Unlike omega-3 fatty acids (ω−3) and omega-6 fatty acid (ω−6), omega-7 (ω−7) and omega−9 fatty acids (ω−9 fatty acids or n−9 fatty acids) are not classed as essential fatty acids (EFA). This is both because they can be created by the human body from unsaturated fat, and are therefore not essential in the diet, and because the lack of an omega−6 double bond keeps them from participating in the reactions that form the eicosanoids.
The three types of omega-3 fatty acids involved in human physiology are α-linolenic acid (ALA) (found in plant oils), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (both commonly found in marine oils).
Most omega-6 fatty acids in the diet come from vegetable oils, such as Linoleic acid (LA, 18:2, n−6), the shortest-chained omega−6 fatty acid. Omega-6 fatty acids are precursors to endocannabinoids, lipoxins and specific eicosanoids.
The two most common omega-7 fatty acids in nature are palmitoleic acid and vaccenic acid.
Oleic acid (olive oil) and Erucic acid (rapesed, mustard seed) are most commercially important Omega-9 fatty acids