The Lipids

Introduction to Lipids  Lipids – water insoluble component of cells Hydrophobic Hydrophobic Made of the elements: Made of the elements: CarbonCarbon HydrogenHydrogen OxygenOxygen Phosphorus (in phospholipids only)Phosphorus (in phospholipids only)

Introduction to Lipids Classes of lipids: Triglycerides and fatty acids Triglycerides and fatty acids Triglycerides are the fats we eatTriglycerides are the fats we eat 9 kcal/gram9 kcal/gram Phospholipids Phospholipids Also 9 kcal/gramAlso 9 kcal/gram Steroids Steroids

Intake  Recommended levels of intake: % daily kcal from fats (triglycerides) % daily kcal from fats (triglycerides) Maximum 10% from saturated fatsMaximum 10% from saturated fats Maximum 300 mg cholesterol per day Maximum 300 mg cholesterol per day No or lower cholesterol intake is fine/goodNo or lower cholesterol intake is fine/good

Triglycerides  3 carbon backbone (called glycerol) with 3 fatty acids (FA) attached Nature of the attached fatty acid determines the properties of the triglycerideNature of the attached fatty acid determines the properties of the triglyceride

Triglyceride

Fatty Acids  Fatty Acids - structure Long hydrocarbon chains Long hydrocarbon chains Most are 4-24 carbons long Most are 4-24 carbons long Always an even number of carbonsAlways an even number of carbons Carbon chains differ in: Carbon chains differ in: LengthLength Points of unsaturationPoints of unsaturation

Fatty Acids  Saturated Fatty Acids All carbon to carbon single bonds All carbon to carbon single bonds Chain is saturated with hydrogensChain is saturated with hydrogens Chain is relatively straight Chain is relatively straight

Fatty Acids  Unsaturated Fatty Acids At least one C to C double bond present At least one C to C double bond present Double bonds kink/bend the chain Double bonds kink/bend the chain

Fatty Acids  Monounsaturated FA One C to C double bond One C to C double bond  Polyunsaturated More than one C to C double bond More than one C to C double bond

Triglycerides  Fatty acids may differ Nature of fatty acids impacts properties of the triglyceride Nature of fatty acids impacts properties of the triglyceride

Saturated Fats  Triglycerides with primarily saturated fatty acids: Solid Solid Primarily from animal sources Primarily from animal sources Plant sources include palm and coconut oilPlant sources include palm and coconut oil More stable than Triglycerides with unsaturated FA More stable than Triglycerides with unsaturated FA Store betterStore better Taste better!Taste better! Associated with health risksAssociated with health risks

Unsaturated Fats  Triglycerides with primarily unsaturated fatty acids are: Liquids (oils) Liquids (oils) Primarily from plant sources Primarily from plant sources Double bonds are reactive Double bonds are reactive Therefore plant oils react with oxygen and go rancid easilyTherefore plant oils react with oxygen and go rancid easily

 Food Sources Saturated Fats Butter, cream, milk, cheese Butter, cream, milk, cheese Red meat Red meat Chicken and fish are a mixture of sat’d and unsat’d fats Chicken and fish are a mixture of sat’d and unsat’d fats

 Sources of Unsaturated Fats Monounsaturated Monounsaturated Olive oil, canola oil, peanut oilOlive oil, canola oil, peanut oil Polyunsaturated Polyunsaturated Corn oil, soybean oil, sunflower oil…..Corn oil, soybean oil, sunflower oil…..

Fatty Acids  Essential Fatty Acids Omega-3 FA => double bond 3 C from the end Omega-3 FA => double bond 3 C from the end May lower cholesterol and risk of heart disease, hypertension, ?cancer, ?arthritisMay lower cholesterol and risk of heart disease, hypertension, ?cancer, ?arthritis Good food sources: fish, soy, nuts, many oilsGood food sources: fish, soy, nuts, many oils

Triglyceride

Hydrogenation  Hydrogenation reaction Adds hydrogens to double bonds Adds hydrogens to double bonds Removes “kinks” from fatty acid chains Removes “kinks” from fatty acid chains Fully hydrogenated fats have the same health issues as natural sources of saturated fatsFully hydrogenated fats have the same health issues as natural sources of saturated fats

Hydrogenation  Partially hydrogenated triglycerides Often the remaining double bonds converted from cis to trans form Often the remaining double bonds converted from cis to trans form Cis form is the naturally occurring formCis form is the naturally occurring form Trans fatty acids are associated with health risksTrans fatty acids are associated with health risks

Cis and Trans Fatty acids

Phospholipids  Function: structural component of all cell membranes  Structure: Glycerol backbone (3 carbons) with 2 fatty acids attached and one phosphate group Glycerol backbone (3 carbons) with 2 fatty acids attached and one phosphate group Attached to the phosphate group is some other group Attached to the phosphate group is some other group

Steroids  Structure: 4 linked carbon rings with side chains  Examples of steroids (we make in body) Cholesterol Cholesterol Vitamin D Vitamin D Bile salts Bile salts Sex hormones Sex hormones

Transport of lipids in Blood Stream Low density lipoprotein (LDL) Low density lipoprotein (LDL) LDL is high in cholesterol LDL is high in cholesterol LDL circulates in blood looking for cells that need cholesterol LDL circulates in blood looking for cells that need cholesterol Also picks up cholesterol from other lipoproteinsAlso picks up cholesterol from other lipoproteins

Transport  LDL “Bad” cholesterol “Bad” cholesterol Contributes to plaques when cholesterol “falls off” the LDL and is deposited on artery walls Contributes to plaques when cholesterol “falls off” the LDL and is deposited on artery walls Plaques narrow arteries Plaques narrow arteries Raises blood pressureRaises blood pressure Increases risk of blood clots and heart attacksIncreases risk of blood clots and heart attacks

Transport  HDL High density lipoprotein High density lipoprotein HDL transports cholesterol and other lipids back to liver for disposal HDL transports cholesterol and other lipids back to liver for disposal Can pick up cholesterol from plaquesCan pick up cholesterol from plaques Good cholesterolGood cholesterol

Cholesterol  Maximum level of intake recommended 300 mg/day 300 mg/day Make all we need, so no intake is fine Make all we need, so no intake is fine  Food Sources – all animal (no plant sources) Egg yolk Egg yolk Dairy (unless fat removed as in skim milk) Dairy (unless fat removed as in skim milk) Meat, poultry Meat, poultry

Lowering Cholesterol Levels 1. Reduce intake of: Saturated fats Saturated fats Trans fatty acids Trans fatty acids Cholesterol Cholesterol Sugars (if sugar sensitive) Sugars (if sugar sensitive) 2. Increase intake of: soluble fibers (oats and legumes) soluble fibers (oats and legumes) fish fish

Lowering Cholesterol Levels 3. Moderate alcohol intake 4. Exercise – aerobic may be best 5. Lose weight