ABSTRACT
The term ‘‘essential fatty acids’’ (EFAs) applies to those fatty acids that are necessary for human health and required in the diet. There are two different types of EFA deficiencies characterized by a lack of either omega-6 (o6) fatty acids or o3 fatty acids. Both o3 and o6 EFAs originate from plants and photosynthetic algae, and thus, are found throughout the food chain. The two best known o6 EFAs are linoleic acid (LA; 9Z, 12Z-octadecadienoic acid) and arachidonic acid (AA; 5Z, 8Z, 11Z, 14Z-eicosatetraenoic acid). The most common o3 EFAs are a-linolenic acid (ALA; 9Z, 12Z, 15Z-octadecatrienoic acid), eicosapentaenoic acid (EPA; 5Z, 8Z, 11Z, 14Z, 17Z-eicosapentaenoic acid), and docosahexaenoic acid (DHA; 4Z, 7Z, 10Z, 13Z, 16Z, 19Z-docosahexaenoic acid). The average intake of o6 EFAs in the United States is about 7 energy% (en%) with a ratio of almost 8 : 1 o6 EFA=o3 3 EFA. Linoleic acid and AA serve as precursors for the formation by cells of oxygenated fatty acid products called eicosanoids. At least some of the requirements for o6 EFA can be accounted for by eicosanoids. Those derived from AA promote inflammatory responses and thrombosis. There are arguments that significant decreases in inflammatory and cardiovascular diseases would occur were the ratio of the intake of o6 EFA=o3 3 EFA reduced to less than 4.0, which would decrease the formation of eicosanoids.
