Does dietary intake of selenium protect against cancer? A systematic review and meta-analysis of population-based prospective studies

Abstract

Current evidence on selenium and its effects on cancer is conflicting. This study aimed at assessing the association between dietary intake of selenium and incidence of cancers by performing systematic review and meta-analysis of population-based prospective studies. We systematically searched for articles in Medline (Ovid), Embase, Web of Science (Thomson Reuters), China National Knowledge Infrastructure, Wanfang Database and VIP Chinese Scientific Journals. Analysis was performed in Stata version 14.2. Of the 2,564 articles obtained from the databases, 39 met our inclusion criteria, 37 were included in the final analysis. Selenium at recommended daily allowance levels of ≥55 μg/day decreased the risk of cancer [relative risk (RR) = 0.94, 95% confidence interval (CI): 0.90–0.98]. A protective effect was found in men at levels ≥55 μg/day (RR = 0.97, 95% CI: 0.94–0.99). Extra selenium intake from supplements was protective at levels ≥55 μg/day (RR = 0.89, 95% CI: 0.82–0.97). There was an inverse relationship (p value = 0.020) between selenium intake and overall cancer risk after adjusting for age, body mass index, and smoking but there was no evidence of nonlinear relationship (p value = 0.261). The findings in this study suggest that selenium is protective against cancer however the effects vary with different cancers.

Keywords:

• Nutrition
• selenium
• diet
• cancer
• incidence
• systematic review
• meta-analysis
• population
• prospective study

Acknowledgments

We thank GunBrit Knutssön and Carl Gornitzki from the Rearch Consultation Group of the University Library, Karolinska Institutet, Sweden, and Hedong Han from the Department of Health Statistics, the Second Military Medical University, China who helped with the literature search in the various databases.

Conflicts of interest

The authors declare no conflict of interest.

Author contributions

Y.C. and J.A. designed the research; Y.C. and A.K. provided study oversight and took primary responsibility for the final content of the manuscript; A.K., X.F. and M.L. undertook literature screening, data extraction and study quality assessment; X.F. and A.K. performed statistical analysis; A.K. drafted the manuscript; and all the authors contributed to the manuscript writing, made critical revision, read and approved the final manuscript.