The omega-3 fatty acid alpha linolenic acid (ALA) is the precursor or “parent” to the two long-chain omega 3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Walnuts contain ALA and fatty fish contain EPA and DHA. Metabolic reactions enable ALA to be converted into EPA and DHA.
While some studies have suggested that the conversion of the omega-3 fatty acid ALA to the longer-chain fatty acids, EPA and DHA, could be below 10 percent in humans, there is a potentially wide variation in the rate of conversion. Research also indicates that ALA provides health benefits independent of conversion to longer chain fatty acids.