Lipids ch5

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Lipids ch5

  1. 1. Lipids The body’s preferred energy storage form
  2. 2. Forms of Lipids <ul><li>Fatty acids = basic unit of lipid </li></ul><ul><li>Triglycerides = 3 fatty acids attached to a glycerol backbone </li></ul><ul><li>Phospholipids = 2 fatty acids and a phosphate head attached to a glycerol backbone </li></ul><ul><li>Sterols = multi-ring structures, soluble in lipids </li></ul>
  3. 3. Fig. 5.4
  4. 5. Digestion/Absorption of Lipids <ul><li>Bile – emulsification </li></ul><ul><ul><li>98% reabsorbed unless use Rx, plant sterols/stannols, soluble fiber </li></ul></ul><ul><li>Lipase – separates triglycerides into individual fatty acids </li></ul>Fig. 5.11
  5. 6. Thinking Time <ul><li>Which organ makes bile? Which organ stores bile? Where is it secreted? </li></ul><ul><li>Which organ makes the lipase enzyme that is used to digest lipids in the small intestine? </li></ul>
  6. 7. Digestion/Absorption of Lipids <ul><li>Fatty acids absorbed by small intestine cells, packaged into chylomicrons , released into the lymphatic system </li></ul>Fig. 5.12
  7. 8. Fat as Fuel <ul><li>9 kcal/gram </li></ul><ul><li>Preferred storage form in the body (adipose tissue) </li></ul><ul><ul><li>Can increase 50 times in weight </li></ul></ul><ul><li>½ of energy used at rest or with light activity is from fat </li></ul><ul><li>Need adequate CHO intake to completely metabolize fat </li></ul>
  8. 9. Fat for Insulation/Protection <ul><li>Insulating layer beneath skin </li></ul><ul><li>Protecting layer around organs </li></ul><ul><li>Females with anorexia nervosa who lose more than 25% of body weight and become virtually fat-free  become amenorrheic, bone loss, grow lanugo, at risk for internal organ damage </li></ul>
  9. 10. Fat for Transporting/Storing Vitamins <ul><li>Fat-soluble vitamins (A, D, E, K) are absorbed into the lymphatic system with lipid </li></ul><ul><li>Fat-soluble vitamins are stored in adipose tissue </li></ul><ul><li>Diseases affecting lipid absorption also hinder fat-soluble vitamin absorption </li></ul>
  10. 11. Fat Intake Recommendations <ul><li>30% or less of total kcal intake </li></ul><ul><ul><li>1/3 (or 10%) from each of the three classes of fatty acids </li></ul></ul><ul><li>Less fat if trying to lose or maintain body weight </li></ul><ul><li>More if trying to gain weight </li></ul>
  11. 12. Classes of Fatty Acids <ul><li>Based on number of carbon-carbon double bonds in the hydrocarbon chain </li></ul><ul><li>Related to health benefits or risk </li></ul><ul><li>Only 2 are essential </li></ul>
  12. 13. Classes of Fatty Acids <ul><li>Three classes: </li></ul><ul><ul><li>Saturated fatty acids </li></ul></ul><ul><ul><ul><li>No double bonds, chain is completely “saturated” with hydrogen instead </li></ul></ul></ul><ul><ul><li>Monounsaturated fatty acids (MUFA) </li></ul></ul><ul><ul><ul><li>One double bond </li></ul></ul></ul><ul><ul><li>Polyunsaturated fatty acids (PUFA) </li></ul></ul><ul><ul><ul><li>Two or more double bonds </li></ul></ul></ul>
  13. 14. Fig. 5.1
  14. 15. Saturated Fatty Acids <ul><li>Food source: primarily animal </li></ul><ul><ul><li>Also found in coconut, palm oils </li></ul></ul><ul><li>Health consequence: </li></ul><ul><ul><li>Increases “bad” cholesterol </li></ul></ul><ul><li>Recommendation: </li></ul><ul><ul><li>Less than 10% of total Calorie intake </li></ul></ul>
  15. 16. MUFAs <ul><li>Food source: primarily plant </li></ul><ul><ul><li>Canola, olive and peanut oils, avocados </li></ul></ul><ul><li>Health consequence: </li></ul><ul><ul><li>Decrease “bad” cholesterol, increase “good” cholesterol </li></ul></ul><ul><li>Recommendation: </li></ul><ul><ul><li>10% or more of total Calorie intake (no more than 30% if other fats not eaten) </li></ul></ul>
  16. 17. PUFAs <ul><li>Food source: primarily plant </li></ul><ul><ul><li>Corn, soybean, sunflower, safflower oils </li></ul></ul><ul><li>Health consequence: </li></ul><ul><ul><li>Decrease “bad” and “good” cholesterol </li></ul></ul><ul><li>Recommendation: </li></ul><ul><ul><li>10% of total Calorie intake </li></ul></ul><ul><li>Essential fatty acids: </li></ul><ul><ul><li>Alpha-linolenic acid (an omega-3) and linoleic acid (an omega-6) </li></ul></ul>
  17. 18. Thinking Time <ul><li>Which of the 3 classes of fatty acids is considered “bad fat” or is the most unhealthy for the cardiovascular system? </li></ul><ul><li>Which of the 3 classes of fatty acids provides the 2 essential fatty acids? </li></ul><ul><li>Which of the 3 classes of fatty acids should we consume most? </li></ul>
  18. 19. Hydrogenation <ul><li>PUFAs can be hydrogenated to produce a more shelf-stable, solid product </li></ul><ul><li>By-product = trans fatty acids </li></ul><ul><li>Increase “bad” cholesterol </li></ul>
  19. 20. Sterols <ul><li>Cholesterol </li></ul><ul><ul><li>Not fat </li></ul></ul><ul><ul><li>Not an essential nutrient </li></ul></ul><ul><ul><li>Normal functions in the body: </li></ul></ul><ul><ul><ul><li>Precursor for bile acids/salts </li></ul></ul></ul><ul><ul><ul><li>Cell membrane component </li></ul></ul></ul><ul><ul><ul><li>Hormones: testosterone, progesterone, estrogen, vitamin D </li></ul></ul></ul>
  20. 21. Essential Fatty Acids <ul><li>Alpha-linolenic acid, linoleic acid </li></ul><ul><li>1-2% of total energy intake from EFA enough </li></ul><ul><ul><li>Sources: plant oil, whole grains, some vegetables </li></ul></ul><ul><li>EFA deficiency: </li></ul><ul><ul><li>Flaky/itchy skin, diarrhea, infections, retarded growth and wound healing, anemia, poor vision </li></ul></ul>
  21. 22. Long-chain Omega-3 vs. Omega-6 <ul><li>Omega-3 FA (fish, canola oil, walnuts, flax seed, enriched foods) derivatives: </li></ul><ul><ul><li>Decrease blood clotting </li></ul></ul><ul><ul><li>Decrease inflammation </li></ul></ul><ul><ul><li>Vasodilation </li></ul></ul><ul><ul><li>Lower TGs </li></ul></ul><ul><ul><li>Calm smooth muscle </li></ul></ul><ul><ul><li>Decrease pain w/ rheumatoid arthritis </li></ul></ul><ul><ul><li>May help w/ some behavioral disorders and depression </li></ul></ul><ul><li>Omega-6 FA derivatives: </li></ul><ul><ul><li>Increase blood clotting </li></ul></ul><ul><ul><li>Increase inflammation </li></ul></ul><ul><ul><li>Vasoconstriction </li></ul></ul><ul><ul><li>Excite contractions in smooth muscle </li></ul></ul>
  22. 23. Heart Disease and Lipids Lipoproteins, “Good” vs. “Bad” Cholesterol, Atherosclerosis
  23. 24. Fig. 5.13
  24. 25. Fig. 5.12
  25. 26. Lipoproteins, cont. <ul><li>Chylomicron – lipoP carrier for dietary fat, cholesterol, and fat-soluble vitamins </li></ul><ul><ul><li>Absorbed in the lymphatic system, dumps into the circulatory system </li></ul></ul><ul><ul><li>Lipoprotein lipase enzyme on inside wall of blood vessels causes chylomicrons (and other lipoproteins) to release TGs and fatty acids for cells to absorb and use/store </li></ul></ul>
  26. 27. Lipoproteins, cont. <ul><li>VLDL </li></ul><ul><ul><li>Similar to chylomicrons but consist of lipids and cholesterol packaged by the liver during the fasted state </li></ul></ul><ul><ul><li>Become depleted of TGs and fatty acids because of lipoP lipase  LDL </li></ul></ul>
  27. 28. Lipoproteins, cont. <ul><li>LDL </li></ul><ul><ul><li>Primarily cholesterol core </li></ul></ul><ul><ul><li>Attaches to LDL receptors on cells, taken into cells, phospholipids and proteins recycled, cholesterol used to make bile, hormones, etc……. UNLESS ……. </li></ul></ul>
  28. 29. Lipoproteins, cont. <ul><li>Oxidative damage of LDL by free radicals    heart disease </li></ul><ul><li>If LDL continues to circulate, is susceptible to oxidative damage </li></ul><ul><li>“ Consumed” by special white blood cell phages ( scavenger cells )  become large and sluggish  attach to and bury into artery walls  tissue damage  inflammation, clotting, calcium cap = atherosclerosis </li></ul><ul><li>Atherosclerotic plaque build-up increases risk of occluding arteries  decreased oxygen flow  heart attack, stroke, pulmonary embolism, deep vein thrombosis </li></ul>
  29. 30. Fig. 5.16
  30. 31. Factors that Encourage Atherosclerosis <ul><li>LDL (high amount, small particle) </li></ul><ul><li>Smoking </li></ul><ul><li>Diabetes </li></ul><ul><li>HTN </li></ul><ul><li>Viral and bacterial infections </li></ul><ul><li>Blood vessel inflammation </li></ul>
  31. 32. Antioxidants <ul><li>May protect LDL from oxidative damage by free radicals by “ quenching ” them </li></ul><ul><li>Fruits, vegetables </li></ul><ul><li>Vitamins C, E, A </li></ul><ul><li>Caution with iron </li></ul>
  32. 33. Lipoproteins, cont. <ul><li>HDL </li></ul><ul><ul><li>Mostly protein by weight </li></ul></ul><ul><ul><li>Produced by liver </li></ul></ul><ul><ul><li>Picks up cholesterol from dead and dying cells  takes to liver to be turned into bile </li></ul></ul><ul><li>Factors affecting HDL levels: </li></ul><ul><ul><li>Gender </li></ul></ul><ul><ul><li>MUFA intake </li></ul></ul><ul><ul><li>Exercise </li></ul></ul>
  33. 34. Factors that Reduce LDL <ul><li>Low saturated fat intake </li></ul><ul><li>Increased soluble fiber intake </li></ul><ul><li>Plant sterols/stannols </li></ul><ul><li>MUFA/PUFA </li></ul>

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