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LIPIDS

LIPIDS. THE LIPID FAMILY. ORGANIC COMPOUNDS INSOLUBLE IN WATER INCLUDE: TRIGLYCERIDES PHOSPHOLIPIDS STEROLS. TRIGLYCERIDES. GLYCEROL BACKBONE (CHO)  GLUCOSE ALL ALIKE –”BACKBONE” OF TRIGLYCERIDE FATTY ACIDS ENERGY (BETA OXIDATION). GLYCEROL BACKBONE.

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LIPIDS

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  1. LIPIDS

  2. THE LIPID FAMILY • ORGANIC COMPOUNDS • INSOLUBLE IN WATER • INCLUDE: TRIGLYCERIDES PHOSPHOLIPIDS STEROLS

  3. TRIGLYCERIDES • GLYCEROL BACKBONE (CHO)  GLUCOSE ALL ALIKE –”BACKBONE” OF TRIGLYCERIDE • FATTY ACIDS ENERGY (BETA OXIDATION)

  4. GLYCEROL BACKBONE

  5. CONDENSATION – GLYCEROL AND FATTY ACIDS

  6. MIXED TRIGLYCERIDE

  7. FATTY ACIDS • Organic acids – chains of carbon and hydrogen • Acid group – COOH • Methyl group – CH3

  8. PROPERTIES OF FATTY ACIDS

  9. CHAIN LENGTH • Most are even number of carbons • Short chain = 4-6 carbons; milk, butter • Medium chain = 8-12 carbons; coconut oil and synthetic medium chain triglycerides • Long chain = 14-30 carbons with 16-18 most common; animal and plant sources

  10. SATURATION • Saturated • Mono-unsaturated • Polyunsaturated • Affects physical state – liquid or solid • Biological effect

  11. COMPARISON OF DIETARY FATS

  12. ESSENTIAL FATTY ACIDS • Body cannot manufacture – necessary for body functions • Conditionally essential – inadequate precursors • Need 4% of Kcals from EFA • Lack of: skin irritation dehydration growth failure infections liver changes visual problems

  13. ESSENTIAL FATTY ACIDS • OMEGA-6Linoleic (18:2n6) found in vegetable oils *Arachidonic (20:4n6) from linoleic, egg yolk, beef liver • OMEGA-3 Linolenic (18:3n3) found in leafy vegetables * EPA and *DHA Eicosapentaenoic Acid Docosahexaenoic Acid from linolenic, fish, seafood

  14. OMEGA FATTY ACIDS

  15. BENEFITS OF EPA & DHA • Lowers serum cholesterol and triglycerides • Lowers tendency for blood to clot • EPA  regulates blood pressure • Increases synthesis of immune substances • Recommend – fish 2 times/week • No fish oil capsules

  16. OMEGA-3 FATTY ACIDS IN FISH

  17. MEDIUM CHAIN FATTY ACIDS • MCT = Medium Chain Triglycerides • Synthetic fats and fatty acids (8-10 carbons) • Used with poor digestion and malabsorption • Easily digested by intestinal lipase • Absorbed without bile acids • Transport  portal vein liver without being resynthesized to triglycerides • Used in some enteral formulas • Not palatable

  18. PHOSPOLIPIDS • Glycerol backbone • Two fatty acids • Phosphorus containing unit in place of 3rd fatty acid • Important part of cell membrane constituents • Water soluble and fat soluble • Fatty acids move across lipid membranes into watery fluids • Allow fat soluble substances to pass in and out of cells

  19. PHOSPHOLIPID STRUCTURE

  20. PHOSPHOLIPID-LECITHIN

  21. PHOSPHOLIPIDS • Found naturally abundant Eggs, liver, soybeans, wheat germ, peanuts • Used as emulsifiers Food processing Body – keep other fats suspended in blood • Should be ~ 5% of lipids in diet • WATCH HEALTH CLAIMS - LECITHIN

  22. STEROLS - CHOLESTEROL • Composed of C, H, O atoms • Arranged in rings • Variety of side chains • Present in ALL animal fats, NOT vegetable, plant fats • Sources: Dietary (300-500 mg/ day) Liver manufactures 600-1500 mg/day

  23. CHOLESTEROL

  24. CHOLESTEROL • Necessary for formation of essential substances: * steroid hormones * bile salts * cell membranes * myelin * vit D sythesis * adrenal hormones • Dietary cholesterol is NOT a significant contributor to serum cholesterol • More important Saturated Fatty Acids and Total fat

  25. Fat Digestion

  26. FAT ABSORPTION Glycerol Absorbed into Short & Medium  blood at portal Chain Fatty Acids vein to liver Monoglycerides &  Micelles (Intestinal wall) Long Chain Fatty Acids Reassembled into TRIGLYCERIDES

  27. EMULSIFICATION OF FAT

  28. HYDROLYSIS

  29. ABSORPTION Triglycerides + Cholesterol + = LIPOPROTEINS Phospholipids + Proteins

  30. TYPICAL LIPOPROTEIN

  31. LIPOPROTEINS • Transport lipids • Blood lipid profile • Made in liver and small intestine • Made of triglycerides, phospholipids, cholesterol, protein  water solubility

  32. CHYLOMICRON • From dietary fat • Intestinal cell wall • Transports lipids to muscle and fat cells  broken down by lipoprotein lipase • Remnants to the liver to be dismantled

  33. VLDL – VERY LOW DENSITY LIPOPROTEINS • Lipoprotein synthesized by liver • Triglycerides, cholesterol made from non-dietary sources (endogenous), carbohydrates, proteins, fats • Greatest percent of lipids  triglycerides

  34. LDL-LOW DENSITY LIPOPROTEIN • Remnant of VLDL – triglycerides pulled out • More dense than VLDL • Less lipids but more cholesterol • Separated to build hormones, cell walls, smooth muscles • Gathers cholesterol from lipoproteins and bloodstream  deposits body cell • Plaque formation  arterial wall • Removed from circulation by liver

  35. HDL-HIGH DENSITY LIPOPROTEIN • Scavenger of cholesterol – removes from arterial walls • Competes with LDL for receptor sites to prevent plaque formation • Liver makes HDL to transport • Cholesterol and phospholipids made by cells back to liver for recycling or disposal • LDL/HDL ratio important in heart disease

  36. LIPOPROTEINS COMPARED

  37. TYPES OF CHOLESTEROL

  38. HOW TO HAVE A HEART ATTACK

  39. MODIFIABLE Hypercholesterolemia Hypertension Smoking Physical Inactivity Diabetes Mellitus Low LDL Obesity FIXED Family history Age Gender Menopausal females without hormonal replacement CORONARY RISK FACTORS

  40. HEART DISEASE • High LDL • Low HDL • HDL-LDL RATIO • Total Fat Intake • Lab Goals: Total Cholesterol = <200 mg/dl Triglycerides = <150mg/dl LDL = <130 mg/dl ^ risk >160 HDL = >60 mg/dl ^ risk < 35 LDL/HDL ratio <3.0 (Best 2.5) 160/35 = 4.5 ^ risk 130/60 = 2.1 low risk

  41. HDL:LDL RATIO

  42. ATHEROSCLEROSIS

  43. LIPID PROFILE

  44. WHERE FAT IS AT! • Middle  increased risk of ^ blood pressure, DM, ^ serum cholesterol, ^ CVD “Apple shape” – Android (male) • Arms, thighs, buttocks  lower risk, “Pear shape” – Gynecoid (female) “Pear shape” more desirable than “apple”

  45. WHERE FAT IS • Waist:Hip ratio • At risk for obesity related problems if women >0.8 men > 0.95 • Waist: Hip ratio is waist circumference divided by hip circumference in either inches or centimeters

  46. STEP DIETS • NCEP-National Cholesterol Education Program • Age 20 and abovetotal chol & HDL every 5 years: IF total Chol >240mg/dl and evidence of CHD • Check LDL IF total Chol = 200-239mg/dl & HDL <35mg/dl • Before drug therapy – for 6 months * decrease saturated fat * decrease cholesterol intake * adjust weight (decrease caloric intake & increase physical activity • Post menopausal HRT to decrease LDL

  47. STEP DIETS

  48. DRUG THERAPY FOR HYPERLIPIDEMIA • Should be 6 months after diet therapy • Bile Acid Sequestrants (cholestyramine, colestipol) Causes binding of bile acid in gut Liver pulls more cholesterol to manufacture more bile • Nicotinic Acid dec VLDLdec LDL, TG, ^ HDL • Probucol (Lorelco) - ^ LDL excretion, • Genfibrozil (Lopid) – dec TG, ^ HDL, dec LDL • Lovastatin (Mevacor) – dec Chol synthesis, dec LDL

  49. FAT FUNCTIONS • BODY Provides energy – 9 kcals/gram Insulates Protects organs (shock absorber) • DIET Fat soluble vitamins Flavor, aroma, tenderness Slows digestion, satiety, fullness

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