Dietary selenium repletion may reduce cancer incidence in people at high risk who live in areas with low soil selenium.

Studies examining the relationship between dietary selenium intake and risk of various cancers have shown that low selenium intake is associated with higher cancer rates. A recent well-controlled intervention trial studied whether selenium supplementation can prevent cancer in subjects who have a history of skin cancer and live in areas of the United States with low soil selenium levels. Selenium supplementation did not reduce skin cancer rates, but the incidence of total, lung, colorectal, and prostate cancers was significantly reduced by the intervention. Although these data need confirmation, they suggest that adequate selenium intake is essential for cancer prevention.