Lipids

Functions

1. Tissue structure/function

2. Cell membrane

3. Energy source

4. Sense of satiety

5. Insulation

Triglyceride structure

Glycerol head, 3 fatty acid tails

Essential fatty acids (EFA)

Fatty acids that humans cannot synthesize; obtained through diet.

EFA structure

Long-chain-polyunsaturated fatty acids from linoleic/linolenic acid

EFA types

Omega-3 and Omega-6 fatty acids. (The body can produce Omega-9 fatty acids on its own)

Degree of saturation with H atoms

Saturated, monounsaturated, polysaturated

Saturated fats

Each carbon atom from fatty acid carries max amount of H atoms. Unhealthy; contribute to atherosclerosis. 5-10% of daily calories.

Egg yolks, whole milk, cream, ice cream.

Monounsaturated fats

Fatty acids with one hydrogen missing in its carbon atom chains. Lower LDLs; more healthy. 20% of daily calories.

Olive oil, avocados, nuts.

Polyunsaturated fats

Fatty acids with multiple hydrogen atoms missing along the carbon chains. Produce Omega-3, which lower heart disease risk and Omega-6 fatty acids. 10% of daily calories.

Fish oils, sunflower oil, corn oil.

Trans-fatty acids (TFA)

H atoms are added to monounsaturated/polyunsaturated fatty acids. Increase LDL and heart disease risk.

Hydrogenated fats

Polyunsaturated fats turned into saturated fats by hydrogenation to produce semisolid product, like margarine. Increase LDLs.

Cholesterol functions

Synthesis of bile, sex hormones, vitamin D.

Cholesterol sources

Egg yolk, fatty meats, cream, whole milk.

Cholesterol risks

Heart disease and atherosclerosis due to hypercholesterolemia and plaque buildup.

Fat digestion

Bile and lipase reduces lipids to fatty acids and glycerol in small intestine.

Lipoprotein function

Water-soluble fat carriers in blood.

Chylomicrons

First and largest lipoprotein. (high in triglycerides, delivers to cells)

VLDLs

Made by liver to transport lipids to cells. Pickup cholesterol and become LDLs as they lose triglycerides.

LDLs

Carry blood cholesterol to cells. (Bad cholesterol)

HDLs

Carry cholesterol from cells to liver for excretion. (Good cholesterol)

Metabolism location

Liver

Lecithin

Helps transport and emulsify fat in bloodstream.

Fat alternatives

Olestra, Simplesse, Oatrim,

Deficiency symptoms

Eczema, retarded growth, weight loss