Nutritional availability of selenium contained in rice

Abstract

The nutritional availability of selenium (Se) contained in rice was estimated by measuring the tissue Se levels and glutathione peroxidase (GSH-Px) activities of rats fed a diet consisting of 90% brown rice. Male weanling rats were fed a casein-based diet (diet A) or, the casein-based diet supplemented with 0.05 or 0.10μg Se/g of selenite (diets B and C, respectively), a low-Se rice-based diet (diet D), or a high-Se rice-based diet (diet E) for 4 weeks. Dietary Se levels measured by fluorometrical analysis were as follows (ng Se/g): A, 18; B, 65; C, 118; D, 24; E, 62. The selenite added to the casein-based diets dose-dependently increased the Se levels and GSH-Px activities in the blood and liver of the rats. The tissue Se levels and GSH-Px activities in the rats fed the rice-based diets (diet D or E) were comparable to those in the rats fed diet A or diet B, respectively. The nutritional availability of rice-selenium, estimated by using the general equation: GSH-Px activity or tissue selenium level=m×log (dietary selenium level)+k, was 65-107% compared to selenite.