title: Efficacy of folic acid supplementation in stroke prevention: new insight from a meta-analysis.
abstract: OBJECTIVE
  There are growing data and a continuing controversy over the efficacy of folic acid supplementation in stroke prevention. We conducted a meta-analysis based on relevant, up-to-date published randomised trials to further examine this issue.
  
  
  METHODS
  Relative risk (RR) was used to measure the effect of folic acid supplementation on risk of stroke with a fixed-effects model.
  
  
  RESULTS
  Overall, folic acid supplementation reduced the risk of stroke by 8% (n = 55,764; RR: 0.92; 95% CI: 0.86-1.00, p = 0.038). In the 10 trials with no or partial folic acid fortification (n = 43,426), the risk of stroke was reduced by 11% (0.89; 0.82-0.97, p = 0.010). Within these trials, a greater beneficial effect was observed among trials with a lower percent use of statins [≤ 80% (median); 0.77; 0.64-0.92, p = 0.005], and a meta-regression analysis also suggested a positive dose-response relationship between percent use of statins and log-RR for stroke associated with folic acid supplementation (p = 0.013). A daily dose of 0.4-0.8mg folic acid appeared to be adequate for stroke prevention in comparison with larger doses. In the remaining five trials conducted in populations with folic acid fortification (n = 12,338), folic acid supplementation had no effect on stroke risk (1.03; 0.88-1.21, 0.69).
  
  
  CONCLUSIONS
  Our analysis indicated that folic acid supplementation is effective in stroke prevention in populations with no or partial folic acid fortification. In addition, a greater beneficial effect was observed among trials with a lower percent use of statins. Our findings underscore the importance of identifying target populations that can particularly benefit from folic acid therapy.
authors.affiliation: Department of Cardiology, Peking University First Hospital, Beijing, China. huoyong@263.net.cn
authors.forename: Y
authors.initials: Y
authors.lastname: Huo
authors.forename: X
authors.initials: X
authors.lastname: Qin
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: N
authors.initials: N
authors.lastname: Sun
authors.forename: Q
authors.initials: Q
authors.lastname: Zeng
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: X
authors.initials: X
authors.lastname: Wang
mesh_terms: D000368:Aged; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006397:Hematinics / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D020521:Stroke / Q000517:prevention & control*
chemical_list: D006397:Hematinics; D005492:Folic Acid