Selenium Shown to Protect Men Against Prostate Cancer

Aside from skin cancer, prostate cancer is the most common type of cancer in American men, according to the National Cancer Institute. In 2005, there were about 232,090 new cases of prostate cancer and 30,350 deaths in the United States. Though few studies have offered much insight into what causes prostate cancer, a number of researchers have found evidence suggesting that dietary selenium protects men against this disease.

A trace mineral, selenium is found in seafood, meat (especially organ meats such as kidney and liver), plant foods like rice and wheat, and Brazil nuts. It is an antioxidant that has been shown in scientific studies to enhance many aspects of immune function, help protect against a number of chronic disease and control cell damage that can lead to cancer.

One of the first studies making the link between selenium and prostate cancer prevention was the Nutritional Prevention of Cancer Trial, published in 1996 in the Journal of the American Medical Association. The study included 1,312 men and women who had skin cancer. Men who took selenium to prevent nonmelanoma skin cancer received no benefit from selenium in preventing skin cancer; however, men who had taken selenium for six-and-a-half years had approximately 60 percent fewer new cases of prostate cancer than men who took a placebo. This discovery is one of the reasons selenium is being studied in the ongoing Selenium and Vitamin E Cancer Prevention Trial, commonly referred to as SELECT.

Another study published in 2003 in the International Journal of Cancer found that among 445 American men, high blood concentrations of selenium appeared to reduce by 30 percent the risk that a man would develop prostate cancer.

As a powerful antioxidant, selenium has the ability to suppress biologically damaging reactions triggered within the body by naturally produced chemicals called oxidants. Because oxidant damage has been linked with many cancers, scientists suspect that any anticancer benefit from selenium could be traced to its antioxidant characteristics and its ability to protect cells from DNA damage or repair cells already damaged.