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Protein for Athletes American College of Sports Medicine (ACSM) / American Dietetic Association (ADA) –Endurance athletes, 1.2 to 1.4 g/kg per day • Accounts for greater use of protein as fuel for energy –Strength athletes, 1.2 to 1.7 g/kg per day • To support muscle growth, particularly during early training phase when gains are greatest and protein utilization is less efficient Clinical studies suggest there is no apparent benefit at intakes above 2.0 g/kg per day How much protein for athletes? • Many athletes may already meet or exceed protein recommendations – Definition of “high protein” can be the absolute amount of protein, % of total energy (calories), or protein ingested per kg of body weight • Strength athletes in particular may believe that much higher protein intakes are needed for muscle building – Intakes at 4- to 6-g/kg range are not uncommon – Unlikely to provide benefit beyond 2.0 g/kg – It is possible that this much protein intake could adversely affect the nutrient quality of the overall diet Risks of High Protein Hydration status – Nitrogen that is obtained from consuming protein must be excreted in the urine as urea – Increased urinary output due to high protein load may increase chances of dehydration Diets very high in protein may lack appropriate amounts of carbohydrate, fiber, and some vitamins/minerals – Could impair exercise performance – Could increase long-term risk of diseases such as colon cancer • Possibly due to lack of fiber or increased intake of red meat Excessively fatty protein sources could increase risk of cardiovascular disease – Choose mostly lean protein sources • For example, salmon is more desirable than a ribeye steak Branched Chain Amino Acids • Make up 40% of the daily requirements of essential amino acids Branched Chain Amino Acids BCAAs are Unlike other amino acids, most BCAA metabolism occurs in skeletal muscle – Liver lacks first 2 enzymes in the pathway that break down BCAAs Supplemental free form, bypass the liver and gut and go directly into the blood stream. BCAAs inhibit brains ability to uptake tryptophan Leucine – The bodies need for leucine is 25 times greater than the available free amino acid pool. – Stimulates protein synthesis by activating insulin – Insulin increases a.a. uptake – Incorporation of BCAAs in muscle is IGF-1 dependent – IGF-1 stimulates muscle synthesis – Chronic low levels of BCAAs will show up in urine – β-hydroxy-β-methylbutyrate (HMB) is derived from the breakdown of leucin – Some evidence in humans that doses of 3 g/day may be effective at preventing muscle breakdown • Additive benefits with creatine – Some studies suggest that HMB may provide greater benefit to untrained people who start weight training compared with previously conditioned athletes Should athletes Supplement? If protein requirements are met, the individual AA requirements should be met as well Estimated that 3-18% of workout energy is provided by BCAAs Leucine increases release of fats for energy Claims mainly center on decreasing muscle soreness and improving either performance or recovery from exercise Doses can range from 2 to 7 g/day to more than 20 g/day taken before during and after There are potential risks associated with AA supplements – Large doses of single AAs can prevent the absorption of other AAs, which may lead to diarrhea – Can indirectly cause deficiency of other AAs as a result Phosphocreatine • aka creatine phosphate (PCr) • Rapidly mobilizable reserve of high energy phosphate for skeletal muscle (and brain) • Formed from parts of Arg, Gly & Met • Can donate phosphate to ADP anaerobically in the first 2-7 seconds following an intense muscular effort • Forward and reverse reaction catalyzed by CK, which is a marker of muscle damage Alcohol • • • • Ethanol Not a nutrient 7 kcal/g 50% alcohol = 100 proof Alcohol Absorption • Small amounts absorbed in mouth and esophagus • 20% absorbed directly across stomach wall • Food delays diffusion • Most absorbed by simple diffusion in the upper small intestine • Distributed wherever water is found Alcohol metabolism 1) Alcohol Dehydrogenase System - women have less - varies among ethnic groups - NADH production turns of TCA cycle - Excess acetyl CoA converted to FATTY ACIDS - Fatty liver develops 2) Microsomal Ethanol-oxidizing System (MEOS) • • • • • When ADH cannot keep up with demand Occurs in liver, in cytosol of cells Also used to metabolize drugs and foreign substances Reduces bodies ability to detoxify drugs overdose Increases alcohol metabolism, thus tolerance leads to weight loss 3) Catalase Metabolism of Alcohol • Found in liver • Minor pathway for alcohol metabolism H2O2 Ethanol Catalase H2O Acetaldehyde Alcohol Metabolism • Depends on: - Sex - race - size - food - physical condition - alcohol content • Amount of alcohol dehydrogenase • Alcohol cannot be stored and has priority in metabolism Negative effects on vitamins and minerals • • • • • • • • • • Thiamin Niacin B6 B12 Folate Vitamin C Vitamin A Vitamin D Vitamin K Vitamin E • Magnesium • Zinc • Iron Alcoholics and malnutrition • • • • Poor diet Alcohol has energy but no nutrients Lack of interest in food: GI problems Alcohol interferes with absorption of amino acids • Alcohol races blood level of fats Liver Damage • Build up of acetaldehyde • Production of free radicals • Alcohol inhibits body’s natural antioxidant systems • Advanced stages of liver damage are not reversible Fetal Alcohol Syndrome • Alcohol reaches fetus • Deprives brain of oxygen and nutrients • About 4 drinks a day or binge drinking while pregnant • Prenatal and postnatal growth retardation • Brain and CNS impairment • Abnormalities of face and skull • increased rate of birth defects Health Benefits of Alcohol • Moderate drinking associated with reduced mortality • ≤ 2 drinks for men, ≤ 1 drink for femal • Reduced cardiovascular disease -reduces blood clotting -increase HDL -reduced inflammation • Polyphenols • Relaxation and socialization Fiber • Plant cell wall contains > 95% of dietary fibers - cellulose, hemicellulose, lignin, pectins -Lignin structural support -Pectin intercellular cement -Cereal bran hemicellulose and lignin -Fruit & Vegetables cellulose and pectin • Starch energy storage is found within the cells walls Fiber = ability to resist digestion in the small intestine Fiber Dietary + Functional = Total Fiber • Dietary – Found natuRally in foods • Functional – forms added to foods • Insoluble – Not fermented by bacteria in the colon • Soluble – Fermentable Fiber Soluble • • • • Pectin Gums Mucilages Some hemicellulose Insoluble • Lignin • Cellulose • Some hemicellulose Polysaccharides 1. Cellulose • Polysaccharide of glucose • Most abundant substance in plant kingdom • Β- 1,4 glycosidic linkages • Water insoluble • Does not provide energy • Bran, legumes, nuts peas, root vegetables, cabbage • Cotton is pure cellulose Insoluble fibers – Exterior/hulls & Structural 2. Hemi-cellulose • Mixture of pentoses & hexoses • Linked to lignin in cell wall • Amorphous • Partially soluble in mild alkali 3. Lignin • Highly branched • Not digested by colonic bacteria • Non-CHO • Structural support • Roots vegetables, carrots, wheat, fruits with seeds Soluble Fibers – inside & around plant 4. Pectin • gel forming • Amorphous • Intracellular cement – spaces b/w cell wall • Almost completely metabolized by colonic bacteria • Apples, strawberries & citrus • Added jellies & jams 5. Gums/Mucilages • Secreted at the site of plant injury: tree exudates • Highly branched • Highly fermented by colon bacteria • Gum arabic is a food additive for gelling • Caramels, gumdrops, toffee, bakery goods, salad dressings, oatmeal Physiological & Metabolic Effects Effects of Fiber 1. Solubility in water • delay gastric emptying • Increase transit time • Decrease nutrient absorption 2. Water-holding capacity • Delay gastric emptying • Reduced mixing of GI contents w/ digestive enzymes • Delayed nutrient absorption • Shortened transit time Physiological & Metabolic Effects Effects of Fiber 3. Ability to bind (adsorption) molecules • Decreased absorption of lipids • Increased bile excretion • Lower serum cholesterol • Altered mineral balance 4. Fermentability by intestinal bacteria • Microflora produces SCFAs - energy - cell proliferation -increases water absorption in the colon CO2, H2, CH4 Soluble Fiber SCFA Fermented • • • Fuel for cells ≈1.5-2.5 kcal/g Acetic acid Butyric acid Proprionic acid Blood stream Pre & Pro – biotic Diets Medical Nutritional Therapy • Pro-biotic - ingestion of certain foods with live cultures containing certain strains of bacteria to increase the counts of specific microflora of the GI tract -Yogurt -survive digestion and then colonize lower GI tract • Prebiotic -food ingredients that are not digested or absorbed but can stimulate the growth/activity of selected types of bacteria in the colon - Oligofructose or inulin (non-digestible oligosaccharides) Health benefits of Dietary Fiber • • • • • • Promotes softer, larger stool and regularity Slows glucose absorption Increases satiety Reduces blood cholesterol Reduces heath disease Reduces hemorrhoids and diverticula Nutrition and GI disorders • Constipation - reduced by fiber, fluid intake, exercise • Diarrhea • Diverticulosis - Pouches along colon - high fiber diet reduces formation Recommended Dietary Fiber Intake • Adequate intake (14g/1000 kcal): - 25 g/day for women - 38 g/day for men - US intake: 13-17 g/day • Too much fiber (>60 g/day) - require extra intake of fluid - binds to some minerals (Fe & Zn) - fill the stomach of young child quickly