Genistein is one of several known isoflavones. Isoflavones, such as genistein an daidzein, are found in a number of plants, with soybeans and soy products like tofu and textured vegetable protein being the primary food source. Soy isoflavones are a group of compounds found in and isolated from the soybean. Besides functioning as antioxidants, many isoflavones have been shown to interact with animal and human estrogen receptors, causing effects in the body similar to those caused by the hormone estrogen. Soy isoflavones also produce non-hormonal effects.