Chapter 5 Lipids

Triglycerides

The main form of lipid in food and the body; composed of 1 glycerol molecule bound to 3 fatty acid chains.

Phospholipids

Lipids containing a glycerol molecule, 2 fatty acids, and a phosphate group (e.g., lecithin); act as emulsifiers.

Sterols

Lipids with a complex multi-ring structure (e.g., cholesterol, vitamin D, steroid hormones).

Cholesterol

A sterol found only in animal-derived foods; essential for cell membranes, bile, and vitamin D synthesis.

HDL (High-Density Lipoprotein)

Good" cholesterol transporter; carries excess cholesterol from body tissues back to the liver for excretion.

LDL (Low-Density Lipoprotein)

"Bad" cholesterol transporter; delivers cholesterol to body tissues, elevated levels increase heart disease risk.

Bile Acids

Compounds made in the liver from cholesterol and stored in the gallbladder that emulsify fats in the intestine.

Trans Fats

Unsaturated fats containing trans double bonds formed during partial hydrogenation; raise LDL and lower HDL.

Hydrogenation

Industrial process adding hydrogen to liquid vegetable oils to make them more solid and stable against oxidation.

Digestion & Absorption Location

Occurs primarily in the small intestine, where bile emulsifies fats and pancreatic lipase breaks triglycerides into free fatty acids and monoglycerides

Linoleic Acid (Omega-6):

Found in plant oils (corn, soybean, sunflower), nuts, and seeds.

Alpha-Linolenic Acid (Omega-3):

Found in flaxseed, chia seeds, walnuts, canola oil, and fatty fish (EPA/DHA).

Functions of Lipids in the Body

High-density energy storage, organ padding, thermal insulation, precursor to hormones, cell membrane structure.

Lipids function in food

Provides flavor, aroma, texture (satiety), and carries fat-soluble vitamins (A, D, E, K).

Total Cholesterol:

< 200 mg/dL

LDL Cholesterol

< 100 mg/dL

HDL Cholesterol

Greater than or equal to 60 mg/dL

Triglycerides:

<150 mg/dL

Saturated acids identification

No double bonds; fully saturated with hydrogen atoms.

Monounsaturated (MUFA)

One double bond in the carbon chain.

Polyunsaturated (PUFA):

Two or more double bonds in the carbon chain.

Characteristics & Sources of saturated fats

Solid at room temperature; found in animal fats, butter, palm/coconut oil; increases LDL.

Characteristics of Unsaturated fats

Liquid at room temperature; found in plant oils, olive oil, avocados, nuts.

Cholesterol

Present only in animal products (egg yolks, meat, dairy, poultry).

Total Fat AMDR:

20%–35% of total daily calories.

Saturated Fat:

< 10% of daily calories (preferably < 7\%).

Trans fat intake recommendations

Keep intake as low as possible (0%).