2. Perspectives in Nutrition 5 th ed. Gordon M.Wardlaw, PhD, RD, LD, CNSD PowerPoint Presentation by Dana Wu Wassmer, MS, RD

3. Chapter 5: Carbohydrates

4. Monosaccharides (Fig. 5-1) Structure Glucose Fructose Galactose Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

5. Fructose Metabolized to glucose in the liver Metabolized to glycogen Metabolized to lactic acid Found in fruit, honey, and high fructose corn syrup

6. Galactose Usually bound with glucose (lactose) Converted to glucose in the liver Available fuel source

7. Disaccharides Glycosidic bond Condensation reaction Alpha glycosidic bond Beta glycosidic bond Maltose (Gluc + Gluc) --alpha bond Sucrose (Gluc + Fruc) --alpha bond Lactose (Galactose + Gluc) --beta bond

8. Complex carbohydrates Oligosaccharides: raffinose & stachyose Polysaccharides: Starch & Glycogen Dietary fiber

9. Oligosaccharides 3-10 monosaccharides Found in beans and legumes Not digested Metabolized by bacteria in the large intestine Beno®

10. Polysaccharides: Starch 3,000 or more monosaccharides bound together Starch--alpha glycosidic bond –Amylose--straight chain polymer –Amylopectin--highly branched polymer Modified food starch and gel formation

11. Polysaccharide: Glycogen Storage form of CHO for animals and human Structure similar to amylopectin More sites for enzyme action Found in the liver and muscles

12. Dietary Fiber Undigested plant food Beta glycosidic bond Insoluble fiber –Cellulos, hemicellulose, lignin –Not fermented by the bacteria in the colon Soluble fiber –Gum, Pectin, Mucilage –Fruit, vegetable, rice bran, psyllium seed

13. Soluble and Insoluble Fiber (Fig. 5-4) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

14. Bacterial Metabolism of Soluble Fiber Short-chain fatty acids Enhance the health of the large intestine cells Fuel source Absorbed into the blood stream Yields kcal

15. Digestion of Carbohydrate in the Mouth Saliva contains amylase Starch is broken down to dextrins and maltose Taste the sweetness with prolong chewing

16. Digestion of Carbohydrate in the Stomach The acidic environment stops action of salivary amylase No further starch digestion occurs

17. Digestion of carbohydrate in the small intestine Pancreatic amylase is released Intestinal cells release maltase, sucrase, and lactase Maltose + maltase glucose + glucose Sucrose + sucrase glucose + fructose Lactose + lactase glucose + galactose Monosaccharides are absorbed

18. CHO Digestion (Fig. 5-5) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

19. CHO Absorption Glucose and Galactose Active absorption using a sodium pump Energy is expended to pump the sodium back out of the cell Going from low concentration gradient to high Fructose Facilitated diffusion using a carrier No energy expended

20. Active Absorption (Fig. 5-6) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

21. Portal Vein Transport absorbed monosaccarhides Delivers them to the liver Liver can: transform them to glucose release them back to the blood stream store as gylcogen (or fat)

22. Functions of Carbohydrate Supplies energy Protein sparing Prevent ketosis Sweetener

23. Health Benefits of Dietary Fiber Promotes softer, larger stool and regularity Slows glucose absorption Reduces blood cholesterol Reduces heart disease Reduces hemorrhoids and diverticula

24. Diverticula (Fig. 5-7) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

25. Recommended CHO Intake No RDA set 50-100 gm of CHO/day to prevent ketosis Reasonable goal: 45% of total kcals from starch; 55-60% from total CHO Current intake 200-300 gm of CHO/day (primarily from white bread, sodas, baked goods) 50% of total kcals

26. Recommended Dietary Fiber Intake 20-35 gm of fiber/day (10-13 gm/1000 kcals) Children: age +5gm/day Ave. U.S. intake: ~16 gm/day Too much fiber (>60 gm/d) will: –require extra intake of fluid –bind to some minerals –develop phytobezoars –fills the stomach of a young child quickly

27. Recommendation for Simple Sugar Intake Low nutrient density Recommends no more than 10% of total kcal/day Ave. U.S. intake: 16% of total kcal/day Added to food and beverages during processing

28. High Sugar Diets Empty calories Soda replacing milk Calories adding to excess Dental caries –exposure to teeth High glycemic index –Blood glucose response of a given food –Influence by various factors

29. Effect of High GI CHO Stimulates the release of insulin Insulin effect blood triglycerides level Insulin effect LDL Insulin increase fat synthesis Return to hunger quicker Muscle may become resistant to the insulin

30. Lactose Intolerance Reduction in lactase –Lactose is undigested and not absorbed –Lactose is metabolized by large intestinal bacteria causes gas, bloating, cramping, discomfort Primary lactose intolerance disease Secondary lactose intolerance disease

31. What To Do If You Are Lactose Intolerance Determine tolerated amount you can tolerate Eat dairy with fat Cheese is usually tolerated well Yogurt is usually tolerated well Use of Lact-Aide

32. Sweeteners Sucrose--benchmark of all sweeteners Same caloric content (4 kcals/gm) No health benefit over another

33. Types of Sweeteners High-fructose corn syrup –cornstarch treated with acid and enzymes –conversion of glucose into fructose –same degree of sweetness as sucrose –cheaper and used in many food products Brown sugar Maple syrup Honey Sugar alcohols –1.5-3 kcal/g –Absorbed and metabolized slower –Large amounts causes diarrhea

34. Sugar Substitutes Saccharin 180-200x sweeter than sucrose Excessive intake is linked to bladder cancer in lab animals Not a potential risk in humans

35. Aspartame (NutraSweet) Composed of phenylalanine, aspartic acid, and methanol 180-200x sweeter than sucrose 4 kcal/gm, but only a trace amount is needed to sweeten foods Not heat stable Complaints of sensitivity to aspartame –headaches, dizziness, seizures, nausea, etc. Not recommended for people with phenylketonuria (PKU)

36. Acesulfame-k (Sunette) Newest sugar substitute 200x sweeter than sucrose Not digested by the body Heat stable Diabetisweet used in baking

37. Other Sugar Substitutes Altiame -2000x sweeter Sucralose (Splenda)- 600 x sweeter D-Tagatose- same sweetness, but half the calories Stevia - 100-300 x sweeter, 0 kcal Thaumatins - 2000 x sweeter

38. Regulation of Blood Glucose Hyperglycemia Hypoglycemia

39. Blood Glucose Control Role of the liver –Regulates glucose that enters bloodstream Role of the pancreas –Release of insulin –Release of glucagon Maintain Homeostasis

40. Functions of Insulin Promotes glycogen synthesis Increases glucose uptake by the cells Reduces gluconeogenesis Net effect: lowers the blood glucose

41. Functions of Glucagon Breakdown glycogen Enhances gluconeogenesis Net effect: raises blood glucose

42. Other Hormonal Influence Epinephrine/norepinephrine –“fight or flight” response –breakdown glycogen –raises blood glucose Cortisol and growth hormone –increase gluconeogenesis –raises blood glucose

43. Factors in Glucose Control (Fig. 5-11) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

44. Diabetes Mellitus--Type 1 Genetic link Decreased release of insulin Insulin dependent Resulting in hyperglycemia Immunological disorder Early introduction of cow’s milk

45. Treatment for Type 1 CHO counting Insulin therapy Risk for heart disease

46. Diabetes Mellitus--Type 2 Genetic link Associated with obesity Non-insulin dependent to start Accounts for majority of cases of DM Defective insulin receptors on the cells Over secretion of insulin to compensate Leads to beta cells failure Treatment: medication and diet therapy (weight loss)

47. Consequences of Uncontrolled Blood Glucose Ketosis leading to ion imbalances, dehydration, coma, death Degenerative diseases –Nerve damage, Heart disease, Kidney disease, Blindness Atherosclerosis Increase risk for wound infections

48. Glycemic Index A ratio used to measure the amount of glucose appearing in the blood after eating a specific food compared to eating white bread Considers: –dietary fiber content of the food –digestion rate of the body –total fat content of the food

49. Hypoglycemia Reactive hypoglycemia –Occurs 2-4 hours after eating a meal –Possibly due to over secretion of insulin Fasting hypoglycemia –Usually caused by pancreatic cancer –Leads to overproduction of insulin