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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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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)
FATTY ACIDS • Organic acids – chains of carbon and hydrogen • Acid group – COOH • Methyl group – CH3
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
SATURATION • Saturated • Mono-unsaturated • Polyunsaturated • Affects physical state – liquid or solid • Biological effect
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
ESSENTIAL FATTY ACIDS • OMEGA-6Linoleic (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
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
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
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
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
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
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
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
ABSORPTION Triglycerides + Cholesterol + = LIPOPROTEINS Phospholipids + Proteins
LIPOPROTEINS • Transport lipids • Blood lipid profile • Made in liver and small intestine • Made of triglycerides, phospholipids, cholesterol, protein water solubility
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
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
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
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
MODIFIABLE Hypercholesterolemia Hypertension Smoking Physical Inactivity Diabetes Mellitus Low LDL Obesity FIXED Family history Age Gender Menopausal females without hormonal replacement CORONARY RISK FACTORS
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
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”
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
STEP DIETS • NCEP-National Cholesterol Education Program • Age 20 and abovetotal 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
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 VLDLdec LDL, TG, ^ HDL • Probucol (Lorelco) - ^ LDL excretion, • Genfibrozil (Lopid) – dec TG, ^ HDL, dec LDL • Lovastatin (Mevacor) – dec Chol synthesis, dec LDL
FAT FUNCTIONS • BODY Provides energy – 9 kcals/gram Insulates Protects organs (shock absorber) • DIET Fat soluble vitamins Flavor, aroma, tenderness Slows digestion, satiety, fullness