Effect of vitamin E supplementation on blood pressure: a systematic review and meta-analysis

Although emerging evidence suggests that vitamin E may contribute to blood pressure improvement, the effects of vitamin E on systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) are still controversial. The aim was to evaluate the influence of vitamin E on SBP, DBP, and MAP through meta-analysis. We identified all studies that assessed the effect of vitamin E supplementation on SBP, DBP, and MAP from PubMed/Medline, SCOPUS, and Google scholar up to March 2018. Weighted mean differences (WMD) and 95% confidence interval (CI) were expressed as effect size. Pre-specified subgroup analysis was conducted to evaluate potential sources of heterogeneity. Meta-regression analyses were performed to investigate association between blood pressure-lowering effects of vitamin E and duration of follow-up and dose of treatment. Eighteen trials, comprising 839 participants met the eligibility criteria. Results of this study showed that compared to placebo, SBP decreased significantly in vitamin E group (WMD = -3.4 mmHg, 95% CI = -6.7 to -0.11, P < 0.001), with a high heterogeneity across the studies (I-2 = 94.0%, P < 0.001). Overall, there were no significant effects on DBP and MAP. This meta-analysis suggested that vitamin E supplements decreased only SBP and had no favorable effect on DBP and MAP.