INFLUENCE OF SELENIUM ON THE ABSORPTION, EXCRETION AND PLASMA LEVEL OF TRITIUM-LABELLED VITAMIN E IN THE RAT

Abstract

In two experiments the influence of selenium supplementation of a basal diet low in both selenium and vitamin E on the absorption, excretion, and blood distribution of a single dose of tritium-labelled α-tocopherol in rats was examined. Urinary and fecal excretion of radioactivity was determined at 24-hour intervals over a three-day period. In experiment 1, supplementation with 0.5, 1.0 or 2.0 ppm selenium had no significant effect on the absorption or urinary excretion of the radioactivity. In the second experiment, supplementation with 2.0 ppm selenium again had no significant effect on absorption or excretion of the labelled tocopherol. A group receiving dietary supplementation of 500 IU vitamin E per kg diet excreted significantly more of the dose in the urine (P < 0.01) and in the feces (P < 0.05) than did the basal group. The plasma level of radioactivity was significantly lower (P < 0.01) in the selenium-supplemented group than in the basal animals. Chemical determination of the plasma α-tocopherol level similarly indicated lower values in the selenium-supplemented animals. These results suggested a possible role for selenium in promoting the withdrawal of vitamin E from the blood by the tissues. Levels of radioactivity were higher in the heart and liver tissue of the selenium-supplemented animals, but the differences were not statistically significant (P > 0.05). In the rat, selenium does not appear to influence the absorption or retention of vitamin E, but does affect the plasma vitamin E level and may modify its distribution in the tissues.