- Soy contains phytoestrogens, which are known to disrupt endocrine function, may cause infertility, and may promote breast cancer in women.
- Soy contains natural toxins known as "anti-nutrients", interfering with the enzymes you need to digest protein.
- Soy contains high levels of phytates (phytic acid), preventing the absorption of certain minerals, including calcium, magnesium, iron, and zinc.
- Soy contains goitrogens, a potent anti-thyroid compounds, thereby interfering with your thyroid function.
http://articles.mercola.com/sites/articles/archive/2010/09/18/soy-can-damage-your-health.aspx
http://wellnessmama.com/3684/is-soy-healthy/