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:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369135/
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.
http://www.ncbi.nlm.nih.gov/pubmed/22024780
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.
http://www.ncbi.nlm.nih.gov/pubmed/20924975
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.
- Allen
