Effects of vitamin B-6 on (n-3) polyunsaturated fatty acid metabolism

To investigate interactions between vitamin B-6 and fatty acid metabolism, male Wistar rats were fed a vitamin B-6 (B-B)-deficient diet consisting of 70% vitamin-free casein and 10% perilla oil [similar to 63% alpha-linolenic acid, (n-3)] for 5 wk, The amounts of linoleic acid (n-6) and arachidonic acid (n-6) in the B-6-deficient group changed only slightly compared with t hose in a pair-fed control group. The amount of linoleic acid increased and arachidonic acid decreased in the plasma total lipid fraction, and the rat ios of both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in t he B-6-deficient group were significantly lower than for the controls. The ratios of alpha-linolenic acid and EPA were higher, and DHA lower, in the B -6-deficient group than in the pair-fed control group in the total lipid as well as phospholipid fractions in liver microsomes, The activity of Delta 6-desaturase was significantly lower in the B-6-deficient group than in the pair-fed control group (similar to 64%), and acyl-CoA oxidase activity, an initial enzyme of the peroxisomal beta-oxidation pathway, was reduced by s imilar to 80% in the B-6-deficient group. These data suggest that B-6 defic iencies impair the metabolism of (n-3) PUFA from alpha-linolenic acid to EP A and DHA with the most pronounced reduction in the production of DHA.