Objective: To assess changes in selenoprotein P levels in plasma from subjects who had received oral supplements of different selenium forms. Design: The same study group participated in two similar selenium supplementation trials, Trial I in 1981 () and Trial II in 1987 (). During Trial II the mean baseline intake of selenium in Finland was higher compared to that during Trial I (100 and 40  g/d, respectively), due to a nation-wide supplementation of fertilisers which started in 1985. Subjects: Fifty healthy Finnish men, 36-60 y old. Intervention: The study group received daily placebo or oral supplements consisting of 200 g selenium as selenium-enriched yeast, sodium selenate or selenium-enriched wheat (Trial I) or selenium-enriched yeast, sodium selenate or sodium selenite (Trial II). The duration of supplementation periods was 11 (Trial I) and 16 (Trial II) weeks. Results: In Trial I the mean plasma selenoprotein P values in all the supplemented groups increased significantly, approaching a plateau at 2 weeks and reaching maxima at 4 weeks (mean increase 34%, P<0.05). In Trial II the mean selenoprotein P levels of the supplemented groups were not significantly different from each other or from the placebo group at the start or at any time point of the supplementation period. Conclusions: At a low selenium status the selenoprotein P levels increased in a similar fashion after supplementation with different forms of selenium, but at a high selenium status no significant effects of supplementation with the same amount of selenium were observed. No differences in selenoprotein P levels were observed for inorganic and organic selenium supplements. Sponsorship: This study was supported by The Swedish Council for Forestry and Agricultural Research, the Påhlsson Foundation and the Swedish Nutrition Foundation. | 
