ABSTRACT
I. INTRODUCTION Breast cancer incidence and mortality are high in the western world compared to countries in Asia (World Cancer Research Fund and American Institute for Cancer Research, 1997). Also, within countries like in Finland and Italy, regional differences in cancer incidence occur and numerous immigrant studies also suggest that both lifestyle and diet are involved in causing these differences. We have postulated that the isoflavone-rich Asian diet as well as the original northern European diet with a high grain fiber intake-as well as intake of wild berries and some root vegetables rich in lignans-lowers the risk of breast cancer (Adlercreutz, 1990; Adlercreutz et al. 1982, 1986, 1987). Studies have now shown that phytoestrogens directly or indirectly alter the production, metabolism, and action at the cellular level of steroids and increase production of sex hormone binding globulin (SHBG) regulating the levels of biologically active unconjugated sex hormones. They may also play a role by modulating growth factor action. Furthermore, the intestine and its microflora seem to play a central role in mediating the beneficial effects of phytoestrogens and other phytochemicals on health (Adlercreutz, 1998a; Adlercreutz and Mazur, 1997; Kurzer and Xu, 1997).
