linolenic acid

Alpha-linolenic acid (ALA), an 18-carbon omega-3 essential fatty acid, is the precursor of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA cannot be synthesized by humans and therefore must be entirely acquired from exogenous sources. Evidence for the essentiality of ALA was first provided by a study showing that ALA supplementation reversed the abnormal neurologic signs observed in a 6-year-old girl who suffered from sensory loss and visual complications. Most of the ALA is catabolized via beta-oxidation for energy generation, and a small proportion of it undergoes conversion to produce another two potent members of omega-3 PUFA family: EPA and DHA. Delta 6 desaturase (D6D) enzyme is responsible the conversion of ALA to DHA. Although not conclusive, it was suggested, that the benefits associated with ALA seem to stem mainly from EPA and DHA, and as major consequence of ALA deficiency it appears that EPA and DHA are not adequately produced. — NCATS