Genistein is an isoflavone, which is a hormone-like substance found in soybeans. Numerous studies have shown that genistein is both a phytoestrogen and antioxidant, and it is most often used to treat conditions affected by an estrogen levels in the body. After numerous clinical studies, researchers in Finland concluded that people in Japan have lower rates of breast, ovarian, and prostate cancer because of the genistein contained in their diets, which are high in soy. Genistein binds itself in place of estrogen on receptors in cancerous cells that need this hormone to grow. Some studies have also shown that it helps regulate blood sugar and prevent the development of insulin resistance that can lead to diabetes and a host of disorders associated with this condition, including diabetic retinopathy.