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Carbohydrates

Carbohydrates. Carbohydrates. Body’s preferred energy source Human brain uses it exclusively 2 categories simple complex Found in plants and dairy products. Carbohydrates. Simple sugars monosaccharides disaccharides sweet Complex sugars polysaccharides not sweet. Monosaccharides.

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Carbohydrates

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  1. Carbohydrates

  2. Carbohydrates • Body’s preferred energy source • Human brain uses it exclusively • 2 categories • simple • complex • Found in plants and dairy products

  3. Carbohydrates • Simple sugars • monosaccharides • disaccharides • sweet • Complex sugars • polysaccharides • not sweet

  4. Monosaccharides Disaccharides Sucrose Glucose Lactose Fructose Maltose Galactose Found only as part of lactose

  5. Monosaccharides • Absorbed directly into blood stream without digestion • Glucose (plant sugar) - 4 kcal/g • from starch digestion or hydrolysis • Other forms of CHO are converted into glucose - needs insulin for take up • Dextrose- monohydrate of glucose • used in IVF (3.4 kcal/g)

  6. Monosaccharides • Fructose- fruit and honey • Sweetest of all sugars • Used almost exclusively in soft drinks • Can be used in very small amounts to hide after taste in diet drinks

  7. Monosaccharides • Galactose • Appears in nature only as part of lactose “milk sugar” • Changed to glucose for energy • Reaction is reversible • During lactation glucose reconverted to galactose for use in milk production

  8. Monosaccharides • Compounds used in medications • Cardiac glycosides - digitalis • Steroids • Antibiotics - streptomycin, erythromycin • Deoxy sugars - DNA

  9. Monosaccharides • Derivatives- sugar ETOH • Sorbitol side effects: diarrhea, gas, abdominal discomfort • Helps with dental caries • Sorbitol occurs naturally in prunes, apple juice, etc. • Liquid medications

  10. Monosaccharides Disaccharides Sucrose Glucose Lactose Fructose Maltose Galactose Found only as part of lactose

  11. Disaccharides • Maltose = glucose and glucose • Plant sugar found in germinating cereal grains • Used in some infant formulas and cereals • Highly significant in human nutrition as intermediate product of starch digestion

  12. Disaccharides • Pairs of simple sugars linked together • Sucrose = glucose and fructose • Sugar beets, sugarcane, molasses, maple syrup • Fructose converts to glucose in body • 7-11% total kcal in American diet • NO difference between honey and sugar

  13. Disaccharides • Lactose=glucose and galactose • Principle CHO of milk • Lactose intolerance common -no lactase or digestive enzyme in digestive system -can be transient after illness

  14. Polysaccharides • Starch, glycogen, dextrin, dietary fiber • Starch- hundreds of linked glucose units • Amylopectin and amylose-ratios and structures differ • ~80-85% amylopectin- insoluble • ~15-20% amylose-soluble

  15. Starch Cellulose

  16. Polysaccharides • Amlyopectin- thickening agent • Amylose - slow even rate of digestion • Amylase-digestive enzyme • Cereal grains, legumes, potatoes • Dextrin-intermediate product from breakdown of starch-makes maltose

  17. Glycogen • Stored energy • Found in liver and muscle tissue • Important link in energy metabolism • Sustains normal blood sugars during fasting

  18. Oligosaccharides • Small portions of partially digested starches (3-10 monosaccharides) • Infant formulas • Special dietary formulas • Sports drinks • Faster and easier to digest

  19. Dietary fiber • Soluble and insoluble • Celluloses, pectins, mucilages, gums, lignin • Need 20-35 grams/day • Have laxative effect, soften stools • Increase transit time, influence blood lipid levels

  20. Dietary fiber • Increase satiety • Bulk helps with weight control, constipation, diverticulosis • Undesirable effects- binds Fe++, Ca++, & Zn++ • Produce colon bacteria-volatile short chained fatty acids/GAS

  21. Insoluble-Cellulose & Lignin • Cellulose-not digestible • has no nutrients • produces bulk • grains, fruits, vegetables • Lignin is non-carbohydrate fiber • binds bile acids and metals • whole grain, strawberries, mature vegetables

  22. Insoluble • Soften stools • Regulates bowel movements • Increase fecal weight • Increase transit time • Reduce risks of diverticulosis, hemorrhoids, and appendicitis

  23. Non-cellulose fiber • Soluble-Absorbs water • Slows gastric emptying • Binds bile acids • Adds some bulk • Found in • pectin • gums • mucilage

  24. Carbohydrate Digestion • Polysaccharides are broken down to • Disaccharides are broken down to • Monosacharides which are absorbed through intestinal mucosa and transported to the liver

  25. Carbohydrate Metabolism • In the liver: • Fructose and Galactose converted to Glucose • Blood sugars rise • Insulin secreted • Insulin moves glucose out to bloodstream and into cells

  26. Carbohydrate Metabolism • Muscle cells convert glucose to glycogen if storage CHO is needed. • IF energy needed, glucose is burned in cells. • Glucose not needed for energy or glycogen is used to make DNA, RNA, or converted to fatty acids and stored as triglycerides.

  27. Carbohydrate Function • Provides energy-especially to brain, nervous system, used by muscles • 4 kcalories per gram • Spares protein • Prevents ketosis • Quickly digested-principle site is small intestine

  28. Glycogen • Immediate fuel for muscle actions • 1200-1500 kcal on board • 2/3 stored in muscle/ 1/3 in liver • 2.7- 3.4 g of water stored with every gram of glycogen

  29. Glycogen • Minimum of 100g CHO/ day to prime citric acid cycle to prevent keto-acidosis to prevent excessive tissue protein breakdown • Symptoms from lack of CHO : fatigue, dehydration

  30. Healthy Diet • CHO 50-60% of daily diet • 10% of this amount should be sweets • Fiber intake 20-35 grams/day • CHO alone does not cause obesity • remember fat and activity levels

  31. Chronic Diseases • Diabetes-Type 2 related to body fatness • 95% of DM are Type 2 • Heart Disease-fat not sugars • Sugar behavior-unproven

  32. Nutrients in 100 Kcalories Food Protein Calcium • Sugar (2T) 0 g trace • Cola (1 C) 0 g 6 mg • Milk (1 c) 8 g 300 mg • Bread ( 1 slice) 3 g 48 mg • Pinto Beans (1/2 c) 7 g 41 mg

  33. Sugar Alcohols • Used in chewing gums • 2-3 kcal per gram • Examples: • Sorbitol • Isomalt • Xylitol

  34. Artificial Sweeteners • Saccharin-pros and cons • Aspartame-Equal • Acesulfame K- Sunette & Sweet One • Sucralose-Splenda • Use as replacement, not addition, if used for weight control

  35. Glycemic Response • Effect of a particular food on blood glucose reduced to a number • Factors: • Amount of fat and fiber • Method of preparation • Amount eaten • Use for fine tuning meal planning with DM patients and athletes

  36. GI Food Pyramid Refined Grains Potatoes Sweets Unrefined Grains Pasta Dairy Lean Protein Nuts Legumes Fruits Vegetables

  37. Fat & Energy • Used to meet 50% of energy needs • Most cells can utilize fat for energy • Not brain cells or nerves • Fat cannot be converted to glucose

  38. Ketosis? • Ketone bodies • Acidic, fat related compounds formed from incomplete breakdown of fat when no carbohydrate is available.

  39. Protein and Energy • Protein used for energy when • glycogen depleted • Body starts to auto-digest • CHO has protein sparing effect

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