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Meta-Analysis
. 2006 Oct;84(4):762-73.
doi: 10.1093/ajcn/84.4.762.

Selenium and Coronary Heart Disease: A Meta-Analysis

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Free PMC article
Meta-Analysis

Selenium and Coronary Heart Disease: A Meta-Analysis

Gemma Flores-Mateo et al. Am J Clin Nutr. .
Free PMC article

Abstract

Background: It is hypothesized that low selenium concentrations are associated with an increased risk of cardiovascular disease and that selenium supplements prevent coronary heart disease.

Objective: The objective was to perform a meta-analysis on the association of selenium biomarkers with coronary heart disease endpoints in observational studies and on the efficacy of selenium supplements in preventing coronary heart disease endpoints in randomized trials.

Design: The MEDLINE and the Cochrane Library databases were searched for studies conducted from 1966 through 2005. Relative risks were pooled by using an inverse-variance weighted random-effects model.

Results: Twenty-five observational studies (14 cohort and 11 case-control studies) that measured blood or toenail selenium concentrations and 6 randomized trials that evaluated supplements containing selenium met our inclusion criteria. The pooled relative risk in a comparison of the highest with the lowest selenium concentration categories was 0.85 (95% CI: 0.74, 0.99) in cohort studies and 0.43 (0.29, 0.66) in case-control studies. In observational studies, a 50% increase in selenium concentrations was associated with a 24% (7%, 38%) reduction in coronary heart disease risk. In randomized trials, the pooled relative risk in a comparison of supplements containing selenium with placebo was 0.89 (0.68, 1.17).

Conclusions: Selenium concentrations were inversely associated with coronary heart disease risk in observational studies. Because observational studies have provided misleading evidence for other antioxidants, the validity of this association is uncertain. Few randomized trials have addressed the cardiovascular efficacy of selenium supplementation, and their findings are still inconclusive. Evidence from large ongoing trials is needed to establish low selenium concentrations as a cardiovascular disease risk factor. Currently, selenium supplements should not be recommended for cardiovascular disease prevention.

Figures

FIGURE 1
FIGURE 1
Flow diagram of study selection process. CHD, coronary heart disease.
FIGURE 2
FIGURE 2
Meta-analysis of the association of selenium with coronary heart disease in observational studies. Studies are divided by study design (cohort or case-control) and by selenium biomarker (serum, toenail, erythrocyte, or whole blood). Relative risks (RRs) correspond to comparisons of extreme categories of exposure within each study. The area of each square is proportional to the inverse of the variance of the log RR. Horizontal lines represent 95% CIs. Diamonds represent pooled estimates from inverse-variance weighted random-effects models. For case-control studies with multiple biomarkers, we used the biomarker with the longest half-life (toenail > whole blood and erythrocyte > serum) to measure the overall RR. Ca, case subjects; NC, noncase subjects; DM, diabetes mellitus; HT, hypertension; SES, socioeconomic status; Hb, hemoglobin. ▪ Indicates categories that were adjusted for; □indicates categories that were not adjusted for.
FIGURE 3
FIGURE 3
Dose-response meta-analysis of selenium and coronary heart disease in observational studies (shown by first author and year of publication). The pooled linear risk trend (thick solid line) and its 95% CI (dashed lines) were obtained by a random-effects dose-response meta-analysis. Circles are inversely proportional to the variance of log relative risks.
FIGURE 4
FIGURE 4
Meta-analysis of selenium and coronary heart disease in randomized trials. *Baseline selenium concentrations were measured in serum (Korpela et al 1989 and Hercberg et al 2004 studies) and plasma (Stranges et al 2006 study). NM, not measured; NR, not reported; RR, relative risk.

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