The soybean contains large quantities of natural toxins or “antinutrients.”
http://www.mercola.com/article/soy/avoid_soy.htm
http://drelaine.com/why-men-should-avoid-soy/
http://www.tandfonline.com/doi/abs/10.1080/07315724.2013.770648#.VCJAD5SSxd8