Selenium and colorectal adenomas risk: a meta-analysis.

Selenium, as an important component of some antioxidants, has been suggested to have protective effects against colorectal adenomas. This meta-analysis examined the association between selenium level in blood and risk of colorectal adenomas. Data from 7 studies (3 cross-sectional studies, 3 case-control studies, 1 nested case-control study) published before December 2011 was included in this meta-analysis. Fixed and random-effects model was explored to calculate odds ratio (OR) and 95% confidence intervals (CI). Heterogeneity among studies was measured using Cochrane Q-test together with the I (2) statistic. There was a significant inverse correlation between selenium level and colorectal adenomas risk according to fixed-effects model. The overall OR of highest selenium level to lowest for colorectal adenomas is 0.67 (95% CI: 0.55-0.81). Heterogeneity was moderate among the pooled studies (P = 0.05 for the Q test, I (2) = 48%). These results suggested a protective effect of selenium for colorectal adenomas. Some factors, such as age, gender, smoking, and characteristics of the adenomas need to be further considered within the association between selenium levels and risk of colorectal adenomas.