Selenium and its association with oxidative stress and genotoxicity risk in a healthy Italian population: a cross sectional study

Background Selenium is present in trace amounts and different chemical forms in living organisms, which may beneficially and adversely affect cellular redox status. 8-oxo-7,8-dihydro-2’deoxyguanosine (8-oxodG) is an oxidized derivative of deoxyguanosine and a sensitive biomarker of oxidative stress and genotoxicity in biological systems. In this study, we aimed to determine if selenium exposure in a population in Northern Italy may be associated with 8-oxodG levels in urine and if sex and other factors may influence such association. Methods/Approach We recruited 137 substantially healthy and non-smoking blood donors from the Reggio Emilia province at the Transfusion Medicine Unit of the Reggio Emilia Hospital. Their median age was 48.2 years, and the recruitment occurred 2017-19. We assessed selenium in urine and serum, and urinary 8-oxodG levels. We also speciated selenium in serum. We used cubic spline regression analyses to investigate the association between selenium matrices and urinary content of 8-oxodG/g creatinine. Results Median urinary selenium and 8-oxodG levels were 22.02 µg/L and 3.21 µg/g creatinine, respectively. Median total serum concentrations were 116.50 µg/L in the 104 individuals for which a serum sample was available. We found that urinary selenium positively correlated with 8-oxodG levels in men, while in women an inverted U-shaped association emerged. Total organic selenium and selenoprotein P levels were positively associated with 8-oxodG until 100 µg/L and then the association became slightly inverse in both sexes. In males, glutathione peroxidase-bound selenium, selenomethionine and human serum albumin-bound selenium were positively correlated with 8-oxodG, while negative associations emerged for inorganic selenium species. In females, positive associations, though slightly positive, emerged for organic species. Conclusions Our study highlights the different role played by selenium compounds, suggesting that organic selenium - but not its inorganic species - may exert genotoxic effects, and that sex considerably influences the risk of oxidative stress and genotoxicity associated with selenium exposure.