DIETARY PROTEIN AND THE TOXICITY OF SODIUM SELENITE IN THE WHITE RAT

¹ From the Department of Biological Chemistry, Medical School, University of Michigan, Ann Arbor

1. Diets containing 30 per cent of casein afforded significantly more protection to young white rats against selenium intoxication (sodium selenite at levels of 25 to 50 p.p.m. selenium) than did diets of equal caloric value containing 6 per cent of casein. This protection was manifested by longer periods of survival and less marked effects on growth.

2. Methionine (0.45 to 0.89 per cent) added as a supplement to the 6 per cent casein diet containing selenium also afforded similar protection. Cystine added to the diets in amount equivalent to methionine did not significantly increase the period of survival or improve growth in the presence of selenium.

3. Supplementary methionine, added to a selenium-containing diet, whose protein was supplied by arachin, a protein notably low in its methionine content, at a 15 per cent level, afforded protection against the toxic effects of selenium.

4. These experiments suggest that the character of the dietary protein and protein supplements may materially modify the toxicity of inorganic selenium compounds.