Effect of fertilization on selenium content of tea and the nutritional function of Se-enriched tea in rats

The present study examined the effect of fertilization with sodium selenite on the selenium content of tea and the nutritional function of Se-enriched tea. Selenium content of tea leaves was increased up to 0.36 mug g(-1) by the application of sodium selenite to soil at 0.5 and 1.0 kg Se ha(-1). Application by a Se-enriched organic manure at a rate of 0.5 kg Se ha(-1) provided a higher biological availability of selenium for plant uptake compared with a similar amount of sodium selenite. Foliar spray of sodium selenite at 50-100 g Se ha(-1) increased the selenium content to 0.32-1.45 mug g(-1) in tea leaves sampled at the 8-26 days after spraying. Selenium content in the blood and liver, glutathione peroxidase activity in blood of rats were significantly enhanced by feeding of an extracted solution of Se-enriched tea leaves and sodium selenite. Glutathione peroxidase activity in liver of rats fed with Se-enriched tea was higher than that fed with sodium selenite, indicating that the selenium in Se-enriched tea leaves is a more effective Se source than sodium selenite. Increasing the Se level in food products through the application of a selenium fertilizer is a safe, effective and feasible means of increasing the selenium intake of human and animals in low selenium areas of China.