Nutrition - Chapter 6 Notes


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Nutrition - Chapter 6 Notes

  1. 1. Chapter 6 Lecture Outline Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display
  2. 2. Overview of Protein <ul><li>Body is made up of thousands of proteins </li></ul><ul><li>Contains nitrogen, carbon, hydrogen, and oxygen </li></ul><ul><li>Functions </li></ul><ul><ul><li>Regulates and maintains body functions </li></ul></ul><ul><ul><li>Provides essential form of nitrogen (in the form of amino acids) </li></ul></ul>
  3. 3. Amino Acid <ul><li>R group Acid group </li></ul><ul><li>Nitrogen group </li></ul>NH2 O R C C OH H
  4. 4. Relationship of Essential and Non-essential Amino Acids <ul><li>Example: </li></ul><ul><li>Phenylalanine    tyrosine </li></ul><ul><li>(essential non-essential) </li></ul><ul><li>But in PKU diagnosed individuals: </li></ul><ul><li>Phenylalanine    tyrosine </li></ul><ul><li>(essential NOW essential) </li></ul>
  5. 5. Classification of Amino Acids
  6. 6. Protein Synthesis <ul><li>DNA contains coded instructions </li></ul><ul><li>Copies of codes </li></ul><ul><ul><li>Transferred to the cytoplasm (via mRNA) </li></ul></ul><ul><li>Amino acids added one at a time </li></ul><ul><ul><li>With aid of transfer RNA (tRNA) </li></ul></ul><ul><li>Requires energy </li></ul>
  7. 7. Protein Synthesis
  8. 8. Protein Organization <ul><li>Order of amino acids in a protein determines its ultimate shape </li></ul><ul><li>Protein’s final shape determines its function in the body </li></ul>
  9. 9. Sickle Cell Anemia
  10. 10. Denaturation of Proteins <ul><li>Heat/acid/alkaline/enzymes </li></ul><ul><li>Results in alteration of the protein’s </li></ul><ul><li>three-dimensional structure </li></ul>
  11. 11. Protein in Foods
  12. 12. Animal Protein <ul><li>Contribution to our diet </li></ul><ul><ul><li>~70% of our protein intake </li></ul></ul><ul><li>Top 5 contributors of protein in U.S. diet: </li></ul><ul><ul><li>Beef </li></ul></ul><ul><ul><li>Poultry </li></ul></ul><ul><ul><li>Milk </li></ul></ul><ul><ul><li>White bread </li></ul></ul><ul><ul><li>Cheese </li></ul></ul><ul><li>Worldwide, 35% comes from animal sources </li></ul>
  13. 13. Dietary Protein <ul><li>High-quality </li></ul><ul><ul><li>Complete </li></ul></ul><ul><li>Low-quality </li></ul><ul><ul><li>Incomplete </li></ul></ul><ul><li>All-or-none principle in protein synthesis </li></ul><ul><li>Limiting amino acids </li></ul><ul><li>Complementary proteins </li></ul>
  14. 14. Health and Plant Proteins <ul><li>Heart healthy </li></ul><ul><li>Cancer-fighting </li></ul><ul><li>Bone health </li></ul><ul><li>Better glucose control </li></ul><ul><li>Soy and menopausal symptoms </li></ul>
  15. 15. Plant Sources <ul><li>Provide protein, minerals, and dietary fiber </li></ul><ul><li>Contain no cholesterol </li></ul><ul><li>Limited saturated fats </li></ul><ul><li>High fiber </li></ul><ul><ul><li>Time needed to adjust to the higher fiber load </li></ul></ul>
  16. 16. Complementary Protein <ul><ul><li>Food 1 Food 2 Combined </li></ul></ul><ul><ul><li> </li></ul></ul><ul><li>CC CCCC </li></ul><ul><li>AAAA AA CAR CAR CAR </li></ul><ul><li>RRR RRR CAR CAR CAR </li></ul>
  17. 17. Digestion of Protein in the Stomach <ul><li>Denatured </li></ul><ul><ul><li>By cooking and acid in the stomach </li></ul></ul><ul><li>Gastrin </li></ul><ul><ul><li>Stimulates the release of acid and pepsin </li></ul></ul><ul><li>Pepsin </li></ul><ul><ul><li>Breaks down proteins </li></ul></ul>
  18. 19. Digestion of Protein in the Small Intestine <ul><li>Release of CCK </li></ul><ul><li>Pancreatic enzymes: </li></ul><ul><ul><li>Trypsin, among others, into the duodenum </li></ul></ul><ul><li>Peptones  peptides  amino acids </li></ul><ul><li>Small peptides and amino acids </li></ul><ul><ul><li>Ready for absorption </li></ul></ul>
  19. 20. Protein Turnover <ul><li>Breakdown and synthesis </li></ul><ul><li>Responds to change </li></ul><ul><li>Amino acids can be recycled </li></ul>
  20. 21. Fluid Balance
  21. 22. Protein Absorption <ul><li>Site of digestion </li></ul><ul><ul><li>Microvilli surface and within absorptive cells </li></ul></ul><ul><li>Many different amino acid transport mechanisms </li></ul><ul><li>Active absorption </li></ul><ul><li>Amino acids are sent to the liver </li></ul><ul><ul><li>Via portal vein </li></ul></ul>
  22. 23. Metabolism of Amino Acids
  23. 24. Functions of Proteins <ul><li>Building blocks of body components </li></ul><ul><li>Fluid balance maintenance </li></ul><ul><li>Acid/base balance (contribute to) </li></ul><ul><li>Building blocks of hormones and enzymes </li></ul><ul><li>Immune function </li></ul><ul><li>Gluconeogenesis </li></ul><ul><li>Energy yielding (non-preferred source) </li></ul>
  24. 25. RDA for Protein <ul><li>Promotes equilibrium </li></ul><ul><li>0.8 gm of protein / kg of healthy body weight </li></ul><ul><li>154 lb. = 70 kg </li></ul><ul><li>2.2 kg/lb. </li></ul><ul><li>70 kg x 0.8 g protein = 56 g protein </li></ul><ul><li>kg healthy body weight </li></ul>
  25. 26. Protein Balance
  26. 27. RDA for Protein <ul><li>Increased by ~10-15 gm /day for pregnancy </li></ul><ul><li>Endurance athletes </li></ul><ul><ul><li>May need 1.2 – 1.7 gm/kg healthy weight </li></ul></ul><ul><li>Provide about 8-10% of total kcal </li></ul><ul><li>Most of us eat more than the RDA for protein </li></ul><ul><li>Excess protein cannot be stored as protein </li></ul>
  27. 28. Is a High-Protein Diet Harmful? <ul><li>Low in plant foods (fiber), vitamins, phytochemicals </li></ul><ul><li>High in saturated fat and cholesterol </li></ul><ul><li>Excessive intake of processed red meat is linked with colon cancer </li></ul><ul><li>Burden on the kidney </li></ul><ul><li>May increase calcium loss in the urine </li></ul>
  28. 29. Malnutrition <ul><li>Protein-Energy Malnutrition </li></ul><ul><li>Marasmus </li></ul><ul><ul><li>Seen in hospitalized patients </li></ul></ul><ul><li>Kwashiorkor </li></ul>
  29. 30. Protein Calorie Malnutrition
  30. 31. Vegetarian Diets <ul><li>Why become a vegetarian? </li></ul><ul><li>Vegans </li></ul><ul><li>Fruitarians </li></ul><ul><li>Lactovegetarians </li></ul><ul><li>Lactoovovegetarians </li></ul><ul><li>Concerns for infants and children </li></ul>