Soy protein with isoflavones reduces levels of estradiol in men with a high risk of developing prostate cancer and may protect them from developing advanced disease

58 men at high risk for developing advanced prostate cancer were supplemented with one of 3 different protein supplements. All 3 supplements supplied 40 grams of protein; one protein was from soy and it supplied 107mg of soy isoflavones, the second was similar but with a low isoflavone content (and the third was from milk protein isolate which served as a placebo. Both soy protein groups excreted much greater amounts of estradiol at 3 and 6 months into the study. At 6 months the high potency isoflavone group also had a switch to a more protective estrogen ratio. The study shows that Soy Protein isolate especially if high in soy isoflavones can help protect men prone to prostate cancer. The study was performed at the University of Minnesota and is published in the October 2007 issue of the Journal of Nutrition.