The problem with soy protien is that it has Phyto-estrogens that behave like ESTROGEN in your body, which is cleary the opposite of what anyone trying to build muscle wants. Watch out for the use of soy protien in fitness bars as it is relatively cheap in cost and is more or less used as a replacement protien for pricier, higher quality protiens. Soy IS NOT a health food despite what you hear in the media... it is dangerous to consume unless it has been fermented for at least a year, something that the health officials fail to inform you of and the soy pushers fail to follow through on. Please do your homework. Thanks, -J.