Chapter 6 Protein and Amino Acids

Copyright 2010, John Wiley & Sons, Inc. Sources of Protein in the Diet Protein deficiency is rare in the United States. In the US, about two-thirds of dietary protein comes from meat, poultry, seafood, eggs and dairy products. Most of the world relies on plant proteins from grains and vegetables. As a country’s economy improves, the proportion of animal foods in the diet tends to increase.

Copyright 2010, John Wiley & Sons, Inc. Sources of Protein in the Diet

Copyright 2010, John Wiley & Sons, Inc. Sources of Protein in the Diet

Copyright 2010, John Wiley & Sons, Inc. Animal versus Plant Protein Animal products provide sources of protein, B vitamins and minerals such as iron, zinc and calcium. However, animal products are low in fiber and can be high in fat. Plant sources of protein are also a good source of B vitamins, iron, zinc, fiber and calcium, but in less absorbable forms.

Copyright 2010, John Wiley & Sons, Inc. Amino Acids Amino acids are the building blocks of protein. Each amino acid contains a central carbon atom bound to a hydrogen atom, an amino group, an acid group and a side chain. Essential amino acids cannot be synthesized by the human body in sufficient amounts to meet needs. Essential amino acids must be included in the diet.

Copyright 2010, John Wiley & Sons, Inc. Amino Acids and Protein Structure

Copyright 2010, John Wiley & Sons, Inc. Amino Acids and Protein Structure

Copyright 2010, John Wiley & Sons, Inc. Phenylketonuria Aspartame in sweetener(soda) breakdown in digestive tract and releases Phenylalanine Individuals with disease of Phenylketonuria can not properly metabolize Phenylalanine, therefore Phenylketones build up in the blood and interfere With brain development

Copyright 2010, John Wiley & Sons, Inc. Protein Digestion and Absorption Various transport proteins help in absorption

Copyright 2010, John Wiley & Sons, Inc. Synthesizing Protein

Copyright 2010, John Wiley & Sons, Inc. Synthesizing Protein Transamination: Synthesis of nonessential amino acid by transferring the amino group from one amino acid to a carbon containing molecule

Copyright 2010, John Wiley & Sons, Inc. Synthesizing Protein

Copyright 2010, John Wiley & Sons, Inc. Synthesizing Protein

Copyright 2010, John Wiley & Sons, Inc. Function of Protein in the Body Collagen is the most abundant protein In the body with structural role Enzymes that help in breakdown of starch are protein molecules Transport protein: Hemoglobin give the red color to blood cell, also hemoglobin shuttles oxygen to body cells and carries away CO2

Copyright 2010, John Wiley & Sons, Inc. Function of Protein in the Body Immunization against measles using dead or inactive vaccine produce protein called antibody by immune system which specifically attack measles virus Protein actin and myosin help in contraction of muscles (arms, legs, heart) When protein level falls in blood, the fluid leaks out and accumulates in the tissues causing “edema” (swelling). Protein regulate fluid balance

Copyright 2010, John Wiley & Sons, Inc. Protein as a Source of Energy Deamination produce: 3 carbon molecule to synthesize glucose Acetyl-CoA enter to aerobic Cycle Other molecules enter directly to aerobic cycle

Copyright 2010, John Wiley & Sons, Inc. Protein Deficiency Protein-energy malnutrition (PEM) is a term that covers a range of protein deficiency conditions that may include only protein deficiency or protein deficiency plus energy deficiency. Kwashiorkor is a pure protein deficiency. Marasmus is an energy deficiency.

Copyright 2010, John Wiley & Sons, Inc. Protein Allergies Food allergies are triggered when a protein from the diet is absorbed without being completely digested. Protein from milk, eggs, nuts, wheat, soy, fish and shellfish and peanuts are common sources of food allergies. A rapid, severe allergic reaction is called anaphylaxis – multi-symptom allergic condition People with GI disease are prone to allergies because their damaged intestine allows for the absorption of whole proteins.

Copyright 2010, John Wiley & Sons, Inc. Food Allergy Labeling

Copyright 2010, John Wiley & Sons, Inc. Protein Excess Elevated protein intakes over long periods of time can results in: Hydration and kidney function issues Bone health issues Increased risk of heart disease and cancer

Copyright 2010, John Wiley & Sons, Inc. Meeting Protein Needs: Nitrogen Balance Maintaining a constant body weight by exercising More protein degradation than being synthesizes More protein synthesis than degradation i.e. gaining weight as in pregnancy and weight lifting

Copyright 2010, John Wiley & Sons, Inc. General Protein Requirements RDA for protein for adults (70kg/154lbs) = 54g protein/day

Copyright 2010, John Wiley & Sons, Inc. Varying Protein Needs of Athletes To maintain blood glucose during endurance events: 1.2 – 1.4 g of protein/kg of body weight For muscle growth need: 1.2 – 1.7 g of protein/kg of body weight

Copyright 2010, John Wiley & Sons, Inc. Protein and Amino Acid Supplements

Copyright 2010, John Wiley & Sons, Inc. Choosing Protein Wisely Meat, beans and milk groups provide more concentrated sources of proteins. Dry beans and peas are the most concentrated sources of plant proteins.

Copyright 2010, John Wiley & Sons, Inc. Types of Vegetarian Diets

Copyright 2010, John Wiley & Sons, Inc. Nutrient Needs with a Vegan Diet

Copyright 2010, John Wiley & Sons, Inc. Soy Protein

Copyright 2010, John Wiley & Sons, Inc. What Should I Eat? Protein Sources Get protein without too much saturated fat Plan on poultry or fish. Choose lean cuts of red meat. Grill, roast, or broil so that the fat will end up in the pan or the fire. Choose low-fat or reduced-fat milk. Eat both animal and plant proteins Have your beef or chicken in a stir-fry with lots of vegetables. Serve a small portion of meat over noodles. Add nuts and seeds to snacks and salads. Have a meatless meal at least once a week. Go with beans Try hummus—made from ground chickpeas and sesame seeds. Add kidney beans or chickpeas to soups. Snack on soy beans. Enjoy tacos or burritos stuffed with pinto beans or black beans.

Copyright 2010, John Wiley & Sons, Inc. End of Chapter 6 Copyright 2010 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein..