Dietary phytoestrogens and breast cancer risk
These researchers found no protective effect of dietary phytoestrogens (lignans and isoflavones) on breast cancer. However, if I might recall the research that suggested no protective effect of fiber on colon cancer risk. In both these cases, I could mutate the popular saying into “It’s the flora, stupid!!”
In neither of these studies were the participants stratified for GI flora. In both situations, the presence of a healthy bacterial flora that converts the protective compound (soluble dietary fiber into short chain fatty acids like butyrate, isoflavones and lignans into equols and enterolactones, respectively) into its active form may be the mechanism by which these compounds protect the body.
Just another example of the complex and important interactions between different aspects of human (and, in this case bacterial…) physiology that are many times missed by researchers.
AJCN — Abstracts: Keinan-Boker et al. 79 (2): 282 –