Influence of human infant formulas containing phytoestrogens on brain aromatase activity in adult rats.

The biosynthesis of estrogens from androgen precursors is regulated by the aromatase enzyme, and estrogenic molecules are known to be significant factors in the formation of sexually dimorphic brain structures in the anterior hypothalamus. Phytoestrogens have been shown to inhibit aromatase enzyme activity in peripheral tissues. In this study, phytoestrogen-containing human infant formulas were examined to determine whether these estrogen mimics influence brain aromatase levels in adult rats.