In a commentary article published on March 18, 2016 in the in the peer-reviewed journal Nature Reviews Endocrinology, researchers Frederick S. vom Saal and Wade V. Welshons from the University of Missouri, U.S., discuss the findings of a recently published study showing the following: 1) Women with increased urinary bisphenol A (BPA, CAS 80-05-7) levels had reduced rates of successful pregnancies when undergoing in vitro fertilization (IVF), and 2) eating soy foods appeared to protect women from the negative effect of BPA on IVF (FPF reported).
Regarding the first finding, vom Saal and Welshons emphasize the study’s significance in adding to mounting evidence that BPA is a reproductive toxicant at daily low-level exposures. Therefore, the authors suggest that the U.S. Food and Drug Administration (FDA) reconsiders the assumption that levels of bioactive BPA circulating in people’s blood are negligible and revisits its current safe levels.
Regarding the second finding, the authors note that isoflavone compounds in soy fall within the category of estrogenic environmental endocrine disruptors, just like BPA. This suggests that manmade (e.g. BPA) and naturally occurring (e.g. isoflavone) environmental estrogens “differ in their potential to affect gene activity in tissues targeted by estrogen, and are known as selective estrogen receptor modulators.” Therefore, soy and BPA “can have dramatically different effects in different tissues at low and high doses.” Vom Saal and Welshons conlude that “diet, dietary supplements and a multitude of environmental stressors can modify the response to drugs or toxic chemicals such as BPA” and therefore must be taken into account in these analyses.
Vom Saal, F.S. & Welshons, W.V. (2016). “Endocrine disruptors: Manmade and natural oestrogens: opposite effects on assisted reproduction.” Nature Reviews Endocrinology (published online March 18, 2016).
Chavarro, J.E. et al. (2016). “Soy intake modifies the relation between urinary bisphenol A concentrations and pregnancy outcomes among women undergoing assisted reproduction.” The Journal of Clinical Endocrinology and Metabolism (published online January 27, 2016).