Methods: Twelve randomized controlled trials published between 1970 and December 2007 were identified using Medline and a manual search. All 12 studies used hypertensive subjects who were supplemented with at least 5000 ìg/d of folic acid for between 2 and 16 weeks. Three separate meta-analyses were carried out using a random-effects model, and the overall effect sizes were calculated for changes in systolic and diastolic blood pressures and for changes in endothelial function as measured through the percentage of change in flow-mediated dilation.
Results: The pooled estimate of effect of folic acid supplementation on systolic and diastolic blood pressure was −2.03 mm Hg (95% confidence interval [CI], −3.63 to −0.43; P = .04) and 0.01 mm Hg (95% CI, −1.12 to 1.13; not significant), respectively. The pooled estimate of effect of folic acid supplementation on change in flow-mediated dilation was 1.61% (95% CI, 1.27 to 1.96; P = .000).
Conclusion: Based upon the studies used in this meta-analysis, supplementation with at least 5000 ìg/d of folic acid, for a minimum of 6 weeks, can lower systolic blood pressure slightly; but the real clinical benefit is achieved through improved endothelial function.
This abstract is reproduced with the permission of the publisher; free full text available.