SELENIUM METABOLISM AND PLATELET GLUTATHIONE-PEROXIDASE ACTIVITY IN HEALTHY FINNISH MEN - EFFECTS OF SELENIUM YEAST, SELENITE, AND SELENATE

The mean dietary selenium intake in Finland increases from 40 to 100 mu-g/d in 1987 because of the addition in 1985 of selenium to fertilizers. A selenium-supplementation study was performed in 1987 on the same men as were followed in a 1981 study that had a similar design (200 mu-g Se/d). Selenite and selenate, but not selenium yeast increased platelet gluthathione peroxidase (GSHPx) activity by 30% compared with placebo, much less than the 70% found in the previous study. Selenium yeast and selenite increased plasma selenium after 11 wk from 1.39 mu-mol/L to peak values of 2.15 and 1.58 mu-mol/L, respectively. Only yeast selenium was incorporated into red cells. From a regression plot based on present and literature data, it was estimated that the plasma selenium concentration needed to achieve maximal platelet GSHPx activity was 1.25-1.45 mu-mol/L. At the present selenium intake in Finland, 100 mu-g/d, GSHPx activity is saturated in plasma and red cells and almost saturated in platelets.