The importance of folic acid.J Gend Specif Med. 1999 May-Jun; 2(3):24-8.JG
Folic acid is necessary for cell development; for the metabolism of specific biochemical reactions in the body, such as the conversion of homocysteine to methionine; and for the metabolism of specific anticonvulsant drugs. Folic acid has an interrelationship with vitamin B12. A deficiency of folate increases the risk of NTDs, as well as contributing to hyperhomocystinemia, a condition associated with increased cardiovascular disease and NTDs. For the prevention of NTDs, it is recommended that a woman of childbearing age consume a daily folate intake of 400 micrograms; however, the average dietary folate intake is half that amount, and the FDA folate fortification of cereal grains adds only 100 micrograms daily. The woman in her childbearing years does not meet the recommendation with dietary and food fortification. Periconceptional folic acid supplementation is essential, because the neural tube closes 23 to 27 days after conception. Therefore, a multiple vitamin containing folic acid is the practical solution at present if the food fortification is not increased. The bioavailability of folate in the vitamin preparation is approximately double that of dietary folate. Most preparations contain 400 micrograms of folic acid, and if the woman took a multiple vitamin (400 micrograms of folate) in addition to her diet (230 micrograms of folate), she would not exceed 1000 micrograms (1 mg) daily, which is considered the upper limit of daily folate ingestion by dietary fortification and supplementation before the masking of vitamin B12 becomes a concern. However, in this group of patients, pernicious anemia is rare. Regarding cardiovascular disease in men and women, there are no long-term studies showing the benefit of folic acid in reducing the homocysteine level. At present, there are only estimations. However, they should not be ignored. Although it is not the current standard of practice, adding a multiple vitamin containing folic acid to the regimen of men and women starting anticonvulsant medication should be considered in order to prevent the folate lowering observed with such commonly used drugs as PHT and carbamazepine. Women in childbearing years should be on a folic acid supplement when taking an anticonvulsant drug. In general, it appears that all men and women would benefit from increased folate intake. This can be accomplished through vitamin supplementation when there is compliance. However, if the food fortification for folate is increased in the future, then the issue of vitamin supplementation will have to be readdressed.