Study participants were selected at random to receive either 200 micrograms of the mineral selenium or a placebo. The authors had hypothesized that administering selenium might reduce the risk of new basal and squamous cell skin carcinomas. They were wrong. The rest of this story, however, was totally unexpected and led to the publication of these findings in the prestigious Journal of the American Medical Association . There were particularly significant reductions in new lung, colorectal, and prostate malignancies.
Selenium is a trace element.
It was discovered in 1818 and is part of the periodic table, where its closest relative is sulfur. Selenium readily forms compounds with sulfur-containing amino acids, including methionine, an amino acid essential to normal metabolism. Virtually all selenium is found in proteins called selenoproteins. Some 35 selenoproteins have been described to date. Glutathionine peroxidase, a powerful antioxidant, is the best known and most studied selenoprotein.