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  1. 1. Protein Charles Lohman
  2. 2. Amino Acids <ul><li>Amino Acids </li></ul><ul><ul><li>Side groups of amino acids vary from one amino acid to the next </li></ul></ul><ul><ul><li>These differing side groups are what make proteins more complex than either carbohydrates or lipids (fats) </li></ul></ul><ul><ul><li>Proteins are made up of 20 different amino acids , each with a different side group </li></ul></ul><ul><li>Nonessential amino Acids </li></ul><ul><ul><li>Amino acids the body can synthesize </li></ul></ul><ul><ul><li>Consist of more than half of the 20 </li></ul></ul>
  3. 3. Amino Acids <ul><li>Essential Amino Acids </li></ul><ul><ul><li>Amino acids the body CANNOT synthesize </li></ul></ul><ul><ul><li>There are 9 of them </li></ul></ul><ul><li>Conditionally Essential Amino Acids </li></ul><ul><ul><li>When a nonessential amino acid becomes essential under special circumstances </li></ul></ul><ul><ul><li>Such as with the disease phenylkentonuria when the body is unable to make the conversion of phenylalanine to tyrosine. So tyrosine becomes a conditionally essential amino acid </li></ul></ul>
  4. 4. Roles of Protein <ul><li>Growth and Maintenance </li></ul><ul><ul><li>Proteins form the building blocks of muscles, blood, and skin from the time of conception </li></ul></ul><ul><ul><li>Collagen is a protein that provides the material for bones, teeth, ligaments, and tendons. </li></ul></ul><ul><ul><li>Collagen is also the strengthening glue between the cells of the artery walls that enables the arteries to withstand the pressure of the blood surging through them with each heartbeat </li></ul></ul><ul><ul><li>Proteins are also needed for replacing dead or damaged cells </li></ul></ul>
  5. 5. Roles of Protein <ul><li>Enzymes </li></ul><ul><ul><li>Some proteins act as enzymes </li></ul></ul><ul><ul><li>Enzymes not only break down substances, but they also build substances such as bone, and transform one substance into another </li></ul></ul><ul><ul><li>Enzymes themselves are not altered by the reactions they facilitate, but act as catalysts, permitting reactions to occur more quickly and efficiently </li></ul></ul>
  6. 6. Roles of Proteins <ul><li>Hormones </li></ul><ul><ul><li>Some hormones are proteins , regulating a variety of actions in the body </li></ul></ul><ul><ul><li>For example insulin stimulates the transport proteins of the muscles and the adipose tissue to pump glucose into the cells faster than it can leak out </li></ul></ul><ul><li>Fluid balance </li></ul><ul><ul><li>Disruption of fluid balance can cause edema </li></ul></ul><ul><ul><li>Edema is when there are excessive amounts of interstitial fluid (spaces between the cells) </li></ul></ul><ul><ul><li>Edema can be caused by </li></ul></ul><ul><ul><ul><li>excessive protein loss caused by kidney disease or large wounds, </li></ul></ul></ul><ul><ul><ul><li>inadequate protein synthesis caused by liver disease </li></ul></ul></ul><ul><ul><ul><li>inadequate dietary intake of protein </li></ul></ul></ul>
  7. 7. Roles of Proteins <ul><li>As Acid base Regulators </li></ul><ul><ul><li>Proteins help to maintain the balance between acids and bases within the body fluids </li></ul></ul><ul><ul><li>The body’s acid base balance is tightly controlled </li></ul></ul><ul><ul><li>The extremes of acidosis and alkalosis leads to coma and death because they denature (disturbing the shape of the protein) working proteins </li></ul></ul><ul><li>As Transporters </li></ul><ul><ul><li>Some proteins move about the body fluids, carrying nutrients and other molecules </li></ul></ul><ul><ul><li>The protein hemoglobin carries oxygen from the lungs to the cells </li></ul></ul><ul><ul><li>Lipoproteins transport lipids </li></ul></ul><ul><ul><li>Some transport proteins carry vitamins and minerals </li></ul></ul>
  8. 8. Roles of Proteins <ul><li>As Antibodies </li></ul><ul><ul><li>Antibodies are large proteins of the blood and body fluids, produced by the immune system in response to the invasion of a body by foreign molecules </li></ul></ul><ul><li>As a Source of Energy and Glucose </li></ul><ul><ul><li>During times of starvation or insufficient carbohydrate intake, protein will be sacrificed tom provide energy and glucose </li></ul></ul><ul><ul><li>The body will break down its tissue proteins to make amino acids available for energy and glucose production </li></ul></ul><ul><ul><li>Protein can therefore maintain blood glucose levels, but at the expense of losing lean body tissue </li></ul></ul>
  9. 9. Protein Quality <ul><li>Digestibility </li></ul><ul><ul><li>Proteins must be digested before they can provide amino acids </li></ul></ul><ul><ul><li>This depends on such factors as the proteins source and other foods eaten with it </li></ul></ul><ul><ul><li>Digestibility of animal proteins is about 90 to 99 percent </li></ul></ul><ul><ul><li>Digestibility of plant proteins is about 70 to 90 percent </li></ul></ul><ul><ul><li>Digestibility of soy and legumes is over 90 percent digestibility </li></ul></ul><ul><li>High Quality proteins </li></ul><ul><ul><li>Foods derived from animals (meat, fish, poultry, cheese, eggs, yogurt, and milk) provide high quality protein </li></ul></ul><ul><ul><li>Soy is also considered a high quality protein </li></ul></ul><ul><ul><li>Plant proteins (vegetables, nuts, seeds, grains, and legumes) tend to be limiting in one or more essential amino acids </li></ul></ul><ul><ul><li>A limiting amino acid is an amino acid in less than the amount needed to support protein synthesis </li></ul></ul>
  10. 10. Protein Quality <ul><li>Complementary Proteins </li></ul><ul><ul><li>Two or more dietary proteins whose amino acid assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other </li></ul></ul><ul><ul><li>When used by vegetarians it can help them receive all the amino acids needed over the course of a day by eating a variety of whole grains, legumes, seeds, nuts, and vegetables </li></ul></ul>
  11. 11. Health Effects and Recommended Intakes of Protein <ul><li>Protein Energy Malnutrition (PEM) </li></ul><ul><ul><li>A deficiency of protein, energy, or both </li></ul></ul><ul><ul><li>PEM can be classified in two forms, marasmus, and kwashiorkor which differ in their clinical features </li></ul></ul><ul><li>Marasmus </li></ul><ul><ul><li>means “dying away” and reflects a severe deprivation of food over a long period of time </li></ul></ul><ul><ul><li>Occurs commonly in children from 6 to 18 months in all overpopulated and impoverished areas of the world </li></ul></ul><ul><ul><li>Physically characterized as skin and bones </li></ul></ul>
  12. 12. Health Effects and Recommended Intakes of Protein <ul><li>Kwashiorkor </li></ul><ul><ul><li>Sudden and recent deprivation of food </li></ul></ul><ul><ul><li>Usually develops rapidly as a result of protein deficiency or, more commonly, is precipitated by an illness such as measles or another infection </li></ul></ul><ul><ul><li>Some muscle wasting may occur </li></ul></ul><ul><ul><li>Proteins and hormones that previously maintained fluid balance diminish, and fluid leaks into the interstitial spaces </li></ul></ul><ul><ul><li>Child’s limbs and abdomen become swollen with edema which is a distinguishing feature of the disease </li></ul></ul>
  13. 13. Health Effects of Protein <ul><li>Heart Disease </li></ul><ul><ul><li>A high protein diet may contribute to the progression of heart disease </li></ul></ul><ul><ul><li>There is a correlation between animal protein intake and heart disease </li></ul></ul><ul><ul><li>Substituting vegetable protein for animal protein improves blood lipids and decreases heart disease mortality </li></ul></ul><ul><li>Cancer </li></ul><ul><ul><li>Population studies suggest a correlation between high intakes of animal proteins and some types of cancers notably, cancer of the colon, breast, kidneys, pancreas, and prostate </li></ul></ul><ul><li>Adult Bone Loss </li></ul><ul><ul><li>When protein intake is high, calcium excretion increases. Whether excess protein depletes the bones of their chief mineral depends upon the ratio of calcium intake to protein intake </li></ul></ul><ul><ul><li>Some research suggests that animal protein may be more detrimental to calcium metabolism and bone health than vegetable protein </li></ul></ul><ul><ul><li>However excess protein whether from animal or vegetable sources increase calcium excretion </li></ul></ul>
  14. 14. Health Effects of Protein <ul><li>Weight Control </li></ul><ul><ul><li>Dietary protein may play a role in increasing body weight </li></ul></ul><ul><ul><li>Protein rich foods are often fat rich foods that contribute to weight gain with accompanying health risks </li></ul></ul><ul><ul><li>Weight loss gimmicks that encourage a high protein, low carbohydrate diet may be temporarily effective </li></ul></ul><ul><ul><li>Diets that provide adequate protein, moderate fat, and sufficient energy from carbohydrates can better support weight loss by providing satiety </li></ul></ul><ul><li>Kidney Disease </li></ul><ul><ul><li>High protein intake increases the work of the kidneys, BUT does not appear to diminish kidney function or cause kidney disease </li></ul></ul><ul><ul><li>Restricting dietary protein, however, may help to slow the progression of kidney disease and limit the formation of kidney stones in people who have these conditions </li></ul></ul>
  15. 15. Recommended Intakes of Protein <ul><li>Protein RDA </li></ul><ul><ul><li>Food protein is the only source of the essential amino acids and second it is the only practical source of nitrogen </li></ul></ul><ul><ul><li>Protein RDA for adults is 0.8 (10% to 35% of energy intake) grams per kilogram of healthy body weight per day </li></ul></ul><ul><ul><li>For infants and children, the RDA is slightly higher </li></ul></ul><ul><ul><li>For teens 14 to 18, RDA is 0.85g/kg/day </li></ul></ul>
  16. 16. Protein Supplements <ul><li>Protein Powders </li></ul><ul><ul><li>Body builds muscle from amino acids so many athletes take protein powders with the false hope of stimulating muscle growth </li></ul></ul><ul><ul><li>Muscle work builds muscle; protein supplements do not, and athletes do not need them </li></ul></ul><ul><ul><li>They do not improve athletic performance </li></ul></ul><ul><ul><li>Protein powders can supply amino acids to the body, but nature’s protein sources – lean meat, milk, eggs, and legumes – supply all these amino acids and more </li></ul></ul><ul><ul><li>Remember excess protein will just get stored as FAT </li></ul></ul>