Selenium May Fight Prostate Damage

Feb. 4, 2003 -- Boosting the daily dose of selenium may help elderly men keep their prostates healthy and reduce their risk of prostate cancer. A new study shows elderly dogs that ate a diet supplemented with selenium had less age-related DNA damage to their prostates, which may reduce the risk of prostate cancer.

Selenium is an essential nutrient required in small amounts by the human body for a number of vital processes, including some that are thought to reduce the risk of certain types of cancer. The most common dietary sources of selenium are meats, fish, cereal, dairy products, and eggs.

Researchers say that the effect of aging on prostate cancer development is similar in dogs and humans -- the only two species in which prostate cancer occurs spontaneously and with significant frequency. In fact, prostate cancer is the second leading cause of cancer death among men in the U.S.

In the study, researchers selected elderly beagle dogs that were comparable to 62- to 69-year-old men and fed them either a diet that had been supplemented with selenium or a regular diet for seven months and compared the effects of the diets on their prostates.

The results appear in the Feb. 5 issue of the Journal of the National Cancer Institute.

Researcher David J. Waters, DVM, PhD, of the school of veterinary medicine at Purdue University, and colleagues found that dogs fed the supplemented diet had a significantly lower percentage of prostate cells with extensive DNA damage than the others. About 80% of the prostate cells in dogs fed a normal diet had extensive DNA damage compared with only about 57% in the selenium-treated dogs.

In addition, dogs fed the enriched diet also had a twofold increase in the number of prostate cells that had undergone a process that removes damaged cells, called apoptosis, which is associated with a lower risk of cancer.

Researchers say the results show that selenium may help protect cells within the aging prostate from initial DNA damage before the cells develop major problems that might lead to cancer, but more research is needed to see if the same effect holds true in humans.