BRISBANE, AUSTRALIA. There is considerable evidence that selenium may be protective against prostate cancer and there are currently several large clinical trials underway to determine definitively if selenium supplementation decreases the incidence of prostate cancer. Selenium is an important constituent of the body's naturally produced antioxidant, glutathione peroxidase, and its cancer preventive effect may be associated with increased glutathione levels.
If selenium proves to be cancer preventive it is clearly important to know whether selenium levels as measured in a blood sample correlates with actual selenium levels in prostate tissue. Researchers at the University of Queensland recently set out to answer this question. Their clinical trial involved 51 men who had been scheduled for transurethral resection for prostate enlargement. The men were randomly assigned to serve as controls or to receive selenium yeast tablets daily for one month prior to surgery. The tablets provided a total of 200 micrograms/day of selenium. Blood samples were taken at the beginning of the 30- day trial and on the day of surgery and the selenium content of red blood cells was compared to the selenium content of prostate tissue removed during surgery.
The researchers found that the red blood cell level of selenium had increased from 173 ng/mL to 209 ng/mL
in the supplemented group with no significant change among controls. The selenium level in prostate tissue
from supplemented men was significantly higher than among controls (241 ng/g versus 196 ng/g). The
researchers conclude that selenium supplementation is effective in raising selenium levels in both prostate
tissue and red blood cells, but conclude that selenium values from blood testing do not correlate with values
obtained from testing of prostate tissue.