Daidzein is an isoflavone, which is a hormone-like substance found in soybeans. Daidzein is the second most plentiful isoflavone in soy, after genistein. Numerous studies have shown that, like genistein, daidzein is both a phytoestrogen and antioxidant, and it is most often used to treat conditions affected by an estrogen levels in the body.
Daidzein inhibits the growth of cancer by taking the place of estrogen on receptors in cancerous cells that need estrogen to grow.
Daidzein also inhibits the growth of tumors by forcing cells to differentiate normally, rather than the wild, exponential cell
growth seen in tumor cells. Daidzein has been shown to be especially effecting in checking the growth of leukemia cells and melanoma cells.