According to an article recently published in the American Journal of Clinical Nutrition, soy isoflavones appear not to damage DNA of cancer patients or healthy volunteers.
The prostate is a male sex gland that is located between the bladder and the rectum and is responsible for creating a component of semen. Several treatment options exist for patients with prostate cancer, including watchful waiting, surgical removal of the prostate (radical prostatectomy), radiation therapy, cryosurgery, and/or hormone therapy. Researchers are also investigating complementary and alternative medicine (CAM) therapies. CAM consists of various therapies, such as acupuncture, massage therapy, and vitamin supplementation. Clinical research into the efficacy of specific CAM therapies on treating cancer, managing symptoms, and/or promoting wellness provides evidence for cancer patients and their physicians seeking to make informed decisions.
Soy is sometimes utilized as a type of CAM and categorized as a biologic/orthomolecular therapy. Soy comes from soybeans, a plant indigenous to east Asia. Laboratory research has isolated components of soy, known as isoflavones, that are believed to be its active ingredients. Isoflavone is the general name for a class of compounds that include genistein, daidzein and glycitein. These substances appear to act as phytoestrogens (plant estrogens), exerting weak estrogen effects in the body. Several studies have suggested that isoflavones may help prevent cancer, although clinical trials are needed to confirm these findings. In addition, soy has been promoted as a potential therapy for breast and prostate cancer patients. However, in vitro research has indicated that soy may cause DNA damage to human cells.
In the current study, 20 prostate cancer patients received daily doses of 300 mg genistein for 28 days. Over the following 56 days, each patient consumed 600 mg of genistein each day. At the start of the study, researchers conducted laboratory tests on peripheral lymphocyctes (a type of white blood cell) to determine baseline DNA damage in each patient. Throughout the study, these tests were repeated to monitor changes in frequency of broken DNA strands and rearrangement of genes on DNA. Six healthy volunteers also underwent testing. Concurrently, an in vitro study was conducted to determine the effects of this specific genistein on cultured human cells.
The study reported no changes in the group average or individual levels of DNA damage. Surprisingly, one test of DNA damage exhibited a significant decrease within the first 28 days of the trial. As suggested by previous research, however, genistein did produce genetic damage in cultured human cells.
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These researchers concluded that while in vitro research suggests that genistein can impair DNA, it appears not to induce such damage in human subjects. Additional research is needed more fully explore how genistein works in the body and its potential benefits and drawbacks.
These researchers concluded that while in vitro research suggests that genistein can impair DNA, it appears not to induce such damage in human subjects. Additional research is needed more fully explore how genistein works in the body and its potential benefits and drawbacks. Patients with prostate cancer may wish to speak with their physician about the risks and benefits of CAM or about participation in a clinical trial further evaluating CAM therapies such as genistein. Three sources of information regarding ongoing clinical trials include the National Cancer Institute’s Office of Cancer Complementary and Alternative Medicine at , the National Center for Complementary and Alternative Medicine at , and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients.
Reference: Miltyk W, Craciunescu CN, Fischer L, et al. Lack of significant genotoxicity of purified soy isoflavones (genistein, daidzein, and glycitein) in 20 patients with prostate cancer.
American Journal of Clinical Nutrition. 2003;77:875-82.
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