Isoflavones are a class of plant-derived compounds mimicking estrogen activity in mammals. Genistein and daidzein are two of such phytoestrogens contained in soybeans. Efficacy against several diseases of soy-based diets and derivative nutraceutical products is still matter of debate, as well as their safety.
We applied repTOP™ ERE-Luc mice to the study of estrogen system modulation due to genistein and in general soy-based diet. After feeding mice with soy milk for one day, estrogen receptor activity was increased of about three folds above control. This was somehow expected based on data about pure genistein, but anyway confirmed that also the natural occurring compound, in the context of a dietary mixture, was biologically active. Surprisingly we observed that soy milk feeding over prolonged times is much stronger in inducing and sustaining estrogen receptor activity than the administration of the purified genistein or of a mixture of genistein and daidzein, the two main phytoestrogens present in soy milk.