Homocysteine-lowering trials for prevention of cardiovascular events: a review of the design and power of the large randomized trials.

BACKGROUND: Dietary supplementation with folic acid and vitamin B12 lowers blood homocysteine concentrations by about 25% to 30% in populations without routine folic acid fortification of food and by about 10% to 15% in populations with such fortification. In observational studies, 25% lower homocy...