What is a natural food source? Isn't it anything that actually grows in nature? That phrase doesn't seem to hold valid meaning when applied to a plant that is a source of food and comes from nature. The way they process soy has issues, but the phytoestrogens aren't the issue themselves, they are beneficial to take the place of excess estrogens that do mess with the body. Estrogen is a hormone, and too much or little of it has effects on our physiology.