Many respected members of Bodybuilding.net Forums are professional (or at least serious) bodybuilders who make a living from the sport. Recently, I found an article on a 'supplementation' website detailing a little known fact about soy. The article was written by a Certified Clinical Nutritionist with a Doctorate of Philosophy in Nutritional Sciences who goes by the name of Dr. Kaayla T. Daniel.
Soy products have a chemical called phytoestrogensis in them which is known to lower testosterone levels. Studies have been conducted in rats, monkeys and men and prove the theory is correct to some extent.
For men, a reduction in testosterone leads to decreased libido, lower sperm count, and decreases the ability to build muscle. If a bodybuilder is drinking soy milk for its other nutritional values, he or she may be unaware that it is possibly lowering their testosterone level - hence lowering their ability to gain lean muscle.
Other studies show that women who are eating and drinking large quantities of soy complain of fatigue, depression, hair loss, poor skin, and decrease sex drive. This may in fact be ridiculous nonsense; however the research is there to prove relative truth. It is also said that women using soy are at a higher risk of problems with their reproductive system, heavier menstrual flow, increased cramping, and infertility.
With all this being said, many professionals highly recommend you keep your soy intake to around 36 grams per day (should you wish to consume it at all).
There are, however, soy alternatives. Should you not suffer from high degrees of lactose intolerance, 'whey' is a perfect alternate source of protein. If you do suffer from lactose intolerance, it's highly recommended you avoid the whey products as they have the ability to cause major problems with the GL tract.
This thread has no intentions of discriminating the large percentage of users who regularly consume soy milk. This is just an alternate perspective you may want to consider when consuming soy products.
What do you think? Is this enough to put you off?