1 / 49

Chapter 4: Carbohydrates

Chapter 4: Carbohydrates. Plants Synthesize Glucose. Structure Glucose Fructose Galactose. Monosaccharides. Fructose (fruit sugar). Metabolized to glucose in the liver Found in fruit, honey, and high fructose corn syrup Is in sucrose. Galactose. Usually bound with glucose (lactose)

ashanti
Download Presentation

Chapter 4: Carbohydrates

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 4: Carbohydrates

  2. Plants Synthesize Glucose

  3. Structure Glucose Fructose Galactose Monosaccharides

  4. Fructose (fruit sugar) • Metabolized to glucose in the liver • Found in fruit, honey, and high fructose corn syrup • Is in sucrose

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

  6. Disaccharides • “Simple sugars” • Maltose (Gluc + Gluc) • Fermentation • Alcohol production • Sucrose (Gluc + Fruc) • Sugar • Lactose (Galactose + Gluc) • Milk products

  7. Complex Carbohydrates • Polysaccharides: Starch & Glycogen • Amylose • Amylopectin • Dietary fiber

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

  9. Polysaccharides: Starch • 3,000 or more monosaccharides bound together • Starch • Amylose--straight chain polymer • Amylopectin--highly branched polymer

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

  11. Dietary Fiber • Undigested plant food • Body cannot break the bonds • Insoluble fiber • Cellulos, hemicellulose, lignin • Not fermented by the bacteria in the colon • Soluble fiber • Gum, Pectin, Mucilage • Fruit, vegetable, rice bran, psyllium seed

  12. Soluble and Insoluble Fiber

  13. Health Benefits of Dietary Fiber • Absorbs and holds water • Soften stool • Larger stool promotes peristalsis • Promotes regularity • Lower risk for cardiovascular disease • Decrease hemorrhoids and diverticula

  14. Diverticula

  15. CHO in Food

  16. Sweeteners • Sucrose--benchmark of all sweeteners • Same caloric content (4 kcals/gm) • No health benefit over another • Consumption ranges: 14-48 lbs/yr per person

  17. 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 amount causes diarrhea

  18. Sugar Substitutes • Saccharin • First produced in 1879 • 180-200x sweeter than sucrose • Excessive intake is linked to bladder cancer in lab animals • Not a potential risk in humans

  19. 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)

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

  21. Sucralose (Splenda) • 600x sweeter than sucrose • Substitute chlorines for hydroxyl groups on sucrose • Heat stable • Tiny amount digested

  22. Digestion

  23. Effects of Cooking • Softens fibrous tissues • Easier to chew and swallow

  24. Digestion of Carbohydrate in the Mouth • Saliva contains amylase • Starch is broken down to shorter saccharides • Taste the sweetness with prolong chewing • Proceeds down the esophagus

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

  26. In the Small Intestine • Pancreatic amylase is released • Intestinal cells release enzymes • Maltose + maltase glucose + glucose • Sucrose + sucrase glucose + fructose • Lactose + lactase glucose + galactose • Monosaccharides are absorbed

  27. CHO Digestion

  28. CHO Absorption • Glucose and Galactose • Active absorption • Energy is expended • Going from low to high concentration gradient • Fructose • Facilitated diffusion using a carrier • No energy expended

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

  30. Functions of Carbohydrate • Supplies energy • Protein sparing • Prevent ketosis • Sweetener

  31. Regulation of Blood Glucose • Hyperglycemia • Hypoglycemia

  32. Blood Glucose Control • Role of the liver • Regulates glucose that enters bloodstream • Role of the pancreas • Release of insulin • Release of glucagon

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

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

  35. Epinephrine/ Norepinephrine • “fight or flight” response • breakdown glycogen • raises blood glucose

  36. Diabetes Mellitus-Type 1 • Genetic link • Decreased release of insulin • Insulin dependent • Hyperglycemia • Immunological disorder • Early introduction of cow’s milk

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

  38. 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)

  39. 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

  40. 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

  41. Sweetener Function • Enhances flavor • Use in moderation

  42. Recommended Intake • No RDA (yet) • Consume at least 50 gm to prevent ketosis • National Cholesterol Education Program recommends 50-60% of kcal from CHO • Current intake is ~50%

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

  44. 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

  45. 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

  46. 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

  47. Effects of High Glycemic Index CHO • Stimulates the release of insulin • Insulin’s effect blood triglycerides level • Insulin’s effect LDL • Insulin increases fat synthesis • Return to hunger quicker • Develop insulin resistance

  48. 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

  49. What To Do If You Are Lactose Intolerance • Determine amount you can tolerate • Eat dairy with fat • Cheese & yogurt are usually tolerated well • Use of Lact-Aide

More Related