Chapter 4 Carbohydrates: Sugar, Starch, Glycogen, and Fiber

1. Chapter 4 Carbohydrates: Sugar, Starch, Glycogen, and Fiber Nutrition: Concepts & Controversies, 12e Sizer/Whitney

2. Learning Objectives • Describe the major types of carbohydrates, and identify their food sources. • Describe the various roles of carbohydrates in the body, and explain why avoiding dietary carbohydrates may be ill-advised. • Summarize how fiber differs from other carbohydrates and how fiber may contribute to health.

3. Learning Objectives • Describe the scope of the U.S. diabetes problem and educate someone about the long- and short-term effects of untreated diabetes and prediabetes. • Name components of a lifestyle plan to effectively control blood glucose and describe the characteristics of a diet that can assist in managing type 2 diabetes.

4. Carbohydrates • Ideal nutrients • Energy needs • Feed brain and nervous system • Keep digestive system fit • Keep your body lean • Digestible and indigestible carbohydrates • Complex vs. simple carbohydrates

5. A Close Look at Carbohydrates • Contain the sun’s radiant energy • Green plants • Photosynthesis • Glucose • Plants do not use all of the energy stored in their sugars • Carbohydrate-rich foods • Plants • Milk

6. Carbohydrate – Mainly Glucose – Is Made by Photosynthesis

7. A Close Look at Carbohydrates - Sugars • Six sugar molecules • Monosaccharides • Glucose, fructose, galactose • Disaccharides • Lactose, maltose, and sucrose • Digestion of mono- and disaccharides • Chemical names end in -ose

8. How Monosaccharides Join to Form Disaccharides

9. A Close Look at Carbohydrates – Starch • Polysaccharides • Starch • Plant’s storage form of glucose • Glycogen • Fiber • Nutrition • For a plant • For a human

10. How Glucose Molecules Join to Form Polysaccharides

11. A Close Look at Carbohydrates – Glycogen • Storage form of glucose • Animal bodies • Chains are longer than starch • More highly branched • Undetectable in meats

12. A Close Look at Carbohydrates - Fibers • Human digestive enzymes cannot break bonds • Bacteria in large intestine • Fermentation • Soluble vs. insoluble fibers

13. The Need for Carbohydrates • Critical energy source • Nerve cells and brain • Preferred dietary sources • Starchy whole foods • Complex carbohydrates • Vital roles in the functioning body

14. The Need for Carbohydrates • Weight loss • Caloric contribution • Conversion into fat storage • Refined sugars • Increase fiber-rich whole foods • Reduce refined white flour and added sugars

15. Characteristics, Sources, and Health Effects of Fibers

16. Fiber Composition of Common Foods

17. Why Do Nutrition Experts Recommend Fiber-Rich Foods? • Lower cholesterol and heart disease risk • Complex carbohydrates • More than just fiber • Viscous fiber • Cholesterol synthesis • Blood glucose control • Whole grains • Soluble fibers

18. One Way Fiber in Food May Lower Cholesterol in the Blood

19. Why Do Nutrition Experts Recommend Fiber-Rich Foods? • Maintenance of digestive tract health • All kinds of fiber • Ample fluid intake • Benefits of fiber • Constipation, hemorrhoids, appendicitis, diverticulosis

20. Diverticula

21. Why Do Nutrition Experts Recommend Fiber-Rich Foods? • Digestive tract cancer and inflammation • Ways fiber works against cancer • Dilution • Folate • Resident bacteria • Butyrate • Recommended dietary sources • Healthy weight management • Appetite control

22. Fiber Recommendations and Intakes • Few people in U.S. meet recommendations • 20-35 grams of fiber daily • Based on energy needs, age, and gender • Adding fiber to diet • Too much fiber? • Dangers of excess • Binders in fiber • Chelating agents • Cause of deficiencies

23. Usefulness of Carbohydrates

24. Refined, Enriched, and Whole-Grain Foods • Bread supplies much carbohydrate for many people • Kernel (whole grain) has four main parts • Germ • Endosperm • Bran • Husk

25. Refined, Enriched, and Whole-Grain Foods • U.S. Enrichment Act of 1942 • Required additives • Addition in 1996 • Advantages of whole grains vs. enriched grains • Finding the whole grains in foods

26. Bread Labels Compared

27. From Carbohydrates to Glucose – Digestion & Absorption • Starch and disaccharides are broken down • Monosaccharides for absorption • Starch • Begins in the mouth • Splits starch into maltose • Digestion ceases in the stomach • Digestion resumes in small intestine • Pancreas • Resistant starch

28. How Carbohydrate in Food Becomes Glucose in the Body

29. Why Do Some People Have Trouble Digesting Milk? • Ability to digest milk carbohydrates varies • Lactase • Made by small intestine • Symptoms of intolerance • Nausea, pain, diarrhea, and gas • Milk allergy • Nutritional consequences • Milk tolerance and strategies

30. The Body’s Use of Glucose • Basic carbohydrate unit used for energy • Body handles glucose judiciously • Maintains an internal supply • Tightly controlling blood glucose concentrations • Brain, nervous system, red blood cells

31. Splitting Glucose for Energy • Glucose is broken in half • Can reassemble • Broken into smaller molecules • Irreversible • Two pathways

32. Splitting Glucose for Energy • Glucose can be converted to fat • Fat cannot be converted to glucose • Dependence on protein when insufficient carbohydrate • Protein-sparing action • Ketosis • Shift in body’s metabolism • Disruption of acid-base balance • DRI minimum of digestible carbohydrate

33. How Is Glucose Regulated in the Body? • Two safeguard activities • Siphoning off excess blood glucose • Replenishing diminished glucose • Two hormones • Insulin • Signals body tissues to take up glucose • Glucagon • Triggers breakdown of glycogen • Epinephrine

34. Handling Excess Glucose • Body tissue shift • Burn more glucose • Fat is left to circulate and be stored • Carbohydrate storage as fat • Liver breakdown and assembly • Costs a lot of energy • Weight maintenance • Dietary importance and composition

35. Glycemic Index of Food • Elevation of blood glucose and insulin • Food score compared to standard food • Diabetes • Glycemic load (GL) • Lower GL = less glucose guild up and less insulin needed • Limitations of glycemic index • Resist notion of “good” or “bad” foods

36. Glycemic Index of Selected Foods

37. Diabetes • Prevalence of diabetes • Adults • Children • Prediabetes • Importance of testing • Perils of diabetes • Toxic effects of excess glucose • Inflammation • Circulation problems

38. Prevalence of Diabetes Among Adults in the United States

39. Type 1 and 2 Diabetes Compared

40. An Obesity-Diabetes Cycle

41. Accusation 1: Carbohydrates Are Making Us Fat • Americans are fatter • Greater consumption of calories • 300-500 per day • Epidemiological studies • Weight loss

42. Percentage of Calories from Energy Nutrients, U.S., 1977-2006

43. Accusation 4: High-Fructose Corn Syrup Harms Health • Villainy has been exaggerated • Nature of HFCS • Half of added sugar in U.S. food supply • Obesity • HCFS not a proven cause • Liquid sugar and calorie control • Appetite regulation • Fructose does not stimulate insulin release

44. Accusation 4: High-Fructose Corn Syrup Harms Health • Effects on lipid metabolism • Fructose causes fats to accumulate in blood and liver • Metabolic activities of concern