Two dietary essential fatty acids linoleic acid (LA) and alpha-linolenic acid (ALA) have 18 carbons. LA is a member of omega-6 family with two double bonds (C18:2) and ALA is a member of omega-3 family with three double bonds (C18:3). Both of these fatty acids (LA and ALA) are converted in the body to have more double bonds and increased number of carbons. LA is converted to arachidonic acid (AA) with 20 carbons and 4 double bonds (20:4) and ALA is converted to eicosapentaenoic acid (EPA) which has 20 carbons and 5 double bonds (20:5). EPA can be further converted to docosahexaenoic acid (DHA) consisting of 22 carbons and 6 double bonds (22:6).