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

Glucose Fructose Galactose Found only as part of lactose Sucrose Lactose Maltose

 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)

 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

 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

 Compounds used in medications  Cardiac glycosides - digitalis  Steroids  Antibiotics - streptomycin, erythromycin  Deoxy sugars - DNA

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

Glucose Fructose Galactose Found only as part of lactose Sucrose Lactose Maltose

 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

 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

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

 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

 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 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  kcal on board  2/3 stored in muscle/ 1/3 in liver  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 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 ProteinCalcium  Sugar (2T) 0 g trace  Cola (1 C) 0 g 6 mg  Milk (1 c) 8 g300 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