Proteins and Amino Acids

Chapter 6-Proteins and Amino Acids FCNS 201-Human Nutrition Joan E Quinn, MEd., RD 08/23/21 LEARNING OBJECTIVES OF THE CHAPTER Describe the structure of proteins and explain why adequate amounts of all essential amino acids are required for protein synthesis  Summarize the processes of protein digestion and absorption in the body  Explain the roles of proteins in the body  08/23/21 Learning objectives, CONT Discuss the importance of protein quality and mutual supplementation  Calculate your individual protein RDA and describe how nitrogen balance studies are used in determining the RDA for protein  Compare the positive health aspects of a vegetarian diet with those of a diet that includes meat and describe ways each diet can include adequate nutrients  PROTEIN PERCEPTION 08/23/21 GENERAL INFORMATION    Protein means TO TAKE FIRST PLACE Carbohydrates and fats = energy Proteins = growth, maintenance, and repair 08/23/21 WHERE ARE PROTEINS FOUND?  In the body-1/2 of all dry material of body is protein  20% body weight – 1/3 muscle – 1/5 bone and cartilage – 1/10 skin – remaining 1/5 other tissues + fluids 08/23/21 WHERE ARE PROTEINS FOUND?, CONT  All enzymes are proteins  many hormones  all viruses  Made by both plants and animals  each species builds proteins characteristic to that specific species 08/23/21 THE STRUCTURE OF PROTEINS Chains of amino acids join together to form proteins  There are 20 different naturally occurring amino acids   Each contain an Amino group-NH2  Each contain a Acid group-COOH  Each contain a side chain which distinguished one AA from another 08/23/21 THE STRUCTURE OF AMINO ACIDS side chain amine group acid group NH2 COOH 08/23/21 PROTEINS ARE CHARACTERIZED BY:     types of amino acids within # of times AA is repeated order of the AA’s spatial structure coil-rope like -strong flexible  rod-insoluble & very strong-bones, tendons, connective tissue  globular-blood proteins  amount of cross linking between AA’s  10 08/23/21 Is A High-Protein Diet Harmful?       41 Intake of animal protein increases risk for heart disease Increase calcium loss Excessive intake of red meat is linked with colon cancer Burden on the kidney Increase fluid needs National Academy of Sciences recommend no more than x RDA for protein 08/23/21 FAD DIETS  LOW PROTEIN DIETS  risk wasting body tissue  must provide essential AA’s and sufficient calories for protein sparing 42 08/23/21 Individual Amino Acid Supplement Supplement may cause imbalances and toxicities  Body is designed to handle whole proteins  Supplement can overwhelm the absorptive mechanism  Excess of one AA can hamper absorption of other AAs  43 08/23/21 RELATED DISORDERS  KWASHIORKOR  inadequate protein in the presence of adequate calories  MARASMUS  adequate protein with inadequate calories  PROTEIN CALORIE MALNUTRITION  inadequate calories protein and Kwashiorkor (Fig 6-7)    Low protein density diet Energy needs are marginally met Signs and symptoms:  45 08/23/21 Apathy, listlessness, failure to grow, poor weight gain, change in hair color, nutrient deficiency, flaky skin, fatty infiltration in the liver, massive edema in the abdomen and legs Marasmus      46 08/23/21 Starving to death Insufficient protein, energy, nutrients “skin and bones” appearance Little or no subcutaneous fat Reduce brain growth Vegetarianism 47 08/23/21 Soy Soy protein is similar to animal protein (used in school lunches)  High in linoleic acid and some linolenic acid  Calcium source and bone health  Isoflavones  Heart disease  Cancer  48 08/23/21 VEGETARIANS-HOW DO THEY DO IT? LACTOVEGETARIANS  LACTO-OVO-VEGETARIANS  SEMIVEGETARIANS  VEGANS  49 08/23/21 VEGETARIANISM-THE PROS  Seems to support health well  lower blood pressure  lower heart disease  lower mortality rate from cancer 50 08/23/21 VEGETARIANISM-THE CONS   May have trouble achieving adequate energy-especially in kids Most at risk for deficiencyprotein  iron  b-12  vitamin D  calcium  Zinc  51 08/23/21 52 08/23/21 SELF CHECK-WHAT HAVE YOU LEARNED TONIGHT?  Under certain circumstances, protein can be converted to glucose and so serve the energy needs of the brain True of False?  Too little protein in the diet can have severe consequences, but excess protein has no adverse effects True of False? 53 08/23/21 SELF CHECK-WHAT HAVE YOU LEARNED TONIGHT? Although protein-energy malnutrition (PEM) is prevalent in developing nations, it is not seen in the United States True or False?  Partially completed proteins are not held for completion at a later time when the diet may improve True of False?  An example of a person in negative nitrogen balance is an astronaut True or False?  54 08/23/21 THE END 55 08/23/21