The research, which is forecast to take five-years, will focus on the safety of phytoestrogens, the estrogen-like compounds in plants that are generally thought to be behind the the anti-cancer and cholesterol-lowering benefits that researchers have attributed to soy consumption in numerous studies.
The project is funded by an $8 million grant from the National Institutes of Health and will be led by William Helferich, a professor of food science and human nutrition, whose research has shown that high levels of the isoflavone genistein can promote the growth of cancerous cells in animal models representative of postmenopausal women with estrogen-dependent breast cancer.
"Under the grant, three groups will conduct preclinical investigations on animal models, looking for a balance of potential effectiveness and safety issues," said Helferich. "We will look at how different doses of isoflavones and the timing of exposure affect breast, brain and adipose tissues (fat). Another group will look at the mechanisms at work between isoflavones and estrogen receptors."
The scientists have decided to undertake this research on the basis that many dietary supplements and food additives contain much higher concentrations of isoflavones than are found in soy-based or supplemented food.
"Because phytoestrogens mimic estrogen, the supplements often are marketed to women as safe alternatives to hormone-replacement therapy, which has been linked to cardiovascular problems and dementia, for battling symptoms such as hot flushes," said the researchers, who want to look at the effects these high-dosage supplements are actually having on the body.
The researchers will initially concentrate their efforts on the biological effects of pure isoflavones, including genistein and equol, before moving on to look at the reactions of complex mixtures of soy isoflavones found in commercially available supplements.
Helferich discovered recently that isoflavones can block the effectiveness of tamoxifen by reducing estrogen-induced tumor growth. During this study, his lab will focus on breast cancer, looking at low-level chronic exposure to soy isoflavones and their influence on the progression of breast cancer from estrogen dependent to estrogen independent tumors.
Meanwhile, colleagues will concentrate on three other projects, investigating: adipose development and the potential for phytoestrogens to alter development and/or produce long-term changes in the amount and function of adipose tissue; the effects of phytoestrogens on brain tissue and cognitive function; patterns of gene activation affected by isoflavones through estrogen-dependent and estrogen-independent receptors in breast tumors, and gene regulation in breast tumor systems.