Folic Acid Fortification Ameliorates Hyperhomocysteinemia Caused by a Vitamin B6-Deficient Diet Supplemented with L-Methionine

Vitamin B-6 (B-6) deficiency affects homocysteine metabolism, and this leads to hyperhomocysteinemia. In this study, we examined i) the effects of B-6-deficiency and graduated levels of dietary methionine on homocysteine metabolism, and ii) the effects of fortified folate on homocysteine metabolism. In experiment 1, Wistar male rats were fed a control or a B-6-deficient diet supplemented with L-methionine at a level of 3, 6, or 9 g/kg of diet for 5 weeks. The resulting plasma homocysteine levels in the B-6-deficient groups increased in relation to the increase in dietary methionine level. Next, in experiment 2, rats were fed a control, B-6-deficient, or folate enriched (10 mg pteroylmonoglutamic acid/kg) B-6-deficient diet containing L-methionine at 9 g/kg for 5 weeks. Although the B-6-deficient diet induced hyperhomocysteinemia, folate fortification ameliorated the plasma homocysteine concentration. Overall, our results indicate that folate fortification ameliorates the hyperhomocysteinemia induced by B-6 deficiency and supplemental methionine intake.