Carbohydrate DigestionCarbohydrate Digestion •Ultimate goal • Glucose for absorption and use • Hydrolysis via enzymes • Mouth • Amylase • Stomach • Stomach acid & protein-digesting enzymes • Role of fiber
- 15. Carbohydrate DigestionCarbohydrate Digestion •Small intestine • Most carbohydrate digestion • Pancreatic amylase • Specific disaccharide enzymes • Maltase • Sucrase • Lactase • Large intestine • Fibers
- 16. Carbohydrate AbsorptionCarbohydrate Absorption •Active transport • Glucose • Galactose • Facilitated diffusion • Fructose • Liver • Conversion of fructose and galactose
- 17.
- 18. Lactose IntoleranceLactose Intolerance •Lactase activity • Highest immediately after birth • Declines with age • Symptoms of intolerance • Causes of intolerance beyond age • Prevalence • Genetically determined
- 19. Lactose IntoleranceLactose Intolerance •Dietary changes • Manage dairy consumption rather than restriction • GI bacteria • Fermented milk products • Individualized diets • Potential nutrient deficiencies • Riboflavin, vitamin D, and calcium
- 20. Carbohydrate MetabolismCarbohydrate Metabolism •Glucose is key player • Storing glucose as glycogen • Liver storage • Condensation into glycogen • Hydrolysis for release of glucose when needed • Muscle storage • Selfishly hoards glycogen
- 21. Carbohydrate MetabolismCarbohydrate Metabolism •Glucose for energy • Fuels most of body’s cells • Preferred source for brain, nerve cells, and developing red blood cells • Cellular breakdown of glucose • Making glucose from protein • Amino acid conversion • Gluconeogenesis
- 22. Carbohydrate MetabolismCarbohydrate Metabolism •Ketone bodies from fat fragments • Inadequate supply of carbohydrates • Fat metabolism shifts • Ketone body formation – starvation • Ketosis – acid-base balance • Carbohydrate needs for protein sparing and prevention of ketosis • Using glucose to make fat
- 23. The Constancy ofBloodThe Constancy of Blood GlucoseGlucose • Steady supply in blood stream • Intestines – food • Liver – glycogen • Blood glucose homeostasis • Insulin • Glucose from blood into cells • Glucagon & epinephrine • Brings glucose out from storage
- 24. Maintaining Blood GlucoseMaintainingBlood Glucose HomeostasisHomeostasis
- 25. The Constancy ofBloodThe Constancy of Blood GlucoseGlucose • Balancing within the normal range • Balanced meals at regular intervals • Diabetes • Insulin is either inadequate or ineffective • Type 1 diabetes • Type 2 diabetes • Hypoglycemia • Prevalence
- 26. The Constancy ofBloodThe Constancy of Blood GlucoseGlucose • Glycemic response • Speed of glucose absorption, level of blood glucose, and return to normal glucose levels • Low glycemic response • Desired • High glycemic response • Glycemic index • Benefits • Utility
- 27. Health Effects ofSugarsHealth Effects of Sugars • Pleasure in moderate amounts • Obesity and chronic disease • Nutrient deficiencies • Energy with few other nutrients • Discretionary kcalories • Honey • More energy per spoonful • Health benefits
- 28. Health Effects ofSugarsHealth Effects of Sugars • Dental caries • Bacteria ferment sugars producing acid • Food factors associated with tooth decay • Time of food in mouth • Sticky foods • Frequency of sugar consumption • Food choices • Factors associated with tooth decay
- 29. Recommended Intakes ofRecommendedIntakes of SugarsSugars • Dietary Guidelines • Reduce the intake of kcalories from added sugars • DRI • Added sugars • No more than 25% of day’s total energy • Impact on other food groups • WHO and FAO recommendations
- 30. Alternative SweetenersAlternative Sweeteners •Artificial sweeteners • Non-nutritive sweeteners • Large doses and adverse effects • Stevia – an herbal product • Generally recognized as safe (GRAS) • Sugar alcohols • Provide kcalories • Benefits and side effects
- 31. Health Effects ofStarch andHealth Effects of Starch and FibersFibers • Heart disease • Whole grains • Sources • Soluble fibers • Sources • Improving heart disease risk factors • Diet composition for reducing heart disease risk
- 32. Health Effects ofStarch andHealth Effects of Starch and FibersFibers • Diabetes • High-fiber foods • GI health • High-fiber foods • Ample fluids • Weight management • High-fiber foods and whole grains • Feeling of fullness
- 33. Health Effects ofStarch andHealth Effects of Starch and FibersFibers • Cancer • Dietary fiber and colon cancer • Fiber supplements • Sources of dietary fiber • Phytochemicals • Preventing colon cancer • Diluting, binding, and removing • Bacterial fermentation
- 34. Health Effects ofStarch andHealth Effects of Starch and FibersFibers • Excessive fiber • Insufficient energy or nutrient needs • Abdominal discomfort, gas, diarrhea • GI obstruction • Nutrient absorption • Dietary goals • Balance, moderation, variety
- 35. Characteristics, Sources, &Characteristics,Sources, & Health Effects of FibersHealth Effects of Fibers
- 36. Recommended Intakes ofRecommendedIntakes of Starch & FibersStarch & Fibers • DRI for carbohydrates • 45 to 65% of energy requirement • RDA for carbohydrates • 130 grams per day • Fiber • DV: 11.5 grams per 1000-kcalories • DRI: 14 grams per 1000-kcalories • No UL
- 37. From Guidelines toGroceriesFrom Guidelines to Groceries • Grains • 1 ounce provides about 15g of carbohydrate • “Three are key” message • Vegetables • Starch content • Fruits • Milk and milk products • Protein foods
- 38. From Guidelines toGroceriesFrom Guidelines to Groceries • Read food labels • Total carbohydrate • Starch, fibers, sugars • Sugars • Added and natural sugars
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- 40.
- 41. CarbohydratesCarbohydrates’ kCalorie’ kCalorie ContributionsContributions •Obesity and the link to carbohydrates • Total daily energy intakes have increased • Activity levels have declined • Increase in body weight • Epidemiological studies • Inverse relationship between carbs & weight • Weight loss • kCalorie intake
- 42.
- 43. Daily Energy Intake& Increases in Adult Body Weight over Time
- 44. SugarsSugars’ Share inthe Problem’ Share in the Problem • Increase in consumption of added sugars • High-fructose corn syrup • Body fat stores • Carbohydrate cravings • Self-imposed labeling of foods • Carbohydrate addictions • Not physiological or pharmacological
- 45. SugarsSugars’ Share inthe Problem’ Share in the Problem • Appetite control • Fructose and insulin • Flaws in plausibility • Food form – liquid or solid • Simple to swallow • Energy regulation
- 46. InsulinInsulin’s Response’s Response •Surge of insulin levels • Glycemic effect • Factors impacting glycemic effect • Glycemic index and body weight • Insulin resistance • Fructose • Prediabetes and metabolic syndrome • Body’s insulin response