02 24 14 Proteins and Amino Acids What Do Proteins Do Build new tissue Functional unit few to thousands amino acids o Enzymes o Hormones o Antibodies Physiology metabolism o Fluid and electrolyte balance o Acid base balance o Energy o Transportation ie Lipoproteins o Blood clotting How Much Protein Do We Need DRI recommendation depends on size and stage of growth 8g kg of body weight minimum is 10 of total calories athletes need slightly more 1 0 g kg Classification of Amino Acids Essential AA s Other AA s Protein Structure Amine group links with the acidic end of the next amino acid AA w electronically charged side chains are attracted to H2O SS w neutral side chains are repelled by water seek each other Have very convoluted shapes Single amino acids w different side chains valine leucine tyrosine can bond to form a strand of amino acids part of a protein Protein structure and function are disrupted by a variety of things o Heat acid alcohol base salts Hemoglobin quaternary Protein Denaturation Protein Digestion and Absorption Amino Acid Metabolism Carried to the liver o Used by liver or released into blood to be taken up by other cells Cells can then use amino acids o Make their proteins for their own use o Make proteins that are released into the lymph or blood for other uses When necessary body cells can use amino acids for energy Protein Deficiencies Marasmus chronic inadequate food intake Protein Quality o Inadequate energy vitamin mineral and protein intake o Person is shriveled and lean all over Kwashiorkor o Swollen belly and skin rash are present o Severe acute malnutrition Too little protein to support body functions Malnutrition in US o PEM is not unknown millions live on edge of hunger Inner cities Indian reservations rural areas some elderly people hungry homeless children people suffering from anorexia nervosa people with wasting illnesses AIDS cancer drug alcohol addictions If diet doesn t contain essential amino acids in adequate quantities protein synthesis in body can be slowed Complete protein a food that contains all 9 essential amino acids Most plant foods don t contain all 9 o Legumes notably soybeans are exception May have implications for vegetarians Complimentary Proteins o 2 proteins whose amino acid assortments compliment each other in such a way that the essentioal amino acids missing from one are supplied by the other probably not an issue in countries where overall dietary intake is adequate o if it is an issue only for vegans more of an issure in countries where dietary sources of protein are limited Vegetarian Diets Benefits diseases pressure they omit rheumatoid arthritis Healthier Strong evidence links vegetarian diets w reduced incidences of chronic Less obesity defense against certain cancers less heart disease high blood May help prevent diabetes osteoporosis diverticular disease gallstones and Some effects may arise from what vegetarians inclue in the diet than what Balanced adequate diet in which lean meats and seafood eggs ad milk are included w fruits veggies and whole grains can be very healthy Both meat eaters and lacto ovo vegetarians can rely on their diets during critical times of life Vegan diet can pose challenges o Meat provides abundant iron zinc vitamin B12 needed by everyone but in particular by pregnant women children and teens Both vegetarian and meat containing diets can lack nutrients if not properly balanced Poorly planned meat eater s diets may lack vitamin A C folate and fiber Poorly planned vegetarian diets lack iron zinc calcium omega 3 fatty acids vitamin D B12 More Environmentally Friendly Meat industry responsible for more greenhouse gas emissions than Raising livestock also leads to land and water degradation due to overgrazing transportation industry waste products in environment fruits veggies Growing corn for feed contributes to monoculture less land to grow Meat raised locally organically will have lower impact on environment Cows fed grass have lower impact on environment and nutritional content of meat is more favorable for humans Protein Excess Diets high in protein rich foods o Often associated w obesity and accompanying risks o Animal protein sources in particular can be high in saturated fat Known contributor to atherosclerosis and heart disease Effect of animal protein itself on heart is uncertain but substituting plant protein for animal improves indicators of heart disease risk Animals fed experimentally high protein diets o Often develop enlarged kidneys or livers In humans high protein diet worsens existing kidney problems and may accelerate a decline in only mildly impaired kidneys o One of most effective treatments for people w established kidney problems is to reduce protein intakes to slow progression of disease o Protein of high biological value Protein intake and calcium o Mixed evidence about whether high intake of protein from animal sources accompanied by very low calcium and low fruit veggie intake can accelerate adult bone loss o Feeding purified protein to human subjects causes calium to be spilled from urine o Diets high particularly animal protein correlate w higher incidence of hip fractures in some populations Reverse may be true in malnourished elderly individuals in whome protein deficiency and hip fracture often occur together o Restoring dietary protein and giving certain calcium and vitamin D supplements can improve bone status High Protein Diets o Forces body to use proteins for energy o Tissue proteins and dietary proteins o Limit overall food intake less calorie intake o Not healthy long term diet o Potential short term side effects o Much research still ongoing o Not proven to be more effective than high CHO diets in long term o Most effective diet is one that people stick w for long term 02 26 14 Vitamins Vitamins essential organic not energy yielding needed in small amounts micronutrients Nomenclature and classification Nomenclature by discovered order Classification o Fat soluble vitamins Vitamins A D E K Requires bile for absorption Need blood carrier for transport Greater body storage and high likelihood of toxicity than water soluble vitamins o Water soluble vitamins Thiamin B1 Riboflavin B2 Niacin B3 Pantothenic acid Vitamin B6 Folate Vitamin B12 Biotin Ascorbic acid C Lower body storage and high likelihood of toxicity than fat soluble vitamins Usually excreted in urine Nobel prizes for vitamin discovery 1929 Thiamin Jansen and Donath 1937 Vitamin C Albert Szent
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