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Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
Lipids ch5
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Lipids ch5

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

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