If soy isoflavones bind to estrogen receptors, is this good or bad?
We don’t have enough information to answer this. We do have enough information to say that the answer will not be a simple “yes” or “no.” In some cases, when isoflavones bind to the estrogen receptor, the effect is similar to the effect of estrogen. In other cases, isoflavones bind to the estrogen receptor and block the effects of estrogen. Sometimes isoflavones mimic estrogen Sometimes isoflavones block estrogen binding to its receptor We know, for example, that treatment of female baby rats with estrogen will advance the onset of puberty, that is, puberty will occur earlier in the estrogen-treated rats. If soy isoflavones act like estrogen, we would expect rats fed isoflavones to reach puberty earlier than those that did not receive isoflavones. On the other hand, if soy isoflavones block the effects of estrogen when they bind to the estrogen receptor, we would expect puberty to be delayed in female rats given soy isoflavones. Since estrogen rises at puberty, and puberty also involve
