HNSC 3310 Macronutrient handout (lipids)

Fatty acids

carbon chain with methyl end and carboxyl end; vary according to

• Chain length: 2-6 Carbons = short; 8-12 carbons = medium; >14 carbons = long

• Saturation: saturated (SFA or SAT), mono-unsaturated (MUFA) or polyunsaturated (PUFA)

• Position of double bonds:

• cis or trans (natural or synthetic production)

• n-3, n-6 or n-9 (same as omega-3, omega-6 and omega-9)

Neutral lipids

fatty acids on glycerol backbone

• Monoglyceride (MG; 1 fatty acid + glycerol)

• Diglyceride (DG; 2 fatty acids + glycerol)

• Triglyceride (TG: 3 fatty acids + glycerol)

• Note: Carbons on glycerol backbone designated as C-1, C-2 (middle) and C-3

• Draw the structure of a 2-monoglyceride

Phospholipids

glycerol + 2 fatty acids + phosphate + nitrogen containing molecule (choline, serine, inositol or ethanolamine)

• e.g. phosphatidylcholine = lecithin

• PL make up >50% of cell membranes

• Usually a saturated FA (C16-C18) at C-1 of glycerol

• Usually a PUFA (C16-C20) at C-2 of glycerol

Non-glycerol containing lipids

• Sphingolipids (e.g. nerves)

• Alcohols

• Waxes (esters of fatty acids and higher alcohol, e.g. cholesterol ester = cholesterol + fatty acid)

• Terpenes (plant pigments eg. lycopene, carotenoids, chlorophyll; or isoprenoids e.g. Vitamins A, D, E and K, Coenzyme Q)

• Steroids e.g. cortisone, testosterone, estrogen, bile acids, cholesterol, Vitamin D

Lipids combined with other compounds

• Glycolipids (CHO + lipid)

• Lipoproteins (lipid + protein) e.g. LDL, HDL

Synthetic lipids

• Medium-chain triglycerides (MCT: SFA with chain length of 6-12 carbons; naturally occurring or produced commercially)

• Structured lipids (put FA at specific position in glycerol backbone)

Note: various Fat replacers (may be CHO, protein or fat based): not readily absorbable, but imitate the texture and mouth-feel of fat in food