The effect of selenium supplementation on coronary heart disease: A systematic review and meta-analysis of randomized controlled trials

Background: Selenium is a crucial mineral with antioxidant and immune functions, and selenium deficiency may increase the risk of coronary heart disease (CHD). However, the effect of selenium supplementation on CHD is still controversial according to numerous randomized controlled trials (RCTs). The aim of our meta-analysis study was to investigate the impact of selenium on CHD. Methods: PUBMED, EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials databases were systematically searched to identify RCTs evaluating the effect of selenium supplementation on CHD mortality, blood lipid profile (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol), serum C-reactive protein (CRP), and the level of glutathione peroxidase (GSH-PX) from inception until September 20, 2016. Odds ratio of CHD mortality and the associated 95% confidence intervals (CIs) were calculated using the fixed effect model. Weighted mean difference or standardized mean difference (SMD) and 95% confidence intervals (CIs) were calculated to determine the lipid profile, serum CRP, and GSH-PX using fixed effect or random effect models depending on the observed heterogeneity. Results: A total of 16 eligible RCTs with 43998 participants were included. Significant effects were observed for serum CRP (SMD = -0.48; 95% CI, -0.96 to 0; p = 0.049) and GSH-PX (SMD = 0.5; 95% CI, 0.36-0.64; p < 0.001) after selenium supplementation. However, selenium supplementation was not statistically associated with CHD mortality and an aberrant lipid profile. Conclusion: Selenium supplementation decreased serum CRP and increased the GSH-PX level, suggesting a positive effect on reducing oxidative stress and inflammation in CHD. However, selenium supplementation is not sufficient to reduce mortality and to improve the lipid status.