Since linoleic acid has 18 carbon atoms and 2 double bonds, it is usually represented in shorthand as C18:2, ω-6. Linoleic acid (18 carbons with 2 double bonds) and arachidonic acid (20 carbons with 4 double bonds) belong to the omega(ω)-6 group of fatty acids, since the first double bond, counting from the methyl end of the molecule, occurs at carbon number 6.

Arachidonic acid is also required by the body but can be synthesized from linoleic acid, which is abundant in oils from corn, soybeans, and safflower seeds. Linoleic acid is classified as an essential nutrient, since the body requires it but cannot synthesize it. Monounsaturated fatty acids (MUFAs), such as oleic acid, contain one double bond per molecule, whereas polyunsaturated fatty acids (PUFAs), such as linoleic acid, contain more than one. Other animal and vegetable fats contain predominantly longer-chain SFAs (more than 14 carbons in length) and are found chiefly in meats, butterfat, and some vegetable oils. Short- and medium-chain saturated fatty acids (SFAs) (4 to 12 carbons in length) are found in milk fat, palm oil, and coconut oil. The number of carbons in the chain varies, and the compound may be saturated (containing no double bonds) or unsaturated (containing one or more double bonds). They also contribute satiety, flavor, and palatability to the diet.įatty acids generally consist of a straight alkyl chain, terminating with a carboxyl group. They are important in the diet as energy sources and as sources of essential fatty acids and fat-soluble vitamins, which tend to associate with fats. Lipids that are important to our discussion include fats and oils (triglycerides or triacyglycerols), fatty acids, phospholipids, and cholesterol.įats and oils are esters of glycerol and three fatty acids.

Lipids are compounds that are insoluble in water but are soluble in organic solvents such as ether and chloroform.

Girl Oil by Grace P. Fong