Gamma Linolenic Acid Oils

Essential fatty acids (EFAs) can be defined by classic definition, which defines EFAs as the fatty acids that are required for proper functioning of cells, but the body cannot synthesize them and, therefore, must be supplied by diet. According to this definition, there are only two EFAs: linolenic acid (LA, C18:2, n-6) and alpha-linolenic acid (ALA, C18:3, n-3). The functional definition of EFAs includes the fatty acids that can correct the symptoms produced by elimination of all EFAs from the diet. According to this definition, LA, gamma linolenic acid (GLA, C18:3, n-6), and arachidonic acid (AA, C20:4, n-6) are EFAs of n-6 family (1, 2). Gamma linolenic acid (cis-6, cis-9, cis-12-octadecatrienoic acid) is an 18-carbon polyunsaturated fatty acid containing three double bonds. It is produced in the body from desaturation of LA by the reaction catalyzed by enzyme delta-6-desaturase (D-6-D) (Figure 1). GLA is rapidly elongated to DGLA by elongase enzyme. Cats do not have this enzyme; hence, they cannot synthesize GLA and subsequent metabolites from LA (3). Therefore, cats must eat a meat-based diet to obtain longer chain metabolites of LA (DGLA, AA). DGLA can be acetylated and incorporated into membrane phospholipids. A small amount can be converted into AA, and this