LipidsLipids

LipidsLipids

Do not readily dissolve in waterDo not readily dissolve in water

Types of lipids:Types of lipids:– TriglyceridesTriglycerides– PhospholipidsPhospholipids– Sterols (Cholesterol)Sterols (Cholesterol)

Fats (solid) and oils (liquid)Fats (solid) and oils (liquid)– 9 kcal /gm9 kcal /gm

Chemical Forms of Common Chemical Forms of Common LipidsLipids

Fatty AcidsFatty Acids

Found in our body and foodsFound in our body and foods– In triglycerides In triglycerides

Saturated fatty acidsSaturated fatty acids– Solid formSolid form

Unsaturated fatty acidsUnsaturated fatty acids– Liquid formLiquid form

Fats are composed of both saturated Fats are composed of both saturated and unsaturated fatty acidsand unsaturated fatty acids

Fatty Acid Structure Fatty Acid Structure

omega endomega end alpha alpha endend

Degree of saturationDegree of saturation

H H H H H H H H H H H H H H H H H O

H-C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C-C-OH

H H H H H H H H H H H H H H H H H

Saturated Fatty Acid Saturated Fatty Acid StructureStructure

omega endomega end alpha endalpha end

Degree of saturation: single carbon bondDegree of saturation: single carbon bond

H H H H H H H H H H H H H H H H H O

H-C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C--C-C-OH

H H H H H H H H H H H H H H H H H

Monounsaturated Fatty Acid Monounsaturated Fatty Acid StructureStructure

omega endomega end alpha alpha endend

One double bondOne double bond

H H H H H H H H H H H H H H H O

H-C--C--C--C--C--C--C--C--C=C--C--C--C--C--C--C--C--C-OH

H H H H H H H H H H H H H H H H H

Polyunsaturated Fatty Acid Polyunsaturated Fatty Acid StructureStructure

omega endomega end alpha alpha endend

>> 2 double bonds 2 double bonds

H H H H H H H H H H H H H O

H-C--C--C--C--C--C=C--C--C=C--C--C--C--C--C--C--C--C-OH

H H H H H H H H H H H H H H H H H

Composition of Common Fats / Composition of Common Fats / OilsOils

Essential Fatty AcidsEssential Fatty Acids

Omega-3 fatty acid (alpha-linolenic acid)Omega-3 fatty acid (alpha-linolenic acid) Omega-6 fatty acid (linoleic acid)Omega-6 fatty acid (linoleic acid) Body can only make double bonds after Body can only make double bonds after

the 9th carbon from the omega endthe 9th carbon from the omega end FunctionsFunctions

– Immune function, vision, cell membrane, Immune function, vision, cell membrane, and production of hormone-like compoundsand production of hormone-like compounds

TriglyceridesTriglycerides

Most common form of fats and oils in Most common form of fats and oils in our body & in the foods we eatour body & in the foods we eat

Fatty acids attached to a glycerolFatty acids attached to a glycerol

Triglycerides Triglycerides

Glycerol + 3 FA’s Triglyceride +Glycerol + 3 FA’s Triglyceride +

3 H3 H2200

PhospholipidsPhospholipids

Built on a glycerol backboneBuilt on a glycerol backbone Contains phosphorus compound(s)Contains phosphorus compound(s) Found in bodyFound in body Synthesized by the body as neededSynthesized by the body as needed

Functions of PhospholipidsFunctions of Phospholipids

Component of cell membraneComponent of cell membrane EmulsifierEmulsifier

– Bile acidsBile acids– LecithinsLecithins– Improves food productsImproves food products

Found in wheat germ, peanuts, Found in wheat germ, peanuts, yolks, soy beans, organ meatyolks, soy beans, organ meat

SterolsSterols

Multi-ringed structureMulti-ringed structure Do not have a glycerol backboneDo not have a glycerol backbone Cholesterol is a sterolCholesterol is a sterol Waxy substanceWaxy substance Do not readily dissolve in waterDo not readily dissolve in water Found in animal foodsFound in animal foods

Functions of CholesterolFunctions of Cholesterol

Essential component of cell Essential component of cell membranemembrane

Produced by the liverProduced by the liver Found only in animal productsFound only in animal products Forms important hormonesForms important hormones

– Estrogen, testosterone, vitamin DEstrogen, testosterone, vitamin D

Precursor to bile acidsPrecursor to bile acids

Lipids in FoodsLipids in Foods

EmulsifiersEmulsifiers

Hidden FatHidden Fat

Look on the Nutrition Facts labelsLook on the Nutrition Facts labels Look on the lists of ingredientsLook on the lists of ingredients Control portion sizeControl portion size

Reduced-Fat FoodsReduced-Fat Foods

Calorie content is about the sameCalorie content is about the same Sugar is commonly added in place of Sugar is commonly added in place of

fatfat

Fat SubstitutesFat Substitutes Water Water

– Diet margarineDiet margarine Z-trim Z-trim

– Starch derivative that binds with waterStarch derivative that binds with water Fiber cellulose Fiber cellulose

– Maltrin, Stellar, OatrimMaltrin, Stellar, Oatrim Dairy-Lo Dairy-Lo

– Protein globulesProtein globules Olestra or Olean (links fatty acid to Olestra or Olean (links fatty acid to

sucrose)sucrose)– Not digestedNot digested– FDA approved for fried snack foods FDA approved for fried snack foods – Fat-soluble vitamins issueFat-soluble vitamins issue

RancidityRancidity

Decomposed oilsDecomposed oils Breakdown of the C=C bonds by Breakdown of the C=C bonds by

UV light, and/or OUV light, and/or O22

Unpleasant odor and flavorUnpleasant odor and flavor PUFA more susceptible PUFA more susceptible Limited shelf lifeLimited shelf life

Prevention of RancidityPrevention of Rancidity

HydrogenationHydrogenationAddition of vitamin EAddition of vitamin EAddition of Butylated Addition of Butylated

hydroxyanisol (BHA) and hydroxyanisol (BHA) and Butylated hydroxytolune Butylated hydroxytolune (BHT)(BHT)

Hydrogenation of Fatty Hydrogenation of Fatty AcidsAcids

Process used to solidify an oilProcess used to solidify an oil Addition of H to C=C double Addition of H to C=C double

bondsbonds Increases shelf lifeIncreases shelf life Formation of Formation of transtrans fatty acid fatty acid

– (similar to shape of saturated fatty (similar to shape of saturated fatty acid)acid)

HydrogenationHydrogenation

Cis and Cis and TransTrans Fatty Acid Fatty Acid

Excessive Excessive TransTrans Fatty Acid Fatty Acid IntakeIntake

Raises LDLRaises LDL Lowers HDLLowers HDL Increases risk for Increases risk for

cardiovascular diseasecardiovascular disease Current intake is 3%-4% of Current intake is 3%-4% of

total kcaltotal kcal Added to food labels Jan. ‘06Added to food labels Jan. ‘06

Typical Sources of Typical Sources of TransTrans Fat Fat

Minimize Intake of Minimize Intake of TransTrans Fat Fat

Limit use of hydrogenated Limit use of hydrogenated fatsfats

Limit deep-fried foodsLimit deep-fried foodsLimit high-fat baked goodsLimit high-fat baked goodsLimit use of non-dairy Limit use of non-dairy

creamerscreamers

Digestion of Fats and OilsDigestion of Fats and Oils

Digestion of Fat in the Digestion of Fat in the StomachStomach

Gastric lipaseGastric lipase – Activated by an acidic environment Activated by an acidic environment – Acts on triglycerides containing Acts on triglycerides containing

short- and medium-chain fatty short- and medium-chain fatty acidsacids

Digestion of Fat in the Small Digestion of Fat in the Small IntestineIntestine

Primary site of fat digestionPrimary site of fat digestion Hormone Cholecystokinin (CCK) Hormone Cholecystokinin (CCK)

– Stimulates release of pancreatic lipaseStimulates release of pancreatic lipase Bile acid releasedBile acid released

– Emulsifies digested fatEmulsifies digested fat Fat is broken downFat is broken down

– To monoglycerides and fatty acidsTo monoglycerides and fatty acids

Absorption of FatAbsorption of Fat

95% of dietary fat is absorbed95% of dietary fat is absorbed Diffused into the absorptive cellsDiffused into the absorptive cells Short- and medium-chain (<12 C) Short- and medium-chain (<12 C)

fatty acids fatty acids – Are water solubleAre water soluble– Enter the portal systemEnter the portal system

Long-chain fatty acids re-form into Long-chain fatty acids re-form into triglyceridestriglycerides– Not water solubleNot water soluble– Enter the lymphatic system Enter the lymphatic system

Carrying Fat in the Carrying Fat in the BloodstreamBloodstream

Water (blood) and oil (fat) are Water (blood) and oil (fat) are incompatibleincompatible

Unique system of fat transportation Unique system of fat transportation is neededis needed

Transportation of Absorbed Transportation of Absorbed Fatty AcidsFatty Acids

Re-formed into triglyceridesRe-formed into triglycerides Packaged into chylomicronsPackaged into chylomicrons Lipoprotein lipase Lipoprotein lipase

– Breaks down triglycerides in the Breaks down triglycerides in the chylomicronschylomicrons

Chylomicron remnant Chylomicron remnant – Delivered to the liverDelivered to the liver

LipoproteinsLipoproteins

Composition and Roles of Composition and Roles of LipoproteinsLipoproteins

Transportation of Transportation of Synthesized FatSynthesized Fat

Made primarily by the liverMade primarily by the liver Very-Low-Density Lipoprotein (VLDL)Very-Low-Density Lipoprotein (VLDL) Low-Density Lipoprotein (LDL)Low-Density Lipoprotein (LDL) High-Density Lipoprotein (HDL)High-Density Lipoprotein (HDL)

High-Density Lipoprotein High-Density Lipoprotein (HDL)(HDL)

Synthesized by liver and intestineSynthesized by liver and intestine High proportion of protein High proportion of protein Picks up cholesterol from dying cells Picks up cholesterol from dying cells

and other sourcesand other sources Transfers cholesterol to other Transfers cholesterol to other

lipoproteins lipoproteins Transfers cholesterol directly back to Transfers cholesterol directly back to

the liverthe liver

Benefits of (a high) HDL Benefits of (a high) HDL (level)(level)

Removes cholesterol from the Removes cholesterol from the bloodstreambloodstream

HDL may block oxidation of LDLHDL may block oxidation of LDL Reduces risk of cardiovascular Reduces risk of cardiovascular

diseasedisease Pre-menopausal women have Pre-menopausal women have

higher HDLhigher HDL

Scavenger WBC removes Scavenger WBC removes (oxidized) LDL from circulation(oxidized) LDL from circulation

Build-up of plaque on walls of the Build-up of plaque on walls of the blood vesselsblood vessels

Development of atherosclerosisDevelopment of atherosclerosis Vessel damage caused by: Vessel damage caused by:

– Smoking, diabetes, hypertension, Smoking, diabetes, hypertension, homocysteine, high LDL, infectionhomocysteine, high LDL, infection

Scavenger Cells Scavenger Cells

AntioxidantAntioxidant

Reduces oxidationReduces oxidation Slows LDL uptake by scavenger Slows LDL uptake by scavenger

cellscells

Functions of Essential Functions of Essential Fatty AcidsFatty Acids

Essential Fatty Acid- Omega-3 Essential Fatty Acid- Omega-3 (alpha-linolenic acid)(alpha-linolenic acid)

omega endomega end alpha endalpha end

1st double bond is located on the 3rd 1st double bond is located on the 3rd carbon from the omega endcarbon from the omega end

H H H H H H H H H H H H H H H H H O

H-C--C--C=C--C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH

H H H H H H H H H H H

Omega-3 Fatty AcidOmega-3 Fatty Acid

Primarily from fish oilPrimarily from fish oil Also found in canola, walnuts, Also found in canola, walnuts,

flax seeds, mussels, crab, flax seeds, mussels, crab, shrimp, and soybean oilshrimp, and soybean oil

Recommended intake of ~2 Recommended intake of ~2 servings of fish per weekservings of fish per week

Essential Fatty Acid- Omega-6 Essential Fatty Acid- Omega-6 (alpha-linoleic acid)(alpha-linoleic acid)

omega endomega end alpha endalpha end

1st double bond is located on the 6th 1st double bond is located on the 6th carbon from the omega endcarbon from the omega end

H H H H H H H H H H H H H O

H-C--C--C--C-- C--C =C--C--C=C--C--C--C--C--C--C--C--C-OH

H H H H H H H H H H H H H H H H H

Omega-6 Fatty AcidOmega-6 Fatty Acid

Found in vegetable oilsFound in vegetable oils Only need Only need

~ 2-4 tablespoons a day ~ 2-4 tablespoons a day

Health-related EffectsHealth-related Effects

Archidonic acid (Omega-6 )Archidonic acid (Omega-6 )– Increases blood clottingIncreases blood clotting– Increases inflammatory responsesIncreases inflammatory responses

DHA, EPA (Omega-3)DHA, EPA (Omega-3)– Decrease blood clottingDecrease blood clotting– Reduce heart attackReduce heart attack– Decrease inflammation Decrease inflammation – Excess may cause hemorrhagic strokeExcess may cause hemorrhagic stroke– Other possible uses: Lower triglycerides, Other possible uses: Lower triglycerides,

rheumatoid arthritis, behavioral rheumatoid arthritis, behavioral disordersdisorders

Signs and Symptoms of Signs and Symptoms of Essential Fatty Acids Essential Fatty Acids

DeficiencyDeficiency

Flaky, itchy skinFlaky, itchy skin DiarrheaDiarrhea InfectionsInfections Retarded growth and wound Retarded growth and wound

healinghealing

Functions of Fatty Acids Functions of Fatty Acids

Provide energyProvide energy Efficient storage of energyEfficient storage of energy InsulationInsulation ProtectionProtection Transport fat-soluble vitaminsTransport fat-soluble vitamins Some satietySome satiety Flavor and mouth feelFlavor and mouth feel

Recommendations for Fat Recommendations for Fat IntakeIntake

No RDA No RDA AHA recommendationsAHA recommendations

– 20-30% of total kcal from fat20-30% of total kcal from fat– 7-10% can come from saturated/7-10% can come from saturated/transtrans fat fat– 200-300 mg cholesterol/day200-300 mg cholesterol/day

Average U.S. intake:Average U.S. intake:– 33% of total kcal from fat33% of total kcal from fat– 13% of kcal from saturated fat13% of kcal from saturated fat– 180-320 mg cholesterol/day180-320 mg cholesterol/day

AHA GoalsAHA Goals

AHA RecommendationsAHA Recommendations

Advice from National Advice from National Cholesterol Education Cholesterol Education Program and Food and Program and Food and

Nutrition Board Nutrition Board Up to 35% of total kcal from fatUp to 35% of total kcal from fat Keep saturated fat, cholesterol, Keep saturated fat, cholesterol,

and and transtrans fat to a minimum fat to a minimum

Other RecommendationsOther Recommendations

Fat intake can be higher as long as Fat intake can be higher as long as saturated and saturated and transtrans fatty acid are fatty acid are minimalminimal

Eat plenty of fruits and vegetablesEat plenty of fruits and vegetables Cut down on red meatsCut down on red meats Cut down on simple sugars and Cut down on simple sugars and

refined carbohydraterefined carbohydrate Promote healthy weightPromote healthy weight Be activeBe active

Cutting the FatCutting the Fat

Road to a Heart AttackRoad to a Heart Attack

Cardiovascular DiseaseCardiovascular Disease

Myocardial infarctionMyocardial infarction Cerebrovascular diseaseCerebrovascular disease

Risk FactorsRisk Factors

Total blood cholesterol > 200 mg/dlTotal blood cholesterol > 200 mg/dl Smoking Smoking

– Increases clottingIncreases clotting– Increases expression of genetic linkIncreases expression of genetic link

Hypertension (> 139/89)Hypertension (> 139/89) DiabetesDiabetes

– Insulin increases cholesterol synthesisInsulin increases cholesterol synthesis– Guarantees development of Guarantees development of

cardiovascular diseasecardiovascular disease

Other Risk FactorsOther Risk Factors

Low HDL (< 40 mg/dl)Low HDL (< 40 mg/dl) AgeAge Family historyFamily history Blood triglycerides > 200 mg/dlBlood triglycerides > 200 mg/dl Obesity Obesity

– Fat around the waistFat around the waist– Insulin resistanceInsulin resistance

InactivityInactivity

Signs of a Heart AttackSigns of a Heart Attack

Intense, prolong chest painIntense, prolong chest pain Shortness of breathShortness of breath SweatingSweating Nausea and vomitingNausea and vomiting DizzinessDizziness WeaknessWeakness Jaw, neck, shoulder painJaw, neck, shoulder pain Irregular heartbeatIrregular heartbeat

Medical Intervention Medical Intervention

For those who experience a heart For those who experience a heart attackattack– Or have CVD or diabetesOr have CVD or diabetes

www.nhlbi.nih.gov/guidelines/cholestewww.nhlbi.nih.gov/guidelines/cholesterol/index/htmrol/index/htm

Medication to lower LDLMedication to lower LDL– Reduce cholesterol synthesis (Statins, Reduce cholesterol synthesis (Statins,

“Lipitor”)“Lipitor”)– Binds to bile acids for eliminationBinds to bile acids for elimination

Medication to lower blood triglycerides Medication to lower blood triglycerides – Reduce triglyceride synthesisReduce triglyceride synthesis

Lowering LDLLowering LDL

See your doctor to assess for other See your doctor to assess for other conditionsconditions

Reduce dietary saturated fat and Reduce dietary saturated fat and cholesterolcholesterol

Increase MUFA and PUFAIncrease MUFA and PUFA Increase dietary fiber (soluble)Increase dietary fiber (soluble)

Lowering Blood TGLowering Blood TG

Is the most diet-responsive blood Is the most diet-responsive blood lipidlipid

Avoid overeatingAvoid overeating Limit alcoholLimit alcohol Limit simple sugarsLimit simple sugars Small frequent mealsSmall frequent meals Include fish in the dietInclude fish in the diet

Other Possible MethodsOther Possible Methods

BenecolBenecol and and Take Control Take Control margarinesmargarines– Plant stanol/sterol estersPlant stanol/sterol esters– Cholesterol-lowering effectsCholesterol-lowering effects– Decrease absorption of cholesterol and Decrease absorption of cholesterol and

lower amount returning via lower amount returning via enterohepatic circulationenterohepatic circulation

– Liver takes up more cholesterol from Liver takes up more cholesterol from the bloodthe blood

Raising HDLRaising HDL

Physical activityPhysical activity At least 45 min/day, 4 days a weekAt least 45 min/day, 4 days a week Don’t smokeDon’t smoke Eat regularly Eat regularly Eat less total fatEat less total fat Moderate intake of alcohol increases Moderate intake of alcohol increases

HDL HDL