Selenium status can be measured by the quantification of biomarkers in the blood. Previous studies have shown that genetic polymorphisms can affect Se status and modulate risk for chronic diseases. In this study, five biomarkers will be quantified in the blood, before and after supplementation with Brazil nuts. The genetic variants will be used to stratify the biomarkers and multivariate linear regressions will be used to explore the influence of the polymorphisms on concentrations of the biomarkers .