The effect of folate and vitamin B12 supplementation on homocysteine concentrations: a study in hemodialysis patients

Background: Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. The frequency of hyperhomocysteinemia is higher in hemodialysis (HD) patients than the general population. The objective of this study is to assess the efficacy of high-dose folic acid supplementation with and without vitamin B12 on lowering plasma total homocysteine (tHcy) concentrations in HD patients. Methods: Thirty-six HD patients at Imam Hossein Hospital, Tehran, Iran, who had been given folic acid supplements (5 mg/d) for at least 3 months before, were enrolled in this clinical trial. Subjects were also checked for other inclusion and exclusion criteria. The subjects were divided randomly into four groups and underwent two months of supplementation as follows: 5 mg/d oral folic acid + placebo in group one, 5 mg/d oral folic acid + vitamin B12 (1 mg/d orally) in group two, 15 mg/d oral folic acid + placebo in group three and 15 mg/d oral folic acid + vitamin B12 (1 mg/d orally) in group four. Concentrations of plasma tHcy and serum folic acid and vitamin B12 were measured at baseline and after the supplementation period. Dietary intake of patients was also determined during the supplementation period.Results: Of the folic acid supplemented patients, 27.8% had normal levels of tHcy at baseline and 72.2% had hyperhomocysteinemia. After the supplementation period, plasma tHcy increased by 1.35% in group one and decreased by 6.99%, 14.54% and 30.09% in groups two, three and four respectively. Changes in plasma tHcy and serum vitamin B12 were only significant in group four; however, no significant changes were seen for serum folic acid. The percentage of subjects reaching normal levels of plasma tHcy was 5.6 fold higher in group four than in the reference group. Conclusions: Supplementation with 15 mg/d folic acid together with 1 mg/d oral vitamin B12 is more effective in reducing tHcy levels in HD patients