Transcript Document
UNIT 3: PROTEINS AND HEALTH Overview of Protein In the U.S., diets are rich in protein; other parts of world may be deficient Proteins provide 4 kcal/g Proteins consist of amino acids linked via peptide bonds Amino Acids 20 different AA to function: 11 are nonessential (can be synthesized in the body from the essential amino acids) 9 are essential (cannot be synthesized in the body, dietary intake is a must) Amino acid structure Central C At least 1 amino group (-NH2) At least 1 carboxyl (acid) group (-COOH) Side chain (R group) Makes AA unique The 9 essential amino acids… Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Tyrosine Threonine Tryptophan Valine What are the functions of protein? What are the functions of protein? Dietary protein provides amino acids which will be used to build proteins in the body: Enzymes (i.e., proteins that speed up reactions) Hormones (e.g., insulin, growth hormone, cortisol) Antibodies Transport proteins (e.g., transferrin, albumin) Structural proteins (e.g., muscle, keratin, collagen) Can also provide us with energy (i.e., ATP) Dietary Protein Animal proteins Examples: meat, poultry, fish, eggs, milk, cheese, and yogurt Supply all essential AA “High-quality” or “complete” proteins Plant proteins Examples: legumes, grains, nuts, seeds, and vegetable May be low in one or more essential AA “Lower-quality” or “incomplete” proteins Consume a variety of plant proteins; “complementary proteins” (e.g., rice & beans) Protein Needs Protein equilibrium: when protein consumed = protein lost (for periods of no growth) Positive Protein Balance: when protein consumed > protein lost (for building new tissues, e.g., periods of growth, recovery from illness/injury, weight training) Negative Protein Balance: when protein consumed < protein lost (for periods of chronic kidney disease) What is the problem with eating too much protein on a chronic basis? Limiting amino acids in plants Consume a variety of plant proteins; “complementary proteins” (e.g., rice & beans) How much protein do we need? Infants, 1.5 g/kg/day Toddlers (1-3 y), 1.1 g/kg/day Children (4-13 y), 0.95 g/kg/day Children (14-18 y), 0.85 g/kg/day Adults (> 18 y), 0.8 g /kg/day Pregnant & lactating women, 1.1 g/kg/day Protein digestion & metabolism Mouth & esophagus - none Stomach HCl denatures Pepsin hydrolyzes the peptide bonds Small intestine Pancreatic enzymes (i.e, trypsin, chymotrypsin, carboxypeptidases, proelastase, collagenase) Brush border peptidases (i.e., aminopeptidases, dipeptdylaminopeptidases, tripeptidases) Absorption of amino acids and peptides (i.e., small protein) takes place in the small intestine. Terms to Know… Amino acids Essential & nonessential amino acids Complete & Incomplete proteins Limiting amino acid Kwashiorkor Marasmus Vegetarian Diets Some death rates (cancers, Type 2 diabetes mellitus, obesity, heart disease) are lower What are the health benefits associated with vegetarian diets? What are some health problems associated with vegetarian diets? Types of Vegetarians Vegans Fruitarians Lacto-vegetarians Ovo-vegetarians Lacto-ovo-vegetarians Protein and Nutrient Profiles 6-ounce porterhouse steak 42 grams protein; 44 grams of fat of which 16 grams are saturated fats (~3/4 of the recommended daily intake for saturated fat) 6-ounce salmon 42 grams of protein; 18 grams of fat, 4 grams saturated fat 1 cup cooked lentils 18 grams of protein; < 1 gram of fat.