New evidence suggests preventive effect of herbal supplement in prostate cancer

Jan 12 2009

DHEA is a natural circulating hormone and the body's production of it decreases with age.

Men take DHEA as an over-the-counter supplement because it has been suggested that DHEA can reverse aging or have anabolic effects since it can be metabolized in the body to androgens. Increased consumption of dietary isoflavones is associated with a decreased risk of prostate cancer. Red clover (Trifolium pretense) is one source of isoflavones. Both supplements may have hormonal effects in the prostate and little is known about the safety of these supplements.

In a recent report in Cancer Prevention Research, a journal of the American Association for Cancer Research, researchers report that DHEA levels can be manipulated in cells in the laboratory to understand its effects.

Julia Arnold, Ph.D., a staff scientist at the National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health, said more research is necessary in an environment where men and women concerned about health problems tend to self-prescribe based on information they find on the Internet.

Towards this end, the NCCAM laboratory is studying signaling between human prostate cancer cells and their supporting stromal cells as they grow together in laboratory culture. "DHEA effects in the prostate tissues may depend on how these two cells types 'talk to each other' and further, it may be potentially harmful in tissues containing inflammation or with early cancer lesions because the cells can induce DHEA to become more androgenic," said Arnold.

Combining DHEA with transforming growth factor beta-1 increased testosterone production in the stromal cells and prostate specific antigen protein secretion two to four-fold and gene expression up to 50-fold in the cancer cells. When these cell cultures were treated with red clover isoflavones, the androgenic effects of DHEA were reversed.

"Something is happening in the prostate tissue microenvironment that is illustrating a potential cancer prevention effect from this supplement," said Arnold.

Red clover isoflavones may modify androgenic effects in the prostate but much more work in the laboratory and clinic is needed to validate these effects.

This sort of laboratory manipulation will allow scientists to understand the basic prostate biology as well as learn cellular and molecular mechanisms of over-the-counter supplements and other botanical or herbal agents. Arnold said NCCAM will continue to study DHEA with other supplements to determine any cancer preventive effects.