A team of scientists has documented in a series of lab experiments that a little-known molecule, formed when soy is consumed, inhibits the actions of a potent male hormone, altering physiological responses of rats' reproductive organs.
The researchers, in a combined effort involving Brigham Young University, Colorado State University and the Cincinnati Children's Hospital Medical Center, wanted to determine the role of equol, a molecule that is formed in the intestines from one of the isoflavones found in soy foods. In the new issue of the journal "Biology of Reproduction," they report that equol directly binds a key androgen hormone.
Two experiments showed that injections of equol in male rats reduced the size of the prostate gland and epididymis, which normally grow under the influence of the potent male hormone called dihydrotestosterone or DHT.
"The novelty of equol is that it both inhibits androgen hormone and influences estrogen hormone action," said Edwin D. Lephart, a professor in the Department of Physiology and Developmental Biology and director of the Neuroscience Center at Brigham Young University. "We do not know of any other molecule that possesses these important biochemical properties."
The researchers have already initiated further studies of equol to investigate its possible development as a treatment for androgen-mediated conditions. Prior research has established the relevance of DHT in the growth of some male reproductive organs, hair growth (scalp and facial), skin health and emotional state. The team has filed patent applications on equol and is seeking to commercialize the technology.
The researchers also report another piece of evidence that equol renders DHT inactive -- higher levels of equol in the bloodstream lead to increased levels of a pituitary hormone normally suppressed by DHT.
"To date no compound other than equol has been shown to do this to DHT, to directly bind the hormone rather than block its receptor or the enzymes involved in its [DHT] synthesis" said Trent D. Lund, lead author of the study, and assistant professor in the Department of Biomedical Sciences at Colorado State University's College of Veterinary Medicine.
"By directly binding and inactivating DHT without influencing testosterone, gives equol the ability to reduce many of the harmful effects of androgens without affecting the beneficial ones", said Robert J. Handa, a professor and associate head of graduate studies in the Department of Biomedical Sciences at Colorado State University.
"These findings are of immense clinical importance because blocking the action of the potent androgen, DHT, has been one of the 'holy grails' of the pharmaceutical industry in developing strategies for treating prostate cancer and other related diseases – this natural metabolite made from soy isoflavones does this very effectively" ," said Kenneth D.R. Setchell, a professor in the Department of Pediatrics and Director of the Clinical Mass Spectrometry laboratory at Children's Hospital Medical Center
Joining Lund, Lephart, Setchell, and Handa as authors of the study are Daniel J. Munson, Megan E. Haldy.
Writer: Joseph Hadfield