Essential fatty acid

Essential fatty acids, or EFAs, are fatty acids that cannot be constructed within an organism from other components (generally all references are to humans) by any known chemical pathways; and therefore must be obtained from the diet. The term refers to those involved in biological processes, and not fatty acids which may just play a role as fuel. As many of the compounds created from essential fatty acids can be taken directly in the diet, it is possible that the amounts required in the diet (if any) are overestimated. It is also possible they can be underestimated as organisms can still survive in nonideal, malnourished conditions.

There are two families of EFAs: omega-3 and omega-6. Fats from each of these families are essential, as the body can convert one omega-3 to another omega-3, for example, but cannot create an omega-3 from scratch. They were originally designated as Vitamin F when they were discovered as essential nutrients in 1923. In 1930, work by Burr, Burr and Miller showed that they are better classified with the fats than with the vitamins.