Soy protein and isoflavones: estrogenic or NOT?

There still appears to be controversy over whether soy protein with its isoflavone content(genistein and daidzein) are estrogenic or not in vivo. At a lecture for “Super Nutrients” that I attended it was said that the phytoestrogens from soy have an affinity for estrogen receptors, and that by binding to these receptors, they can block some of the human estrogen circulating in the body from getting into cells. As soy isoflavones are phytoestrogens with an estrogenic activity which is typically only 1/1000th or less than that of human estrogen, this blocking would therefore lower the total estrogenic effect on the body. That was their statement. Surely this kind of assumes that all the estrogen receptors will be occupied, whereas in reality perhaps the isoflavone will have an additive effect on estrogen by binding to free receptors? I am still confused; guys such as Cy and TC are strongly adamant to keep soy out of our diets, whereas well respected experts like Mauro DiPasquale is a strong proponent of the usage of soy protein as part of a blend to reap full benefits. Please do chime in with your own experiences; does soy make you feel shit?

I have used soy for many years and feel just fine on it. Soy protein isolate is my main source of protein.

Soy protein is very good source of protein for body builders. It has a PDCAAS of 1 ranking it with Egg and Whey. It has more glutamine and Arginine than any other protein and almost as much BCAA’s as Whey.
It is best to use combinations of proteins, like whey isolate with milk protein isolate and Soy isolate. Any indication of Soy being somewhat estrogenic is false and any scientific literature indicating such is most likely attributed to raw crude soy preperations, not soy isolate. If soy was estrogenic guys like Bill Pearl or Jeff Everson would not have made the gains they did. These top level body building legends used soy for many years and Jeff Everson has supported soy in many featured article in his planet muscle magazine.

Using steroid using bodybuilders to “prove” that soy is fine is ridiculous. If anyone can read the two articles at T-mag on the dangers of soy and not be concerned then they are fooling themselves. It’s a case where they’d rather be “right” than accept reality. Accepting the obvious truth (soy isn’t good for men) means they have to admit they’re wrong and some peoples’ egos just can’t handle that.

Tek, of course the articles on soy at t-mag make me concerned. However, not everything that t-mag states is 100% correct. I am a vegan and have not had any problems getting bigger and stronger. I have used whey and milk proteins in the past and I did not feel that they were any better than Soy. I think a lot of the anti-soy rhetoric is political nonsense and ploys from the dairy and meat industries. Your view that soy must be bad beacuse t-mag said so is weak.

Read an interesting article on soy last night. Here is the url if you are interested: It goes a little beyond the whole estrogen deal and offers a critical look at soy from a negative point of view. Quite contrary to what I’ve read from earlier health reports. Just thought you’d find it interesting.