The study, published in December 1996, caught the attention of many cancer researchers interested in the role diet and nutrition might play in preventing cancer. Suddenly, Clark says, he had company in his selenium research. Since then scientists have been looking for possible explanations for selenium's apparent good effects. Clark cites a recent report describing a specific type of protein within the prostate that is very responsive to selenium intake. This probably helps protect against oxidative damage there in the prostate.
Selenium is a trace element found to a varying extent in soil.
It enters the human diet through plants such as corn and through the meat of animals grazing on vegetation containing selenium. Products from selenium-rich soils of the Plains and Mountain States carry proportionately more selenium than those coming from the Upper Midwest, Northeast, and Florida, where selenium soil concentration is low. It is often included in broad-spectrum nutritional supplements. There is no official government nutritional guideline on selenium. Typical recommendations range from 70 to 200 micrograms a day.