SOYBEAN PHYTOESTROGEN INTAKE AND CANCER RISK

Because many Western diseases are hormone-dependent cancers, we have p ostulated that the Western diet, compared with a vegetarian or semi-ve getarian diet, may alter hormone production, metabolism or action at t he cellular level. Recently, our interest has been focused on the canc er-protective role of some hormone-like diphenolic phytoestrogens of d ietary origin, the lignans and isoflavonoids. The precursors of the bi ologically active compounds originate in soybean products (mainly isof lavonoids but also lignans), as well as whole grain cereals, seeds, pr obably berries and nuts (mainly lignans). The plant lignan and isoflav onoid glycosides are converted by intestinal bacteria to hormone-like compounds with weak estrogenic and antioxidative activity; they have n ow been shown to influence not only sex hormone metabolism and biologi cal activity but also intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, differentiation and angi ogenesis, making them strong candidates for a role as natural cancer p rotective compounds. Epidemiological investigations support this hypot hesis, because the highest levels of these compounds are found in coun tries or regions with low cancer incidence. This report is a review of results that suggest that the diphenolic isoflavonoids and lignans ar e natural cancer-protective compounds.