Chronic toxicity and retention of dietary selenium fed to rats as D- or L-selenomethionine, selenite, or selenate

Abstract

Groups of 8 male weanling Sprague-Dawley rats were fed for 6 weeks Torula yeast-based purified diets containing 2.5, 5.0, or 10.0 μg Se/g added as D-selenomethionine (D-SeMet), L-selenomethionine (L-SeMet), sodium selenite, or sodium selenate. All rats consuming diets containing 10.0 μg Se/g experienced severe growth depression and diet within 29 days, regardless of the form of Se fed, whereas rats fed 2.5 μg Se/g diet gave no evidence of depressed growth and survived the entire experimental period. Selenium fed as D-SeMet was retained in the tissues as strongly as L-SeMet. Skeletal muscle and heart Se concentrations were markedly greater when D- or L-SeMet were consumed than when selenite or selenate were consumed. Lesser differences due to the form of dietary Se fed were seen in the retention of Se in red blood cells, plasma, or liver. The increased deposition of Se in muscle tissues was not reflected by proportionate increases in either plasma or RBC Se, so monitoring plasma or whole blood Se may not indicate the degree of increased total Se body burden.