1. Mosby items and derived items © 2006 by Mosby, Inc. Slide 1 Chapter 4 Proteins Ahmad Adeeb

2. Mosby items and derived items © 2006 by Mosby, Inc. Slide 2 Chapter 4

3. Mosby items and derived items © 2006 by Mosby, Inc. Slide 3 Key Concepts Food proteins provide the amino acids necessary for building and maintaining body tissue. Protein balance, both within the body and in the diet, is essential to life and health. The quality of a protein food, and its ability to meet the body’s needs, is determined by the composition of amino acids.

4. Mosby items and derived items © 2006 by Mosby, Inc. Slide 4 Amino Acids: Basic Building Material Each protein is made up of hundreds of amino acids Amino acids form unique chain sequences to form specific proteins When protein foods are eaten, proteins are broken down into amino acids Amino acids are reassembled in the body to form a variety of proteins

5. Mosby items and derived items © 2006 by Mosby, Inc. Slide 5 Classes of Amino Acids 1-Indispensable amino acids “لا غنى عنه”  Body cannot synthesize 2-Dispensable amino acids“غير اساسي“  Body can synthesize ***Conditionally indispensable amino acids  Normally synthesized but some health conditions may require dietary intake

6. Mosby items and derived items © 2006 by Mosby, Inc. Slide 6 A Healthy Balance Protein balance  Catabolism: breakdown  Anabolism: resynthesis Nitrogen balance  Positive nitrogen balance: body stores more than it excretes  Negative nitrogen balance: body takes in less than it excretes

7. Mosby items and derived items © 2006 by Mosby, Inc. Slide 7 Functions of Protein Tissue building Energy Water balance Metabolism Body defense system

8. Mosby items and derived items © 2006 by Mosby, Inc. Slide 8 Notes Food proteins provide the amino acids necessary for building and maintaining body tissue. Protein balance, both within the body and in the diet, is essential to life and health. The quality of a protein food, and its ability to meet the body’s needs, is determined by the composition of amino acids.

9. Mosby items and derived items © 2006 by Mosby, Inc. Slide 9 Food Sources of Protein Complete proteins  Meat  Soy Incomplete proteins  Plant-origin foods Grains حبوب Legumes قرون النبات Nuts Seeds بذور Fruits and vegetables

10. Mosby items and derived items © 2006 by Mosby, Inc. Slide 10 Vegetarian Diets Must combine foods to cover all amino acid needs Health benefits & risk

11. Mosby items and derived items © 2006 by Mosby, Inc. Slide 11 Digestion of Proteins Mouth Stomach: enzymatic breakdown of protein by proenzymes (zymogens)  Pepsin  Hydrochloric acid  Rennin ” in child” Small intestine  Pancreatic secretions  Intestinal secretions

12. Mosby items and derived items © 2006 by Mosby, Inc. Slide 12 Body Needs for Protein Tissue growth needs Dietary protein quality  Chemical score (CS)  Biological value (BV) Additional needs due to disease

13. Mosby items and derived items © 2006 by Mosby, Inc. Slide 13 Dietary Deficiency or Excess Protein-energy malnutrition  Kwashiorkor  Marasmus Excess protein  Usually means excess fat intake also  Protein displaces other healthy foods in diet  Kidneys stressed  Potential calcium loss

14. Mosby items and derived items © 2006 by Mosby, Inc. Slide 14 Dietary Guides Recommended Dietary Allowances (RDAs)  Relate to age, sex, weight Dietary Reference Intakes (DRI) from National Academy of Sciences  10% to 35% of total caloric intake from protein (children and adults)

15. Mosby items and derived items © 2006 by Mosby, Inc. Slide 15 Protein Needs Assumes individual consumes 2200 kcal per day; based on recommendation of 10% to 35% of total kcalories from protein 2200 kcal x 0.10 – 0.35 = 220 – 770 kcal per day from protein 220 – 770 kcal  4 kcal/g = 55 – 192.5g of protein per day