"Vegetarians have long championed soy foods as the "ideal" source of protein despite the scientific facts that disprove the notion. Textured soy protein, which is more widely used in packaged and refined foods and meat products (hamburger extender) than most of us ever imagined, now has three antinutrients that should make anyone think twice before making it a major part of the diet. The three antinutrients are: (1) a large amount of phytic acid, which binds up and prevents absorption of minerals, especially zinc, calcium, and magnesium needed by the body; (2) trypsin inhibitors, which cannot be refined out of the soy mash (trypsin is an important enzyme in digestion); (3) isoflavones, genestein and daidzein, three phytochemicals that have now been shown to have antithyroid activity.... [Researchers found] that soy isoflavones, which are now being especially hyped for possible anticancer activity, are the most potent of the thyroid inhibitors followed by daidzein and then genistein. In a previous study, the team of plant chemical researchers had found similar antithyroid activity in some known bioflavanoids, including...quercertin. Most of the bioflavanoids, however, have not been found to inhibit thyroid function to any detrimental degree....No other dietary staple has so many antinutrient drawbacks as soy. Conversely, no other food has so many public relations firms and lobbyists working for it."
This may be difficult to read, but go over it carefully. If you can get through it and retain it, it should stick with you when you're looking at ingredient labels in the grocery store, and you see soy products listed there. Those are just the antinutrients, too; the worst of the products. There's also the high estrogen content worth considering.