Dietary soy phytoestrogen effects on brain structure and aromatase in Long-Evans rats.

Phytoestrogens are estrogen-like (plant-derived) molecules that protect against age-related diseases (cardiovascular disease and osteoporosis), hormone-dependent (breast and prostate) cancers and selectively bind estrogen receptors. However, little is known about the influence of phytoestrogens on brain. Using diets containing either high phytoestrogen levels, derived from soy, or very low phytoestrogens we quantified phytoestrogen concentrations of daidzein, genistein and equol in brain. We found that dietary phytoestrogens: significantly decrease body and prostate weights, do not alter brain aromatase levels and significantly change during adulthood the structure of the sexually dimorphic brain region (i.e. anteroventral periventricular nucleus; AVPV) in male, but not in female rats. Since most commercial animal diets contain significant concentrations of phytoestrogens their influence on brain structure should be considered.