Determination of nutritional efficiency of selenium contained in processed skipjack meat by comparison with selenite.

The nutritional efficiency of selenium (Se) contained in two kinds of processed fish meat was appraised. Rats were fed on a 20% casein diet deficient in Se (0.046 micrograms/g diet) for 2 weeks, and were then fed on the basal diet supplemented with 0.08 micrograms/g of Se as sodium selenite, boiled meat of skipjack or dried strip of skipjack for an additional 8 days. The Se-supplementation caused a significant increase of the Se concentration and the glutathione peroxidase activity in the rat liver. Although significant differences in hepatic Se levels were not observed among the rats fed on the Se-supplemented diets, the elevation of the hepatic enzyme activities of the rats fed on the skipjack-supplemented diets was only 45 to 53% that of the rats fed on the selenite-supplemented diet. Amounts of excretion of both fecal and urinary Se of the rats fed on the diets supplemented with the skipjacks were higher than those of the selenite-administered rats. These results indicate that the nutritional efficiency of the Se in the skipjack meat is about 50% that of selenite and that unknown factor(s) other than luminal absorption contribute to the low availability of the Se in the skipjack meat.