LIPIDS. THE LIPID FAMILY ORGANIC COMPOUNDS INSOLUBLE IN WATER INCLUDE: TRIGLYCERIDES PHOSPHOLIPIDS...
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Transcript of LIPIDS. THE LIPID FAMILY ORGANIC COMPOUNDS INSOLUBLE IN WATER INCLUDE: TRIGLYCERIDES PHOSPHOLIPIDS...
LIPIDS
THE LIPID FAMILYORGANIC COMPOUNDSINSOLUBLE IN WATERINCLUDE:
TRIGLYCERIDES PHOSPHOLIPIDS STEROLS
TRIGLYCERIDESGLYCEROL BACKBONE (CHO) GLUCOSE
ALL ALIKE –”BACKBONE” OF TRIGLYCERIDEFATTY ACIDS ENERGY (BETA OXIDATION)
GLYCEROL BACKBONE
CONDENSATION – GLYCEROL AND FATTY ACIDS
MIXED TRIGLYCERIDE
FATTY ACIDSOrganic acids – chains of carbon and hydrogenAcid group – COOHMethyl group – CH3
PROPERTIES OF FATTY ACIDS
CHAIN LENGTHMost are even number of carbonsShort chain = 4-6 carbons; milk, butterMedium chain = 8-12 carbons; coconut oil and synthetic medium chain triglyceridesLong chain = 14-30 carbons with 16-18 most common; animal and plant sources
SATURATIONSaturatedMono-unsaturatedPolyunsaturated Affects physical state – liquid or solidBiological effect
COMPARISON OF
DIETARY FATS
ESSENTIAL FATTY ACIDSBody cannot manufacture – necessary for body functionsConditionally essential – inadequate precursorsNeed 4% of Kcals from EFALack of: skin irritation dehydration
growth failure infections liver changes visual
problems
ESSENTIAL FATTY ACIDSOMEGA-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
OMEGA FATTY ACIDS
BENEFITS OF EPA & DHALowers serum cholesterol and triglyceridesLowers tendency for blood to clotEPA regulates blood pressureIncreases synthesis of immune substancesRecommend – fish 2 times/weekNo fish oil capsules
OMEGA-3 FATTY ACIDS IN FISHFish 3.5oz raw Omega-3 Cholesterol
Mackeral, Atlantic 2500 mg 80
Herring, Atlantic 1600 60
Bluefish 1200 59
Salmon, Atlantic 1200 74
Tuna, white 500 47
Tuna, light 250 47
Cod, Atlantic 300 43
Shrimp 300 42
Flounder 200 46
Haddock 200 63
Sword Fish 200 39
MEDIUM CHAIN FATTY ACIDS
MCT = Medium Chain TriglyceridesSynthetic fats and fatty acids (8-10 carbons)Used with poor digestion and malabsorptionEasily digested by intestinal lipaseAbsorbed without bile acidsTransport portal vein liver without being resynthesized to triglyceridesUsed in some enteral formulasNot palatable
PHOSPOLIPIDSGlycerol backboneTwo fatty acidsPhosphorus containing unit in place of 3rd fatty acidImportant part of cell membrane constituentsWater soluble and fat solubleFatty acids move across lipid membranes into watery fluids Allow fat soluble substances to pass in and out of cells
PHOSPHOLIPID STRUCTURE
PHOSPHOLIPID-LECITHIN
PHOSPHOLIPIDSFound naturally abundant
Eggs, liver, soybeans, wheat germ, peanutsUsed as emulsifiers
Food processing Body – keep other fats suspended in blood
Should be ~ 5% of lipids in dietWATCH HEALTH CLAIMS - LECITHIN
STEROLS - CHOLESTEROLComposed of C, H, O atomsArranged in ringsVariety of side chainsPresent in ALL animal fats, NOT vegetable, plant fatsSources:
Dietary (300-500 mg/ day) Liver manufactures 600-1500 mg/day
CHOLESTEROL
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 cholesterolMore important Saturated Fatty Acids and Total fat
Fat Digestion
FAT ABSORPTIONGlycerol Absorbed into Short & Medium blood at portal Chain Fatty Acids vein to liver
Monoglycerides & Micelles (Intestinal wall)Long Chain Fatty Acids Reassembled into
TRIGLYCERIDES
EMULSIFICATION OF FAT
HYDROLYSIS
ABSORPTION Triglycerides +Cholesterol + = LIPOPROTEINSPhospholipids +Proteins
TYPICAL LIPOPROTEIN
LIPOPROTEINSTransport lipidsBlood lipid profileMade in liver and small intestineMade of triglycerides, phospholipids, cholesterol, protein water solubility
CHYLOMICRONFrom dietary fatIntestinal cell wallTransports lipids to muscle and fat cells broken down by lipoprotein lipaseRemnants to the liver to be dismantled
VLDL – VERY LOW DENSITY LIPOPROTEINS
Lipoprotein synthesized by liverTriglycerides, cholesterol made from non-dietary sources (endogenous), carbohydrates, proteins, fatsGreatest percent of lipids triglycerides
LDL-LOW DENSITY LIPOPROTEIN
Remnant of VLDL – triglycerides pulled outMore dense than VLDLLess lipids but more cholesterolSeparated to build hormones, cell walls, smooth musclesGathers cholesterol from lipoproteins and bloodstream deposits body cellPlaque formation arterial wallRemoved from circulation by liver
HDL-HIGH DENSITY LIPOPROTEINScavenger of cholesterol – removes from arterial wallsCompetes with LDL for receptor sites to prevent plaque formationLiver makes HDL to transportCholesterol and phospholipids made by cells back to liver for recycling or disposalLDL/HDL ratio important in heart disease
LIPOPROTEINS COMPARED
TYPES OF CHOLESTEROL
HOW TO HAVE A HEART ATTACK
CORONARY RISK FACTORS MODIFIABLE
HypercholesterolemiaHypertensionSmokingPhysical InactivityDiabetes MellitusLow LDLObesity
FIXEDFamily historyAgeGenderMenopausal females without hormonal replacement
HEART DISEASEHigh LDLLow HDLHDL-LDL RATIOTotal Fat IntakeLab 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
HDL:LDL RATIO
ATHEROSCLEROSIS
LIPID PROFILE
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 ISWaist:Hip ratioAt risk for obesity related problems if women >0.8 men > 0.95Waist: Hip ratio is waist circumference divided by hip circumference in either inches or centimeters
STEP DIETSNCEP-National Cholesterol Education ProgramAge 20 and abovetotal chol & HDL every 5 years:
IF total Chol >240mg/dl and evidence of CHDCheck LDL
IF total Chol = 200-239mg/dl & HDL <35mg/dlBefore 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
STEP DIETS
STEP 1 STEP 2TOTAL FAT < 30% Kcals Same
SFA <10% Kcals <7%
PUFA Max 10 Kcals Same
MUFA Remaining fat calories Same
CHOL < 300 mg daily < 200
CHO 55% Kcals Same
PROTEIN 15-20% Kcals Same
KCALS Achieve and maintain IBW Same
Promote normal growth and development
Same
DRUG THERAPY FOR HYPERLIPIDEMIA
Should be 6 months after diet therapyBile Acid Sequestrants (cholestyramine, colestipol) Causes binding of bile acid in gut
Liver pulls more cholesterol to manufacture more bileNicotinic Acid dec VLDLdec LDL, TG, ^ HDLProbucol (Lorelco) - ^ LDL excretion, Genfibrozil (Lopid) – dec TG, ^ HDL, dec LDLLovastatin (Mevacor) – dec Chol synthesis, dec LDL
FAT FUNCTIONSBODY
Provides energy – 9 kcals/gram Insulates Protects organs (shock absorber)
DIET Fat soluble vitamins Flavor, aroma, tenderness Slows digestion, satiety, fullness
FAT AS ENERGY
ADIPOSE CELLAdipose cells have lipoproteinlipase (LPL) on surface to extract triglyceridesLPL hydrolyzes Triglycerides and directs components into cell for metabolism and storage
ADIPOSE CELL
FOR ENERGYHormone sensitive lipase dismantles stored triglycerides glycerol and fatty acidsCells requiring energy break down fatty acids energy + CO2 + H2ONeeds CHOs to completely metabolizeDoes NOT provide enough energy for brain or CNSWithout CHO: Fat + fat = ketone bodies (ketosis)
HYDROGENATIONPolyunsaturated saturated fatLiquid solidAdd hydrogen at the double bondDoes not change Kcals or cholesterolDecreases rancidity: double bonds break (unstable) spoilageCIS to TRANS fatty
HYDROGENATION
CIS TO TRANS
HYDROGENATIONCIS Formation
Typical of fatty acids found in natural foods
Hydrogens on same side U-like formation
TRANS formation During hydrogenation Hydrogens on opposite sides Linear formation
Safety issues - LDL= Saturated fat diet ( HDL)
FAT SUBSTITUTESProteinamino acidsmetabolized
egg whites, milk protein, or whey protein concentrateCHO derivativeshydrolysissimpler form
oat bran (amylase)amylodextrin (dextrinase)glucose
Olestra 3 chain fatty acidHepta, hexa, & octaesters
OLEAN STRUCTURE
FAT SUBSTITUTES