EFFECTS OF FOLIC-ACID AND COMBINATIONS OF FOLIC-ACID AND VITAMIN-B-12ON PLASMA HOMOCYSTEINE CONCENTRATIONS IN HEALTHY, YOUNG-WOMEN

Background: Elevated plasma homocysteine concentrations are considered to be a risk factor for vascular disease and fetal malformations such as neural tube defects. Recent studies have shown that plasma homocys teine can be lowered by folic acid in amounts corresponding to 1-2 tim es the recommended dietary allowance. Preliminary evidence indicates t hat vitamin B-12 may be beneficial when included in supplements or in a food-fortification regimen together with folic acid. Objective: We a imed to compare the homocysteine-lowering potential of a folic acid su pplement with that of 2 supplements containing different doses of vita min B-12 in addition to folic acid. Design: Female volunteers of child bearing age (n = 150) received a placebo for 4 wk followed by a 4-wk t reatment with either 400 mu g folic acid, 400 mu g folic acid + 6 mu g vitamin B-12, or 400 mu g folic acid + 400 mu g vitamin B-12. Results : Significant reductions (P < 0.001) in plasma homocysteine were obser ved in all groups receiving vitamin treatment. The effect observed wit h the combination of folic acid + 300 mu g vitamin B-12 (total homocys teine, -18%) was significantly larger than that with a supplement cont aining folic acid alone (total homocysteine, -11%) (P < 0.05). Folic a cid in combination with a low vitamin B-12 dose (6 mu g) affected homo cysteine as well(-15%). Conclusions: These results suggest that the ad dition of vitamin B-12 to folic acid supplements or enriched foods max imizes the reduction of homocysteine and may thus increase the benefit s of the proposed measures in the prevention of vascular disease and n eural tube defects.