ABSTRACT
Natural estrogens are involved in a multiplicity of programmed events in target tissues such as the uterus, breast, pituitary gland and hormone-responsive tumors. The initiation of estrogen action by all of the estrogens is considered to be the same in each target tissue. Estrogen first binds to the nuclear ER, then an estrogenic ligand causes a conformational change that encourages dimerization and interaction with either specific DNA sequences or a protein-protein interaction with activator protein-1 (AP-1) or specificity protein 1 (SP1) sites in the promoter region of estrogen-responsive genes3. These events herald the biological effects of estrogen in the specific target tissue or tumor. A small percentage (2-3%) of ERs are located on the cell membrane and contribute to non-genomic
Figure 1 Phytoestrogens: scientific research areas
Within the past several years, the relationship between diet and health has been accepted by the mainstream nutrition community and, in this connection, interest in the physiological role of bioactive compounds present in plants has dramatically increased over the last decade. As a complex mixture of chemicals, foods provide essential nutrients, requisite calories and other physiologically active constituents that may be useful for life and health. A new paradigm for ‘optimal nutrition’ may be evolving that would identify physiologically active components that contribute to disease prevention. Thus, the functional foods concept unifies the medical, nutritional and food sciences (Figure 1). Collectively, plants contain several different families of natural bioactive products, among which are
phytochemicals or polyphenols. These are the largest category of phytochemicals and the most widely distributed in the plant kingdom7.
