Involvement of 5-methyltetrahydrofolate in the amelioration of hyperhomocysteinemia caused by vitamin B(6) deficiency and L-methionine supplementation.

We attempted to clarify the reason why folate fortification ameliorates hyperhomocysteinemia induced by vitamin B(6) deficiency. Hyperhomocysteinemia caused by vitamin B(6) deficiency significantly decreased the rat liver 5-methyltetrahydrofolate level which was significantly improved by folate fortification. This result suggests that the amelioration of hyperhomocysteinemia in response to folate supplementation had enhanced the removal of homocysteine via methionine synthase.