Tuesday July 7, 2015 (foodconsumer.org) -- Eating soy foods or dietary protein supplements like soy protein isolates may boost risk of breast cancer, according to a study conducted by Professor William G. Helferich from University of Illinois at Urbana-Champaign in Urbana, IL 61801, USA and colleagues.
And you may not have to eat soy foods like crazy to promote the growth of breast cancer. The study showed that genistein at 700 ppm and 500 ppm and 180 ppm in dietary soy protein isolate stimulated estrogen receptor-positive (ER+) MCF-7 (human breast cancer) tumor growth in athymic mice xenograft model. They were similar to17β-estradiol which also fastened the growth of MCF-7 tumors in treated mice.
When treatments with 17β-estradiol and a diet with 700 ppm genistein was discontinued, tumors regressed completely. But complete regression was not observed when treatment with a diet containing 500 ppm genistein or soy protein isolate was discontinued.
The researchers found higher accounts of epidermal growth factor receptor 2 (HER2) were produced in the genistein - and soy protein isolate (IPS) induced non-regressing tumors, compared to that in controls.
The study concluded that "Long-term consumption of low GEN doses (≤500 ppm) promotes MCF-7 tumor growth and results in GINR (genistein and IPS induced non-regressing) tumors with more aggressive and advanced growth phenotypes."
Genistein is a metabolite product derived from soy protein. ISP is commonly used for body building. Soy foods are commonly consumed by Asian people. It is not absolutely understood how genistein boosts the risk of breast cancer while it is well known that soy protein is weakly estrogenic. (David Liu)
Juan E. Andrade, Young H. Ju , Chandra Baker , Daniel R. Doerge and William G. Helferich , Long-term exposure to dietary sources of genistein induces estrogen-independence in the human breast cancer (MCF-7) xenograft model, Molecular Nutrition & Food Research, Volume 59, Issue 3, pages 413–423, March 2015
Photo credit: Chris 73 on wikipedia
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