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CH 5: The Lipids. Lipids include…. Fats Butter, lard, margarine… Oils Plant oils - Corn oil, olive oil, peanut oil… Cholesterol Found in animal sources of fat Dairy, egg yolk, butter, fatty meats.. . Recommended Lipid Intake. 20-35 % daily kcal from fats (TG)

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lipids include
Lipids include….
  • Fats
    • Butter, lard, margarine…
  • Oils
    • Plant oils - Corn oil, olive oil, peanut oil…
  • Cholesterol
    • Found in animal sources of fat
      • Dairy, egg yolk, butter, fatty meats..
recommended lipid intake
Recommended Lipid Intake
  • 20-35 % daily kcal from fats (TG)
      • Maximum 10% from saturated fats
      • Some say maximum 10% from polyunsaturated fats
      • Minimum 20% calories from fats
      • Limit intake of trans fats
  • Maximum 300 mg cholesterol per day
      • No or lower cholesterol intake is fine/good
introduction to lipids
Introduction to Lipids
  • Lipids – water insoluble component of cells
    • Called hydrophobic
    • Made of the elements:
      • Carbon
      • Hydrogen
      • Oxygen
      • Phosphorus (in phospholipids only)
introduction to lipids5
Introduction to Lipids

Classes of lipids:

  • Fatty acids (FA)
    • May be saturated or unsaturated
  • Triglycerides (TG) - the fats we eat
    • 9 kcal/gram
  • Phospholipids
    • Also 9 kcal/gram
  • Sterols
    • Not caloric
fatty acids
Fatty Acids
  • Fatty Acids - Long hydrocarbon chains with an acid head (pg 168)
    • Carbon chains differ in:
      • Length - most are 4-24 carbons long
      • Number and type of double bonds
fatty acids7
Fatty Acids
  • Saturated Fatty Acids
    • All carbon to carbon single bonds
      • Chain is saturated with hydrogens
    • Chain is relatively straight
  • Unsaturated Fatty Acids
    • At least one C to C double bond present
      • Called a “point of unsaturation”
    • Double bonds kink/bend the chain
unsaturated fatty acids
Unsaturated Fatty Acids
  • Monousaturated FA (MUFA)
    • One C to C double bond
  • Polyunsaturated (PUFA)
    • More than one C to C double bond
omega 3 and omega 6 fa
Omega-3 and Omega-6 FA
  • An omega-3 fatty acid - double bond starting on the 3rd carbon from the “methyl end” (shown in green).
  • An omega-6 fatty - double bond starting on the 6th carbon from the “methyl end”.
hydrogenation reaction
Hydrogenation Reaction
  • Hydrogenation reaction adds hydrogens to double bonds to convert them to single bonds
    • TG may be partially or fully hydrogenated.
  • Partially hydrogenated TG
    • Some of double bonds saturated (made single bonds)
      • As a result oils become ___________
    • The remaining double bonds are converted from cis to trans form
      • Cis form is the naturally occurring form
      • Trans FA are associated with health risks
  • Fully hydrogenated TG
    • All double bonds are saturated
      • As a result oils become solids (stick margarine)
    • Converts an unsaturated oil to a saturated fat
      • Fully hydrogenated fats have the same health issues as natural sources of sat’d fats
  • TG – chemical nature
    • 3 carbon backbone (called glycerol) with 3 fatty acids (FA) attached (page 171)
    • The chemical nature of the attached fatty acids determines the physical properties of the TG and its storage properties
  • Back to TG - Glycerol with 3 FA attached
    • FA attached may differ
    • Nature of FA impacts properties of the TG
    • Page 170

Fatty Acid #1

Fatty Acid #2

Fatty Acid #3

saturated tg
Saturated TG
  • TG with primarily saturated fatty acids attached
    • Solids at room temperature (fats)
      • Shorter the chain the softer the TG
    • Primarily from animal sources
    • More stable than TG w/ unsaturated FA
      • Store better
    • Saturated FA are associated w/ health risks
saturated tg sources
Saturated TG Sources
  • Food Sources Saturated Fats
    • Butter, cream, milk, cheese
    • Red meat
    • Coconut and palm oil – plant sources of saturated fats
    • Chicken - mixture of sat’d and unsat’dfats
      • Much of chicken fat is in the skin
unsaturated tg
Unsaturated TG
  • TG with primarily unsaturated FA
    • Liquids at room temperature (oils)
    • Primarily from plant sources
    • Double bonds are reactive
      • Therefore plant oils react with oxygen and go rancid easily
unsaturated tg sources
Unsaturated TG Sources
  • Sources of Unsaturated Fats
    • Monounsaturated
      • Olive oil, canola oil, peanut oil
    • Polyunsaturated
      • Corn oil, soybean oil, sunflower oil…..
essential fatty acids
Essential Fatty Acids
  • 2 essential fatty acids
    • Omega-3 FA – linolenic acid
      • May lower cholesterol and risk of heart disease, hypertension, ?cancer, ?arthritis
      • Good food sources: fish, soy, nuts, many oils
    • Omega-6 FA – linoleic acid
      • Food sources are vegetable oils and poultry
  • Function: structural component of all cell membranes
  • Structure:
    • Glycerol backbone (3 carbon) with 2 fatty acids attached and one phosphate group
    • Attached to phosphate group is some other group
  • 9 kcal/gram
  • Best known phospholipid is lecithin
    • Supplements are NOT needed
      • Can cause GI distress, loss of appetite
    • Liver makes phospholipids for the body
  • Food sources:
    • Eggs (yolk only)
    • Liver
    • Soybean
    • Wheat germ
    • Peanuts
  • Structure: 4 linked carbon rings with side chains
  • Examples of sterols (we make in body)
    • Cholesterol
    • Vitamin D
    • Bile salts
    • Sex hormones
digestion of lipids
Digestion of Lipids
  • Digest TG to:
    • Glycerol, fatty acids, and monoglycerides
  • Absorb:
    • Glycerol and short chain FA into capillaries
    • Longer chain FA and monoglycerides into lacteals (complicated process)
digestion of lipids31
Digestion of Lipids
  • Small amount of chemical digestion occurs in mouth and stomach
    • Infants have an enzyme that begins digestion of TG found in milk – in mouth
    • Adults make a small amount of gastric lipase
      • Begins digestion of TG in ______
digestion of lipids32
Digestion of Lipids
  • Small Intestine
    • Bile emulsifies fats (physical digestion)
    • Pancreatic and SI lipases remove FA from TG and phospholipids
      • Digestion produces:
      • Fatty acids, glycerol, monoglycerides
      • Sterols do not need digestion
  • Glycerol and short/medium chain FA
    • Absorbed into the capillaries
    • Go directly to the liver
  • Long chain FA and monoglycerides
    • Form micelles
    • Micelles are absorbed into SI cells
    • In SI cells TG are remade!
    • The newly made TG attach to protein carriers to form chlyomicrons – page 157
    • Chylomicrons are absorbed into lacteals
  • Chylomicrons – lipoproteins
    • Travel through lymph and enter blood in chest
    • Travel through the heart and then body
      • Enzymes break off fatty acids from TG and deliver them to cells for energy or storage as TG
    • Chylomicron remnants are then delivered to the liver

In the liver

  • Liver breaks down remaining TG and remakes them!
    • Liver also makes cholesterol and other TG
  • These TG and cholesterol are packaged with proteins to make VLDL
    • Very low density lipoproteins
  • VLDL enters blood
  • VLDL delivers cholesterol and fatty acids to needy cells
    • Density goes up as the fats leave the transport protein
  • VLDL becomes LDL as it loses FA
    • Low density lipoprotein
    • LDL is high in cholesterol
    • LDL circulates in blood delivering cholesterol to cells
  • LDL
    • “Bad” cholesterol
    • Contributes to plaques when cholesterol “falls off” the LDL and is deposited on artery walls
    • Plaques narrow arteries
      • Raises blood pressure
      • Increases risk of blood clots and heart attacks
  • HDL
    • High density lipoprotein
    • HDL transports cholesterol and other lipids back to liver for disposal
      • Can pick up cholesterol from plaques
      • Good cholesterol
  • Maximum level of intake recommended
    • 300 mg/day
    • Make all we need, so no intake is fine
  • Food Sources – all animal (no plant sources)
    • Egg yolk
    • Dairy (unless fat removed as in skim milk)
    • Meat, poultry
  • Blood levels
    • Goal: total cholesterol < 200 mg/dL (know this one)
    • Other recommendations (do not need to know)
      • LDL < 100 mg/dL
      • HDL > 60 mg/dL
      • LDL:HDL ratio to be less than 5 for men and less than 4.5 for women
      • Triglycerides < 150 mg/dL
lowering cholesterol levels
Lowering Cholesterol Levels
  • Reduce intake of:
    • Saturated fats
    • Trans fatty acids
    • Cholesterol
    • Sugars (if sugar sensitive)
  • Increase intake of:
    • soluble fibers (oats and legumes)
    • fish
lowering cholesterol levels45
Lowering Cholesterol Levels
  • Moderate alcohol intake
  • Exercise – aerobic may be best
  • Lose weight

FYI - Estrogen lowers cholesterol levels

Therefore, cholesterol levels often go up in postmenopausal women.

genetics matter male with a healthy weight and active lifestyle but family history of heart disease
Genetics MatterMale with a healthy weight and active lifestyle, but family history of heart disease
functions of fats in the body
Functions of Fats in the Body
  • Source of energy
  • Thermal insulation
  • Protect and supports organs
    • Fats hold some organs in place
  • Use to make all cells
  • Use to make important substances
    • E.g. sex hormones, bile……
review fat sources
Review Fat Sources
  • Saturated Fats
  • Monounsaturated Fats
    • olive, canola and peanut oil and avocados.
  • Polyunsaturated Fats
    • vegetable oils (safflower, sesame, soy, corn and sunflower), nuts and seeds.
    • Trans Fatty Acids
  • Cholesterol
review health aspects fats
Review Health Aspects Fats
  • Saturated Fats
  • Trans Fatty Acids
  • Cholesterol
  • Monounsaturated Fats
  • Polyunsaturated Fats
health effects and recommended intakes of lipids
Health Effects and Recommended Intakes of Lipids
  • Health Effects of Lipids
    • Benefits from Omega-3 Fats
      • Beneficial effects in reducing risk of heart disease and stroke
      • Food sources include vegetable oils (canola, soybean and flaxseed), walnuts and flaxseeds, and fatty fish (mackerel, salmon, and sardines).
        • Need to avoid fish with high levels of mercury

© 2008 Thomson - Wadsworth

health effects and recommended intakes of lipids52
Health Effects and Recommended Intakes of Lipids
  • Health Effects of Lipids
    • Balance Omega-6 and Omega-3 Intakes
      • Eat more fish (2 3-oz. portions per week) and less meat.
      • Bake, broil or grill the fish.
      • Select healthy oils – in moderation
      • Supplements are not the answer.

© 2008 Thomson - Wadsworth