The isoflavone genistein in soy was found to inhibit potassium in Guinea pigs, leading to heart arrhythmias (J Biomed Sci 2002; 9:321 - 326). (westonaprice.org)
Suppose the FDA told you that the 2010 NTP Brief on soy formula reports that there is «Clear evidence of adverse effects of genistein in studies with gestational, lactational and post-weaning treatment,» and that «Daidzein has estrogenic activity of its own.» (westonaprice.org)
By comparison, the average level of the soy isoflavone genistein in the bloodstream of Asian women is approximately 25 nanograms per milliliter, but in U.S. women, only 2 nanograms. (whfoods.org)