Folic Acid–Based Multivitamin Therapy to Prevent Stroke The Jury Is Still Out

There is a large body of observational and laboratoryevidence suggesting but not proving that increasing plasma concentrations of total homocysteine (tHcy) is a causal risk factor for atherothromboembolic ischemic stroke and other vascular events.1–9 Recent publication of the results of the landmark Vitamins in Stroke Prevention (VISP) Trial is the first evidence from a large randomized controlled trial (RCT) of the effect of lowering tHcy via folic acid–based multiple B vitamin supplementation on the incidence of “hard ” clinical events, such as recurrent stroke, in patients with recent ischemic stroke.10,11 In contrast to what was expected from the epide-miological evidence, the VISP Trial did not identify a significant treatment effect of lowering tHcy by vitamin therapy on recurrent stroke, coronary events, or death, despite confirming a consistent and graded association betwee