Isoflavones from soy extracts are often used in highly concentrated food supplements as an alternative to hormone replacement therapy. However, due to the fact that they encourage estrogen activity, isoflavones are a focus of safety concerns about their potential to promote the growth of hormone-dependent cancer cells. For the study, the Austrian research team tested isoflavones for their effect on cell proliferation, cell death and cell cycle arrest.
Isoflavones were applied to 11 human cancer cell lines (representing cancers of the colon, prostate, breast, cervix, liver, pancreas, stomach and ovaries). The researchers then conducted tests to detect if any of the cancer cells were killed, or if the cancer cells were prevented from multiplying. They found that the isoflavones significantly reduced the proliferation activity of the treated cancer cell lines. No cell growth promotion was observed, but the researchers did observe cells dying and being programmed to die. They noted that genistein (found in soy) was the most potent isoflavone. They concluded that isoflavones do not promote the growth of human cancer cells; but instead cause decreased cell proliferation, and increased cell death and cell cycle arrest. They went on to state that these results indicate that isoflavones can be considered safe compounds.
Soy is a healing food that can be added to your diet to boost your nutritional health. If you have any fears around the issue of soy and cancer, talk to your healthcare provider.