Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein Chapter 5

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Introduction Proteins are “of prime importance” –Versatile roles: needed for muscle contraction, blood clotting, vision, fighting infections, building new tissue, etc.

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 The Chemist’s View of Proteins Atoms comprising protein –Carbon, hydrogen, oxygen, and nitrogen Amino: contains nitrogen About 20 different amino acids in proteins Amino acids bond together –Dipeptide –Tripeptide –Polypeptide

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 The Chemist’s View of Proteins (cont’d.) What determines the shape of polypeptide chains? –Different shapes: enable proteins to perform different tasks in the body

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 The Chemist’s View of Proteins (cont’d.) Nonessential amino acids –The body can make them for itself Essential amino acids –Must be obtained in foods What is a conditionally essential amino acid?

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein Digestion and Absorption Long peptide chains + enzymes Short peptides + enzymes Tripeptides and dipeptides + enzymes Amino acids

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein Turnover and Nitrogen Balance Protein turnover –Continual process in which proteins are made and broken down –What are some specific examples? –Amino acids needed each day: support new growth and maintenance of cells Nitrogen balance (nitrogen equilibrium) –Nitrogen intake equals nitrogen output

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Roles of Body Proteins Structural components –Muscle, bones, teeth, tendons, cartilage, blood vessels, etc. Enzymes –Catalysts essential to all life processes Some enzymes: break food proteins into amino acids Other enzymes: build long chains of amino acids

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Roles of Body Proteins (cont’d.) Transporters –Move substances around the body Protein hemoglobin: carries oxygen Lipoproteins: transport lipids Regulators of fluid and electrolyte balance –Maintain necessary amounts and types of fluid and minerals in each compartment of the body fluids

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Roles of Body Proteins (cont’d.) Regulators of acid-base balance –Maintain the balance between acids and bases within the body’s fluids –What are the conditions of acidosis and alkalosis? Antibodies –Produced when body detects antigens –What is immunity?

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Roles of Body Proteins (cont’d.) Hormones –Some hormones: comprised of proteins Source of energy and glucose –When glucose or fatty acids are limited Functions of proteins (Table 5-2)

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein and Health Protein deficiency –Slow growth in children, impaired brain and kidney function, weakened immune defenses, and impaired nutrient absorption –Conditions Protein-energy malnutrition (PEM) Severe acute malnutrition (SAM): kwashiorkor and marasmus Chronic malnutrition

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein and Health (cont’d.) Protein deficiency –What are ways to prevent and treat malnutrition? Protein excess –Heart disease –Kidney disease Protein and amino acid supplements –Unsupported by scientific studies

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein and Health (cont’d.) Protein recommendations and intakes –RDA Adult: 0.8 gram per kilogram (2.2 pounds) of healthy body weight –DRI Men: 10 to 35 percent of kcalories Women, children, and elderly: 13 to 15 percent kcalories

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein in Foods High-quality proteins –Provide adequate amounts of all of the essential amino acids –Influenced by: Protein digestibility Amino acid composition –Limiting amino acid: essential amino acid Available in the shortest supply relative to the amount needed to support protein synthesis

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein in Foods (cont’d.) High-quality proteins –Generally derived from animal foods –Soy protein Complementary proteins –Two protein-rich foods combined to obtain all the essential amino acids in amounts sufficient to support health

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014

Nutrition for Health and Health Care, 5th Edition DeBruyne ■ Pinna © Cengage Learning 2014 Protein in Foods (cont’d.) Protein sparing –Carbohydrate and fat: allow amino acids to be used to build body proteins Absence of carbohydrate and fat –Body will use protein to meet energy needs Protein on food labels –% Daily Value: reflects quantity and quality