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Vitamin supplements and cardiovascular risk: review of the randomized trials of homocysteine-lowering vitamin supplements.

A meta-analysis of 12 randomized trials of vitamin supplements to lower homocysteine levels was carried out to determine the optimal dose of folic acid required to lower homocysteine levels and to assess whether vitamin B12 or vitamin B6 had additive effects. This meta-analysis demonstrated that reductions in blood homocysteine levels were greater at higher pretreatment blood homocysteine levels and at lower pretreatment folate concentrations. After standardization for a pretreatment homocysteine concentration of 12 micromol/L and folate concentration of 12 nmol/L (approximate average concentrations for western populations), dietary folic acid reduced homocysteine levels by 25% (95% confidence interval [CI]: 23 to 28%) with similar effects in a daily dosage range of 0.5 to 5 mg… Large-scale randomized trials of such regimens are now required to determine whether lowering homocysteine levels by folic acid and vitamin B12, with or without added vitamin B6, reduces the risk of vascular disease

Dose-dependent effects of folic acid on blood concentrations of homocysteine: a meta-analysis of the randomized trials.

Folic acid deficiency has been found in people with depression and has been linked to poor response to antidepressant treatment. Homocysteine is considered a significant risk factor for cardiovascular disease and may be modified by B vitamins, including folate or derivatives. Daily doses of > or =0.8 mg folic acid are typically required to achieve the maximal reduction in plasma homocysteine concentrations produced by folic acid supplementation. Doses of 0.2 and 0.4 mg are associated with 60% and 90%, respectively, of this maximal effect. Homocysteine Lowering Trialists’ Collaboration.