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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 • 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 Disaccharides Sucrose Glucose Lactose Fructose Maltose Galactose Found only as part of lactose
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)
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
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
Monosaccharides • Compounds used in medications • Cardiac glycosides - digitalis • Steroids • Antibiotics - streptomycin, erythromycin • Deoxy sugars - DNA
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
Monosaccharides Disaccharides Sucrose Glucose Lactose Fructose Maltose Galactose Found only as part of lactose
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
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
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
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
Starch Cellulose
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
Glycogen • Stored energy • Found in liver and muscle tissue • Important link in energy metabolism • Sustains normal blood sugars during fasting
Oligosaccharides • Small portions of partially digested starches (3-10 monosaccharides) • Infant formulas • Special dietary formulas • Sports drinks • Faster and easier to digest
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
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
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
Insoluble • Soften stools • Regulates bowel movements • Increase fecal weight • Increase transit time • Reduce risks of diverticulosis, hemorrhoids, and appendicitis
Non-cellulose fiber • Soluble-Absorbs water • Slows gastric emptying • Binds bile acids • Adds some bulk • Found in • pectin • gums • mucilage
Carbohydrate Digestion • Polysaccharides are broken down to • Disaccharides are broken down to • Monosacharides which are absorbed through intestinal mucosa and transported to the liver
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
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.
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
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
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
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
Chronic Diseases • Diabetes-Type 2 related to body fatness • 95% of DM are Type 2 • Heart Disease-fat not sugars • Sugar behavior-unproven
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
Sugar Alcohols • Used in chewing gums • 2-3 kcal per gram • Examples: • Sorbitol • Isomalt • Xylitol
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
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
GI Food Pyramid Refined Grains Potatoes Sweets Unrefined Grains Pasta Dairy Lean Protein Nuts Legumes Fruits Vegetables
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
Ketosis? • Ketone bodies • Acidic, fat related compounds formed from incomplete breakdown of fat when no carbohydrate is available.
Protein and Energy • Protein used for energy when • glycogen depleted • Body starts to auto-digest • CHO has protein sparing effect