Selenium bioavailability of soy-based diets in rats

Abstract

Bioavailability of selenium from soy grown with sodium selenite and sodium selenate was evaluated by the use of glutathione peroxidase activity regeneration in rats. Male weanling Sprague-Dawley rats were fed a selenium-deficient Torula yeast-based diet for 4 weeks followed by a 7-week repletion period during which animals were fed one of six experimental selenium repletion diets. Soybeans grown with selenite and selenate were processed into flour and used as the protein source in diets providing 50 and 100 ng/g selenium. Bioavailability was determined by liver and plasma glutathione peroxidase regeneration and tissue selenium repletion in response to Se in soy diets and compared with changes in response to Se in reference diets containing Torula yeast supplemented with sodium selenite. Results indicate that selenium from soy was as bioavailable as sodium selenite from the reference diet. In addition, selenium from soy grown with sodium selenite was as bioavailable to the rat as selenium from soy grown with sodium selenate. These data indicate that soy protein provided a bioavailable source of dietary selenium to rats and that the form of selenium available in plants did not influence selenium bioavailability of the resulting soy-based product.