Statin therapy and plasma vitamin E concentrations: A systematic review and meta-analysis of randomized placebo-controlled trials

BACKGROUND: Vitamin E is one of the most important natural antioxidants, and its plasma levels are inversely associated with the progression of atherosclerosis. There have been reports suggesting a potential negative effect of statin therapy on plasma vitamin E levels. The aim of this meta-analysis was to determine the impact of statin therapy on plasma vitamin E concentrations. METHODS: PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched to identify randomized placebo-controlled trials evaluating the impact of statins on plasma vitamin E concentrations from inception to February 27, 2015. A systematic assessment of bias in the included studies was performed using the Cochrane criteria. A random-effects model (using DerSimonian-Laird method) and the generic inverse variance method were used to examine the effect of statins on plasma vitamin E concentrations. Heterogeneity was quantitatively assessed using the I(2) index. Sensitivity analysis was conducted using the leave-one-out method. RESULTS: A meta-analysis of data from 8 randomized treatment arms including 504 participants indicated a significant reduction in plasma vitamin E concentrations following statin treatment (WMD: -16.30%, 95% CI: -16.93, -15.98, p < 0.001). However, cholesterol-adjusted vitamin E concentrations (defined as vitamin E:total cholesterol ratio) were found to be improved by statin therapy (WMD: 29.35%, 95% CI: 24.98, 33.72, p < 0.001). Statin therapy was not associated with any significant alteration in LDL vitamin E content (SMD: 0.003, 95% CI: -0.90, 0.90, p = 0.995). CONCLUSION: Findings of the present study suggest that statin therapy has no negative impact on plasma vitamin E concentrations or LDL vitamin E content.