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Selenium Health

Rationale for Using Selenium to Prevent Prostate Cancer

The incidence of prostate cancer has reached near epidemic proportions, making the identification of safe, non-toxic compounds for the chemoprevention of prostate cancer a high research priority.   Selenium, an essential nutrient required for a number of metabolically important enzymes (including the antioxidant glutathione peroxidase), can inhibit cancer development in a variety of experimental animal models.  In 1996, Clark and co-workers (J Am Med Assoc 1996; 276: 1957-1963) reported the results of a 13 year, randomized, placebo-controlled study with older Americans which showed that daily use of an oral selenium supplement substantially reduced the risk of several cancers, most notably cancer of the prostate (63% risk reduction).  These results suggested the exciting possibility that significant reductions in cancer risk may be realized with low, non-toxic doses of selenium that could readily be achieved by dietary supplementation.  In 2001, the National Cancer Institute initiated a 12-year clinical trial (SELECT) that will study more than 32,000 men to evaluate whether daily supplementation with selenium +/- vitamin E decreases the incidence of human prostate cancer.  However, the mechanisms of how selenium exerts its anticancer effects are unknown.

Murphy Foundation Scientists Report New Findings on the Prostate Cancer Fighting Mechanism of Selenium

Optimizing selenium as a prostate cancer prevention strategy will require knowledge of how selenium affects prostate cells.  We hypothesized that selenium supplementation might exert its anticancer effect by reducing naturally-occurring genotoxic damage within the aging prostate.  To test this hypothesis, we studied the effect of 7 months of selenium supplementation on DNA damage in prostate cells of elderly beagle dogs that were physiologically equivalent to 62-69 year old men and free of prostate cancer.  Daily supplementation with non-toxic doses of selenium, given as either selenomethionine or high selenium yeast, was associated with a significant decrease in DNA damage in prostate cells as measured by Comet assay.  These data were published in a recent issue of the Journal of the National Cancer Institute:

Waters DJ, et al. Effects of dietary selenium supplementation on DNA damage and apoptosis in canine prostate. J Natl Cancer Inst 2003; 95:237-241. 

To access the scientific abstract of this work, please visit;95/3/237

Importance of the Murphy Foundation’s Research on Selenium and Prostate Cancer Prevention is Recognized by Science News Online

Selenium is a constituent of the enzyme glutathione peroxidase, one of the body’s more potent antioxidants.  Such agents have the ability to quash biologically damaging reactions triggered within the body by any of a host of naturally produced chemicals called oxidants. Because oxidant damage has been linked with many cancers, some scientists have suspected that any anticancer benefit from selenium is probably due to its antioxidant properties. In fact, several new studies suggest that at least one of the nutrient's primary anticancer benefits may be its protection or repair of a suicide switch in genetically damaged cells. It's when the body allows this switch to fail that cancer's runaway growth occurs. Cancers are typically traced to DNA damage, and Waters' team found far less DNA damage in the white blood cells and the prostate tissue of dogs treated with selenium than in the untreated group. For instance, 79 percent of the prostate cells examined from untreated dogs had “extensive DNA damage” compared with just 57 percent of such cells from dogs getting supplemental selenium. So how does selenium protect the prostate? It may be by controlling the selective culling of cells with damaged DNA. Normally, cells develop, grow old, and then die. Cancer cells, however, don't die naturally. Like Methuselah, they seem immortal and continue to produce endless progeny throughout their long lives. Cancer cells would pose far less of a problem if the normal suicide switch within them could be reactivated.  Such programmed cell death is known as apoptosis.  Interestingly, Waters’ team found roughly twice the level of apoptosis occurring within the prostate tissue of selenium-supplemented dogs as in untreated beagles.  The elevated apoptosis in the selenium-treated animals could put a break on the development of prostate malignancies.

Source:  from Food for Thought : Selenium’s Value to Prostate Health by Janet Raloff. Science News Online, Week of May 3, 2003; Vol. 163, No. 20.

The Murphy Foundation’s Selenium and Prostate Cancer Research is Cited in Urology Times

Selenium, when given as a dietary supplement, decreases DNA damage and increases epithelial cell apoptosis in the prostates of elderly dogs, report researchers from Purdue University and the Gerald P. Murphy Cancer Foundation. While their findings involve animals, the results add to a growing body of scientific evidence that selenium supplementation may be useful in preventing prostate cancer in men. The data may also heighten anticipation of the findings of a large, multinational study examining the potential preventive effect of selenium and vitamin E against prostate cancer.

“This is an important finding. Dogs are the closest animal models to humans when it comes to prostate cancer,” said Ian Thompson, MD, Professor and Chief of Urology, University of Texas Health Science Center, San Antonio. “In this new study, we have another example of selenium altering an intermediate biomarker that may predict its efficacy in reducing the risk of prostate cancer.”

 “When SELECT is done we will know the answer,” Dr. Thompson said.  “While the evidence regarding selenium suggests that it is safe and may have an effect, it will take the SELECT trial to determine the final answers to these questions.”

Source:  from Selenium Lowers Prostatic DNA Damage in Canine Model by John Schieszer. Urology Times, May 2003, Vol. 31, No. 5, p. 4.

Our Current Research on Selenium and Prostate Cancer Prevention

Basic and Comparative Research

  • Elucidating the mechanisms of selenium’s anticancer effects
  • Evaluating the interactions of selenium with other cancer preventive agents

From the Library

For a list of published scientific articles which highlight the importance of the trace mineral selenium in health and disease, click the link above.

What can you do now to help prevent prostate cancer?

The Murphy Foundation remains committed to the importance of men maintaining a healthy level of selenium as a protective measure against prostate cancer. What we now know is that too much may, in fact, be as detrimental to prostate health as too little! Indeed, often the most health conscious among us develop higher levels than are healthy. The SeleniumHealth Test™ is a simple, non-invasive test men can take to monitor their selenium levels. Learn more about the SeleniumHealth Test.

SeleniumHealth Test™ is a trademark of the Gerald P. Murphy Cancer Foundation.