One of the most controversial and confusing questions surrounding breast cancer is the effect of eating soy. Some studies say soy and the isoflavone genistein that it contains prevents breast cancer. Other studies say genistein is a risk factor for developing breast cancer. Breast cancer researcher Xiaohe Yang, PhD, associate professor with the North Carolina Central University Nutrition Research Program at the North Carolina Research Campus in Kannapolis, agrees with both sets of findings.
He has found in a mouse model that genistein, which is a phytoestrogen or natural estrogen found in plants, can act as a preventative agent against the development of breast cancer, especially when the exposure comes at puberty or earlier in life.
Later in life, adult women may be affected differently. Yang’s studies suggest breast cancer survivors or patients with erbB-2/Her2 and ER double positive tumors should be aware of the possibility that they could be “more vulnerable to the potential stimulation from genistein.”
“This does not change the healthy and beneficial effects of regular intake of soy food in a healthy population, especially for youngsters,” Yang emphasized. But women with a high risk of Her2 breast cancer or with ER double positive tumors should “avoid an unnecessary risk by limiting consumption of soy products and supplements.”
Read more about Yang’s breast cancer research.