I'm dismayed in general by the lack of good research on dietary interventions, except Vitamin E and Selenium, which proved supplementation of Selenium to be ineffective and Vitamin E possibly harmful. Epidemiological studies, cohort studies and lab studies are only good for generating hypotheses, imho.Thanks for the reference, but I didn't see anything in there about a stimulatory effect of low doses. I have seen some early data indicating that one should not use genistein alone rather than the naturally occurring mixed isoflavones, however a more recent larger scale study that looked at plasma genistein alone did not show any increased risk:
In one intriguing little uncontrolled study of ten men who had PSA progression after failed RP and salvage RT, some of whom were castrate resistant, half of them had a PSA response lasting an average of 2 years while consuming commercially available soy milk and other soy products.
This seems to back up evidence from lab studies that indicate that soy isoflavones may have several positive benefits for men with prostate cancer. They seems to act by:
- downgrading the androgen receptor (which gets upgraded in response to ADT)
- selectively stimulating the estrogen receptor beta (which suppress PC)
- inhibiting angiogenesis (blood supply for the tumor)
- inhibiting tyrosine kinase (a cancer growth factor)
My friend who's on ADT discussed it with his urologic oncologist who was all for it.
In addition, there has been a controlled pilot study that demonstrated reduced sexual, urinary and rectal side effects after radiation therapy among men who took 200 mg/day.
While it is radioprotective of healthy tissues, it may radiosensitize the cancer cells -- a pretty ideal supplement. Having taken it myself for 6 months afterwards, I would definitely recommend it to anyone having RT. I can't prove it helped me, but it obviously didn't hurt.