Various diet-derived substances have been shown to have anticancer effects both in vitro and in vivo. The isoflavonoid genistein (4′,5,7-trihydroxyisoflavone) is considered to be the active component of the chemopreventive effect of soy towards breast, prostate, and colon cancers.

Aamir Ahmad and co-workers, Wayne State University School of Medicine, USA, have studied the mechanism of action of genistein against human breast cancer cells. They found that genistein caused a dose- and time-dependent inhibition of the proliferation of cancer cells, but not normal cells. The cytotoxicity toward cancer cells is explained by the elevated levels of copper which is overexpressed in cancer tissues and cells. Genistein was shown target and mobilize endogenous Cu leading to prooxidant signaling and consequent cell death.

While the reason for high Cu levels in cancerous cells is still unknown, a simple remedy seems to be a diet rich in soy.

• Soy isoflavone genistein induces cell death in breast cancer cells through mobilization of endogenous copper ions and generation of reactive oxygen species
  M. F. Ullah, A. Ahmad, H. Zubair, H. Y. Khan, Z. Wang, F. H. Sarkar, S. M. Hadi,
  Mol. Nutr. Food Res. 2011.
  DOI: 10.1002/mnfr.201000329