Efficacy of folic acid supplementation in stroke prevention: a meta-analysis

SummaryBackgroundThe efficacy of treatments that lower homocysteine concentrations in reducing the risk of cardiovascular disease remains controversial. Our aim was to do a meta-analysis of relevant randomised trials to assess the efficacy of folic acid supplementation in the prevention of stroke.MethodsWe collected data from eight randomised trials of folic acid that had stroke reported as one of the endpoints. Relative risk (RR) was used as a measure of the effect of folic acid supplementation on the risk of stroke with a random effect model. The analysis was further stratified by factors that could affect the treatment effects.FindingsFolic acid supplementation significantly reduced the risk of stroke by 18% (RR 0·82, 95% CI 0·68–1·00; p=0·045). In the stratified analyses, a greater beneficial effect was seen in those trials with a treatment duration of more than 36 months (0·71, 0·57–0·87; p=0·001), a decrease in the concentration of homocysteine of more than 20% (0·77, 0·63–0·94; p=0·012), no fortification or partly fortified grain (0·75, 0·62–0·91; p=0·003), and no history of stroke (0·75, 0·62–0·90; p=0·002). In the corresponding comparison groups, the estimated RRs were attenuated and insignificant.InterpretationOur findings indicate that folic acid supplementation can effectively reduce the risk of stroke in primary prevention.