Selenium: occurrence in foods and its toxicological significance--a review.

The occurrence of selenium (Se) in foods and the toxicological information relevant to it are reviewed. The estimated normal dietary daily intake for man in most parts of the world ranges from 4-35 microgram/person in infants to 60-250 microgram/person in adults. The current use of Se supplementation in animal feeds could elevate the Se content of meats by up to 30%, but this does not lead to a biologically relevant increase in the Se intake of man. Available metabolic data reveal that after ingestion Se is mostly absorbed. Up to 50% is excreted in the urine, and the portion retained in the body accumulates chiefly in the liver and kidneys. Recent epidemiological and animal studies show that Se is not a carcinogen, and in some cases may have anti-cancer properties. Neither the essentiality for man, nor the no-effect level of Se have been established. Human selenosis of food origin has not been reported in the literature, except those documented in the 1930s in the seleniferous areas.