Abstract
Our diet and environment have changed rapidly since the start of industrialization. Our partially genetically determined behavior leads, in the affluent society, to the consumption of a diet rich in cholesterol, fat, energy, and salt and to a rapid increase in the incidence of so-called Western diseases. These diseases include all the major causes of death like various cancers and coronary heart disease. The industrially produced highly palatable diet contains too little essentially protective compounds, and our sedentary lifestyle, smoking, high alcohol consumption, and other behaviors further contribute to the development of disease. In fact cancer may be a relatively young disease going back to Hippocrates and ancient Greece about 2500 years ago, suggesting that evolution plays an important role.
In this presentation I will discuss the importance of the relations between phytoestrogens, mainly flavonoids and lignans, and steroids during evolution and the possible role of these evolutionary events and our intestinal microflora for adequate nutrition and availability of cancer protective compounds such as phytoestrogens.
Breast, endometrial, and prostate cancers are steroid hormone-dependent, and steroid hormone receptors have also been found in colon and other cancers. Estrogens play a definite role in the development of breast and endometrial cancer, but, in addition, they may have important roles with regard to prostate (1) and colon (2) cancer. After identification of the unknown phenolic compounds in urine (3–7), the structural similarities between the diphenolic lignans and isoflavonoids on one hand, and estrogens on the other hand and their very close molecular weights immediately suggested that they could interfere with steroid hormone metabolism or action at the cellular level or that they by themselves could have biological effects in the body. Then we found that postmenopausal breast cancer patients, living in Boston, Massachusetts, after one year's follow-up, had a very low excretion of lignans and somewhat lower equol in urine compared to vegetarians (8).
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