The effect of dietary modification on polyunsaturated fatty acid biosynthesis and metabolism

The essential fatty acids (EFAs) α-linolenic acid (ALA) and linoleic acid can be converted to their respective longer-chain polyunsaturated fatty acids (PUFA) via the same metabolic pathway. Consequently, the flux of LA and ALA is influenced by the absolute and relative amounts of these EFAs in the diet. Total fat intake also influences the activity of the PUFA synthesis pathway by altering the level of transcription of genes that encode key enzymes. Detail rodent feeding studies show that increasing dietary LA decreases incorporation of ALNA into cell membranes and conversion to eicosapentaenoic (EPA) and doocosahexaenoic (DHA) acids. The findings of the limited number of studies of the impact of dietary fat on PUFA synthesis in humans are in general agreement with those in rodents. The highest conversion of ALA to EPA and DHA is achieved by increasing ALA intake with decreased intake of LA and total PUFA.