CH 5: The Lipids. Lipids include…. Fats Butter, lard, margarine… Butter, lard, margarine… ...

CH 5: The LipidsCH 5: The Lipids

Lipids include….Lipids include….

FatsFats Butter, lard, margarine…Butter, lard, margarine…

OilsOils Plant oils - Corn oil, olive oil, peanut oil…Plant oils - Corn oil, olive oil, peanut oil…

CholesterolCholesterol Found in animal sources of fatFound in animal sources of fat

• Dairy, egg yolk, butter, fatty meats.. Dairy, egg yolk, butter, fatty meats..

Functions of Fats in the BodyFunctions of Fats in the Body

1.1. Source of energySource of energy

2.2. Thermal insulationThermal insulation

3.3. Protect and supports organs Protect and supports organs • Fats hold some organs in placeFats hold some organs in place

4.4. Use to make all cellsUse to make all cells

5.5. Use to make important substancesUse to make important substances• E.g. sex hormones, bile, vitamin D……E.g. sex hormones, bile, vitamin D……

6.6. Fatty foods contain fat soluble vitaminsFatty foods contain fat soluble vitamins

Recommended Lipid IntakeRecommended Lipid Intake

20-35 % daily kcal from fats (TG)20-35 % daily kcal from fats (TG)• Maximum 10% from saturated fatsMaximum 10% from saturated fats• Some say maximum 10% from polyunsaturated Some say maximum 10% from polyunsaturated

fatsfats• Minimum 20% calories from fatsMinimum 20% calories from fats• Limit intake of trans fatsLimit intake of trans fats

Maximum 300 mg cholesterol per dayMaximum 300 mg cholesterol per day• No or lower cholesterol intake is fine/goodNo or lower cholesterol intake is fine/good

Introduction to LipidsIntroduction to Lipids

Lipids – water insoluble component of Lipids – water insoluble component of cellscells Called hydrophobicCalled hydrophobic Made of the elements: Made of the elements:

• CarbonCarbon• HydrogenHydrogen• OxygenOxygen• Phosphorus (in phospholipids only)Phosphorus (in phospholipids only)

Introduction to LipidsIntroduction to Lipids

Classes of lipids:Classes of lipids: Fatty acids (FA)Fatty acids (FA)

• May be saturated or unsaturatedMay be saturated or unsaturated Triglycerides (TG) - the fats we eatTriglycerides (TG) - the fats we eat

• 9 kcal/gram9 kcal/gram PhospholipidsPhospholipids

• Also 9 kcal/gramAlso 9 kcal/gram SterolsSterols

• Not caloricNot caloric

Fatty AcidsFatty Acids

Fatty Acids - Long hydrocarbon chains Fatty Acids - Long hydrocarbon chains with an acid head (pg 168)with an acid head (pg 168)

Carbon chains differ in:Carbon chains differ in:• Length - most are 4-24 carbons longLength - most are 4-24 carbons long• Number and type of double bondsNumber and type of double bonds


Saturated Fatty AcidsSaturated Fatty Acids All carbon to carbon single bondsAll carbon to carbon single bonds

• Chain is Chain is saturatedsaturated with hydrogens with hydrogens Chain is relatively straightChain is relatively straight

Unsaturated Fatty AcidsUnsaturated Fatty Acids At least one C to C double bond presentAt least one C to C double bond present

• Called a “point of unsaturation”Called a “point of unsaturation” Double bonds kink/bend the chainDouble bonds kink/bend the chain

Unsaturated Fatty AcidsUnsaturated Fatty Acids

Monousaturated FA (MUFA)Monousaturated FA (MUFA) One C to C double bondOne C to C double bond

Polyunsaturated (PUFA)Polyunsaturated (PUFA) More than one C to C double bondMore than one C to C double bond

Omega-3 and Omega-6 FAOmega-3 and Omega-6 FA

An omega-3 fatty acid - double bond starting An omega-3 fatty acid - double bond starting on the 3on the 3rdrd carbon from the “methyl end” carbon from the “methyl end” (shown in green).(shown in green).

An omega-6 fatty - double bond starting on An omega-6 fatty - double bond starting on the 6the 6thth carbon from the “methyl end”. carbon from the “methyl end”.

Cis and Trans Fatty AcidsCis and Trans Fatty Acids

Hydrogenation ReactionHydrogenation Reaction

Hydrogenation reaction adds hydrogens to Hydrogenation reaction adds hydrogens to double bonds to convert them to single double bonds to convert them to single bondsbonds TG may be partially or fully hydrogenated.TG may be partially or fully hydrogenated.

HydrogenationHydrogenation

Partially hydrogenated TGPartially hydrogenated TG Some of double bonds saturated (made single Some of double bonds saturated (made single

bonds)bonds)• As a result oils become ___________As a result oils become ___________

The remaining double bonds are converted The remaining double bonds are converted from from ciscis to to transtrans form form• Cis form is the naturally occurring formCis form is the naturally occurring form• Trans FA are associated with health risksTrans FA are associated with health risks

HydrogenationHydrogenation

Fully hydrogenated TGFully hydrogenated TG All double bonds are saturatedAll double bonds are saturated

• As a result oils become solids (stick margarine)As a result oils become solids (stick margarine) Converts an unsaturated oil to a saturated fatConverts an unsaturated oil to a saturated fat

• Fully hydrogenated fats have the same health Fully hydrogenated fats have the same health issues as natural sources of sat’d fatsissues as natural sources of sat’d fats

TriglyceridesTriglycerides

TG – chemical natureTG – chemical nature 3 carbon backbone (called glycerol) with 3 3 carbon backbone (called glycerol) with 3

fatty acids (FA) attached (page 171)fatty acids (FA) attached (page 171)

The chemical nature of the attached fatty The chemical nature of the attached fatty acids determines the physical properties of acids determines the physical properties of the TG and its storage propertiesthe TG and its storage properties

TGTG

Back to TG - Glycerol with 3 FA attachedBack to TG - Glycerol with 3 FA attached

FA attached may differFA attached may differ Nature of FA impacts properties of the TGNature of FA impacts properties of the TG Page 170Page 170

Fatty Acid #1

Fatty Acid #2

Fatty Acid #3

TriglycerideTriglyceride

Saturated TGSaturated TG

TG with primarily saturated fatty acids TG with primarily saturated fatty acids attachedattached Solids at room temperature (fats)Solids at room temperature (fats)

• Shorter the chain the softer the TGShorter the chain the softer the TG Primarily from animal sourcesPrimarily from animal sources More stable than TG w/ unsaturated FAMore stable than TG w/ unsaturated FA

• Store betterStore better Saturated FA are associated w/ health risks Saturated FA are associated w/ health risks

Saturated TG SourcesSaturated TG Sources

Food Sources Saturated FatsFood Sources Saturated Fats Butter, cream, milk, cheeseButter, cream, milk, cheese Red meatRed meat Coconut and palm oil – plant sources of Coconut and palm oil – plant sources of

saturated fatssaturated fats Chicken - mixture of sat’d and unsat’d fatsChicken - mixture of sat’d and unsat’d fats

• Much of chicken fat is in the skinMuch of chicken fat is in the skin

Unsaturated TGUnsaturated TG

TG with primarily unsaturated FATG with primarily unsaturated FA Liquids at room temperature (oils)Liquids at room temperature (oils) Primarily from plant sourcesPrimarily from plant sources Double bonds are reactiveDouble bonds are reactive

• Therefore plant oils react with oxygen and go Therefore plant oils react with oxygen and go rancid easilyrancid easily

Unsaturated TG SourcesUnsaturated TG Sources

Sources of Unsaturated FatsSources of Unsaturated Fats MonounsaturatedMonounsaturated

• Olive oil, canola oil, peanut oilOlive oil, canola oil, peanut oil PolyunsaturatedPolyunsaturated

• Corn oil, soybean oil, sunflower oil…..Corn oil, soybean oil, sunflower oil…..

Essential Fatty AcidsEssential Fatty Acids

2 essential fatty acids 2 essential fatty acids Omega-3 FA – linolenic acidOmega-3 FA – linolenic acid

• May lower cholesterol and risk of heart disease, May lower cholesterol and risk of heart disease, hypertension, ?cancer, ?arthritishypertension, ?cancer, ?arthritis

• Good food sources: Good food sources: fishfish, soy, nuts, many oils, soy, nuts, many oils Omega-6 FA – linoleic acidOmega-6 FA – linoleic acid

• Food sources are vegetable oils and poultryFood sources are vegetable oils and poultry

Fats in FoodsFats in Foods

Review page 173Review page 173

PhospholipidsPhospholipids

Function: structural component of all cell Function: structural component of all cell membranesmembranes

Structure:Structure: Glycerol backbone (3 carbon) with 2 fatty Glycerol backbone (3 carbon) with 2 fatty

acids attached and one phosphate group acids attached and one phosphate group Attached to phosphate group is some other Attached to phosphate group is some other

group group


9 kcal/gram9 kcal/gram Don’t need to eat phospholipidsDon’t need to eat phospholipids

• liver makes phospholipids for the bodyliver makes phospholipids for the body

Best known phospholipid is lecithinBest known phospholipid is lecithin Supplements are NOT neededSupplements are NOT needed

• Can cause GI distress, loss of appetiteCan cause GI distress, loss of appetite


Food sources:Food sources: Eggs yolkEggs yolk Liver and other organ meatsLiver and other organ meats SoybeanSoybean Wheat germWheat germ PeanutsPeanuts

SterolsSterols

Structure: 4 linked carbon rings with side Structure: 4 linked carbon rings with side chainschains

Examples of sterols Examples of sterols (we make in body)(we make in body) CholesterolCholesterol Vitamin DVitamin D Bile saltsBile salts Sex hormonesSex hormones

Cholesterol in FoodsCholesterol in Foods

See page 174See page 174 Note all are animal sourcesNote all are animal sources Leading sources of cholesterol in US dietLeading sources of cholesterol in US diet

Eggs (yolk)Eggs (yolk) Beef productsBeef products Dairy products – cheese, whole milk, ice Dairy products – cheese, whole milk, ice

creamcream Chicken Chicken

Overview Digestion & Overview Digestion & AbsorptionAbsorption

Digest TG to:Digest TG to: Glycerol, fatty acids, and monoglyceridesGlycerol, fatty acids, and monoglycerides

Absorb:Absorb: Glycerol and short chain FA (12 C or less) Glycerol and short chain FA (12 C or less)

absorbed into capillaries absorbed into capillaries liver liver Longer chain FA and monoglycerides first Longer chain FA and monoglycerides first

absorbed into SI cell, TG remade, then absorbed into SI cell, TG remade, then absorbed into lacteals (complicated process)absorbed into lacteals (complicated process)

Digestion of Lipids - detailDigestion of Lipids - detail

Small amount of chemical digestion occurs Small amount of chemical digestion occurs in mouth and stomachin mouth and stomach Infants have an enzyme that begins digestion Infants have an enzyme that begins digestion

of TG found in milk – in mouthof TG found in milk – in mouth Adults make a small amount of gastric lipaseAdults make a small amount of gastric lipase

• Begins digestion of TG in ______Begins digestion of TG in ______

Digestion of LipidsDigestion of Lipids

Small IntestineSmall Intestine Bile emulsifies fats (physical digestion)Bile emulsifies fats (physical digestion) Pancreatic and SI lipases remove FA from TG Pancreatic and SI lipases remove FA from TG

and phospholipidsand phospholipids• Digestion produces:Digestion produces:• Fatty acids, glycerol, monoglyceridesFatty acids, glycerol, monoglycerides

• Sterols do not need digestionSterols do not need digestion

AbsorptionAbsorption

Glycerol and short/medium chain FA, 12 C Glycerol and short/medium chain FA, 12 C or less:or less: Absorbed into the capillariesAbsorbed into the capillaries Go directly to the liverGo directly to the liver

AbsorptionAbsorption

Long chain FA and monoglyceridesLong chain FA and monoglycerides Form Form micelles micelles Micelles are absorbed into SI cellsMicelles are absorbed into SI cells In SI cells TG are remade!In SI cells TG are remade! The newly made TG attach to protein carriers The newly made TG attach to protein carriers

to form chlyomicrons – page 181to form chlyomicrons – page 181 Chylomicrons are absorbed into lactealsChylomicrons are absorbed into lacteals

TransportTransport

Chylomicrons – lipoproteinsChylomicrons – lipoproteins Primarily TG with protein carrierPrimarily TG with protein carrier Travel through lymph and enter blood in chestTravel through lymph and enter blood in chest Travel through the heart and then bodyTravel through the heart and then body

• Enzymes break off fatty acids from TG and deliver Enzymes break off fatty acids from TG and deliver them to cells for energy or storage as TGthem to cells for energy or storage as TG

Chylomicron remnants are then delivered to Chylomicron remnants are then delivered to the liverthe liver

TransportTransport

In the liver – In the liver – pages 181/182pages 181/182 Liver breaks down remaining TG and remakes Liver breaks down remaining TG and remakes

them! them! • Liver also makes cholesterol and other TGLiver also makes cholesterol and other TG

These TG and cholesterol are packaged with These TG and cholesterol are packaged with proteins to make proteins to make VLDLVLDL• Very low density lipoproteins – mostly TGVery low density lipoproteins – mostly TG

TransportTransport

VLDL enters bloodVLDL enters blood VLDL delivers fatty acids to needy cellsVLDL delivers fatty acids to needy cells

Density goes up as the fats leave the Density goes up as the fats leave the transport proteintransport protein

Relative amount of cholesterol goes up ad TG Relative amount of cholesterol goes up ad TG leave VLDLleave VLDL

TransportTransport

VLDL becomes LDL as it loses FAVLDL becomes LDL as it loses FA Low density lipoproteinLow density lipoprotein LDL is high in cholesterolLDL is high in cholesterol LDL circulates in blood delivering cholesterol LDL circulates in blood delivering cholesterol

to cellsto cells

TransportTransport

LDLLDL ““Bad” cholesterolBad” cholesterol Contributes to plaques when cholesterol “falls Contributes to plaques when cholesterol “falls

off” the LDL and is deposited on artery wallsoff” the LDL and is deposited on artery walls Plaques narrow arteriesPlaques narrow arteries

• Raises blood pressureRaises blood pressure• Increases risk of blood clots and heart attacksIncreases risk of blood clots and heart attacks

TransportTransport

HDLHDL High density lipoproteinHigh density lipoprotein HDL transports cholesterol and other lipids HDL transports cholesterol and other lipids

back to liver for disposalback to liver for disposal• Can pick up cholesterol from plaquesCan pick up cholesterol from plaques• Good cholesterolGood cholesterol

CholesterolCholesterol

Maximum level of intake recommendedMaximum level of intake recommended 300 mg/day300 mg/day Make all we need, so no intake is fineMake all we need, so no intake is fine

Food Sources – all animal Food Sources – all animal (no plant sources)(no plant sources) Egg yolkEgg yolk Dairy (unless fat removed as in skim milk)Dairy (unless fat removed as in skim milk) Meat, poultryMeat, poultry

CholesterolCholesterol

Blood levelsBlood levels Goal: total cholesterol < 200 mg/dL Goal: total cholesterol < 200 mg/dL (know this one)(know this one)

Other recommendations Other recommendations (do not need to know)(do not need to know)

• LDL < 100 mg/dLLDL < 100 mg/dL• HDL > 60 mg/dLHDL > 60 mg/dL• LDL:HDL ratio to be less than 5 for men and less LDL:HDL ratio to be less than 5 for men and less

than 4.5 for womenthan 4.5 for women• Triglycerides < 150 mg/dLTriglycerides < 150 mg/dL

Lowering Cholesterol LevelsLowering Cholesterol Levels

1.1. Reduce intake of:Reduce intake of:• Saturated fatsSaturated fats• Trans fatty acidsTrans fatty acids• CholesterolCholesterol• Sugars (if sugar sensitive)Sugars (if sugar sensitive)

2.2. Increase intake of:Increase intake of:• soluble fibers (oats and legumes)soluble fibers (oats and legumes)• fishfish

Lowering Cholesterol LevelsLowering Cholesterol Levels

3.3. Moderate alcohol intake Moderate alcohol intake

4.4. Exercise – aerobic may be bestExercise – aerobic may be best

5.5. Lose weightLose weight

FYI - Estrogen lowers cholesterol levels FYI - Estrogen lowers cholesterol levels

Therefore, cholesterol levels often go up in Therefore, cholesterol levels often go up in postmenopausal women.postmenopausal women.

Weight Loss and CholesterolWeight Loss and Cholesterol

YearYear 20032003 20042004

WeightWeight 235 pounds235 pounds 195 pounds195 pounds

Total Total cholesterolcholesterol

302302 157157

HDLHDL 6868 5353

LDLLDL 193193 8888

TriglyceridesTriglycerides 206206 9797

Genetics MatterGenetics MatterMale with a healthy weight and active lifestyle, but Male with a healthy weight and active lifestyle, but

family history of heart diseasefamily history of heart disease

Initial Initial valuesvalues

After Dietary After After Dietary After

Changes Meds.Changes Meds.

Total Total chol.chol.

242242 214 151214 151

HDLHDL 4040 36 3636 36

LDLLDL 157157 132 74132 74

TGTG 223223 230 203230 203

Review Fat SourcesReview Fat Sources

Saturated FatsSaturated Fats Monounsaturated FatsMonounsaturated Fats

olive, canola and peanut oil and avocadosolive, canola and peanut oil and avocados.. Polyunsaturated FatsPolyunsaturated Fats

vegetable oils (safflower, sesame, soy, corn and vegetable oils (safflower, sesame, soy, corn and sunflower), nuts and seeds.sunflower), nuts and seeds.

Trans Fatty AcidsTrans Fatty Acids CholesterolCholesterol

Review Health Aspects FatsReview Health Aspects Fats

Saturated FatsSaturated Fats Trans Fatty AcidsTrans Fatty Acids CholesterolCholesterol

Monounsaturated FatsMonounsaturated Fats Polyunsaturated FatsPolyunsaturated Fats


Health Effects and Recommended Health Effects and Recommended Intakes of LipidsIntakes of Lipids

Health Effects of LipidsHealth Effects of Lipids Benefits from Omega-3 FatsBenefits from Omega-3 Fats

• Beneficial effects in reducing risk of heart disease Beneficial effects in reducing risk of heart disease and strokeand stroke

• Food sources include vegetable oils (canola, Food sources include vegetable oils (canola, soybean and flaxseed), walnuts and flaxseeds, soybean and flaxseed), walnuts and flaxseeds, and fatty fish (mackerel, salmon, and sardines).and fatty fish (mackerel, salmon, and sardines).

Need to avoid fish with high levels of mercuryNeed to avoid fish with high levels of mercury


Health Effects and Recommended Health Effects and Recommended Intakes of LipidsIntakes of Lipids

Health Effects of LipidsHealth Effects of Lipids Balance Omega-6 and Omega-3 IntakesBalance Omega-6 and Omega-3 Intakes

• Eat more fish (2 3-oz. portions per week) and less Eat more fish (2 3-oz. portions per week) and less meat.meat.

• Bake, broil or grill the fish.Bake, broil or grill the fish.• Select healthy oils – in moderationSelect healthy oils – in moderation• Supplements are not the answer.Supplements are not the answer.

CH 5: The Lipids. Lipids include…. Fats Butter, lard, margarine… Butter, lard, margarine… ...

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