Selenium in serum, toenails and diet in an italian population

Background. Selenium is a trace element of strong toxicological and nutritional interest, and its deficiency and excess have been involved in the etiology of several human diseases. Uncertainties exist about current selenium status in the Italian population and the optimal methodologies to be used to assess intake of this metalloid in epidemiologic studies.Applied techniques. We analyzed in 56 randomly selected residents in Modena, a municipality of northern Italy, the selenium concentrations in serum and in toenails and the dietary intake of the metalloid. We also investigated the correlations between these indicators of selenium exposure. Serum and toenail selenium levels were determined using atomic absorption spectrometry with Zeeman background correction and neutron activation analysis, respectively, and dietary intake was assessed using a semiquantitative food frequency questionnaire and a specifically developed database of selenium content in foods. Correlation analysis was carried out by calculating Spearman correlation coefficient.Important results. Mean serum selenium concentration was 85.9 µg/l, with a median value of 89.2 and a standard deviation of 21.7. Average levels were higher in females (89.7) than in males (81.2). Mean toenail selenium was 0.65 µg/g, with higher values in females (0.68) than in males (0.61). Dietary selenium intake averaged 59.4 µg/day (standard deviation 19.7), with slightly higher figures for males (60.1) than for females (58.8). We found an association of serum selenium concentrations with toenail levels of the metalloid (P=0.045) but not with dietary intake (P=0.285). Despite the limitations of the study due to the small sample size, these observations clearly indicate the complexity of assessing selenium status, suggesting an association between biological indicators of exposure such as serum and toenail selenium content, and little relation between dietary intake and biomarkers.