Physiological function of Se-enriched tea fertilised with sodium selenite and naturally high-Se tea in rats

In order to increase food selenium (Se) content, Se-enriched tea was produced by fertilising with sodium selenite in low-Se soil. Five groups of rats were fed a low-Se diet supplemented with either water (Se-deficient), sodium selenite or an aqueous extraction of low-Se tea, Se-enriched tea or naturally high-Se tea. The chemical form of Se in Se-enriched tea and the physiological function in rats fed the different Se sources were determined after 8 weeks. The results showed that organic Se accounted for 80% or more of the Se in Se-enriched tea fertilised with sodium selenite and naturally high-Se tea, but no significant differences in the proportion of organic Se and protein Se were found between Se-enriched tea and naturally high-Se tea. The Se biological utilisation rates were 65.41, 68.05 and 70.49% for sodium selenite, Se-enriched tea and naturally high-Se tea respectively. The Se content of blood and liver and the glutathione peroxidase (GSH-Px) activity were significantly increased by feeding Se-enriched tea and sodium selenite compared with low-Se tea, but a more efficient increase in liver GSH-Px activity was obtained with Se-enriched tea than with sodium selenite. No significant differences were found between Se-enriched tea fertilised with sodium selenite and naturally high-Se tea, which proved that the biological effectiveness of Se in Se-enriched tea was higher than that of sodium selenite in increasing liver GSH-Px activity. Se-enriched tea fertilised with sodium selenite in low-Se soil gave the same biological function as naturally high-Se tea. Therefore Se-enriched tea is a safe and effective means of increasing the Se intake of both humans and animals in low-Se areas. (C) 2000 Society of Chemical Industry.