Phyto-oestrogens and Western Diseases

Abstract

Incidences of breast, colorectal and prostate cancer are high in the Western world compared to countries in Asia. We have postulated that the Western diet compared to the semivegetarian diet in some Asian countries may alter hormone production, metabolism or action at the cellular level by some biochemical mechanisms. Our interest has been focused on two groups of hormone-like diphenolic phyto-oestrogens of dietary origin, the lignans and isoflavonoids abundant in plasma of subjects living in areas with low cancer incidence. The precursors of the biologically active compounds detected in man are found in soybean products, whole-grain cereal food, seeds, and berries. The plant lignan and isoflavonoid glycosides are converted by intestinal bacteria to hormone-like compounds. The weakly oestrogenic diphenols formed influence sex-hormone production, metabolism and biological activity, intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, differentiation, cell adhesion and angiogenesis in such a way as to make them strong candidates for a role as natural cancer-protective compounds. Their effect on some of the most important steroid biosynthetic enzymes may result in beneficial modulation of hormone concentrations and action in the cells preventing development of cancer. Owing to their oestrogenic activity they reduce hot flushes and vaginal dryness in postmenopausal women and may to some degree inhibit osteoporosis, but alone they may be insufficient for complete protection. Soy intake prevents oxidation of the low-density lipoproteins in vitro when isolated from soy-treated individuals and affect favourably plasma lipid concentrations. Animal experiments provide evidence suggesting that both lignans and isoflavonoids may prevent the development of cancer as well as atherosclerosis. However, in some of these experiments it has not been possible to separate the phyto-oestrogen effect from the effect of other components in the food. The isoflavonoids and lignans may play a significant inhibitory role in cancer development particularly in the promotional phase of the disease, but recent evidence points also to a role in the initiation stage of carcinogenesis. At present, however, no definite recommendations can be made as to the dietary amounts needed for prevention of disease. This review deals with all the above-mentioned aspects of phyto-oestrogens.

Urinary phytoestrogen concentrations in the U.S. population (1999–2000)

“…For example, soy ingestion in rodents has been associated with a decrease in the growth of breast cancer tumors (Barnes et al, 1990), and flaxseed ingestion protects against both breast and colon cancers in rodents Thompson, 1991, 1992). Similar studies in humans have shown that dietary consumption of phytoestrogens decreases the risk for breast cancer (Adlercreutz et al, 1987(Adlercreutz et al, , 1997Ingram et al, 1997;Adlercreutz and Mazur, 1997) and prostate cancer (Severson et al, 1989). In addition, links have been shown between phytoestrogen consumption and colon cancer although they remain controversial (Messina and Bennink, 1998).…”

Effects of dietary soy protein on iliac and carotid artery atherosclerosis and gene expression in male monkeys

“…The major components of soy protein isolate (SPI) most often associated with the suggested cardiovascular benefits of soy are the protein/peptide fractions and the isoflavones (IF). IF are estrogen-like compounds found in soy beans, as well as many legumes and grains (5). The most abundant IF in soy products are daidzein, genistein, and glycitein.…”

“…The most abundant IF in soy products are daidzein, genistein, and glycitein. In addition, IF metabolites, such as equol, may contribute to the biological activity of dietary IF (5). IF are structurally similar to estradiol and known to interact with estrogen receptors, imparting estrogen agonist/antagonist activities in vitro and in vivo (6).…”

Urinary isoflavonoid excretion is inversely associated with the ratio of protein to dietary fibre intake in young women

“…Isoflavones possess weak oestrogenic and antioestrogenic activities, and may reduce the risk of chronic diseases such as hormone-sensitive cancers and cardiovascular disease (Adlercreutz & Mazur, 1997).…”