Isoflavones are phytoestrogens that belong to the class of flavonoids. Phytoestrogens are plant molecules derived from structurally and / or functionally resemble mammalian estrogen. These non-nutrients are defined endocrine disrupters or endocrine disruptors, capable of modulating the endocrine metabolism, generally through their binding to the nuclear receptors in human. The active ingredients contained in the isoflavone genistein are responsible for this activity, daidzein and glycitein, substances that act like hormones weak in the absence of estrogen. However, if estrogen is present or counteract some effects on the breast and endometrium, strengthening those on bone density. In particular, genistein shows modulatory activity on estrogen receptors alpha and beta.