The University of Arizona-Cornell research team reported in 1991 that low selenium levels in the blood were linked to increased risk of neoplastic polyps in the colon, a precursor to colorectal cancer. And in other studies at Cornell, colleagues of Combs' reported in 1995 that animals fed diets high in selenium had 50 percent fewer tumors than those fed diets of average selenium content.
Combs is not recommending the use of oral supplements of selenium; however, he does emphasize the importance of consuming low-fat diets that are adequate in selenium and are balanced with respect to other essential nutrients. The most important dietary sources of selenium are meats, fish and cereals; dairy products and eggs contribute significant amounts. Some nuts can also be high in selenium if they were grown in high-selenium areas.
Of the 40 nutrients currently recognized as essential for human nutrition, selenium was the last to be recognized in 1957. A key component for at least two essential enzymes, selenium provides the body with antioxidant protection in concert with vitamin E and is required for normal thyroid hormone metabolism.
The study was funded in part by grants from the American Institute of Cancer Research, the American Cancer Society and the National Institutes of Health.