Phyto-oestrogens and Western diseases.
Phyto-oestrogens and Western diseases.
Year: 1997
Authors: H Aldercreutz, W Mazur.
Publication Name: Annals Med.
Publication Details: Volume 29; 95.
Abstract:
In this extensive review paper, the authors describe the role of phytosterols in the prevention of diseases common in populations consuming a Western style diet with particular focus upon breast, colon and prostate cancer. Research studies assessed by authors suggest that the Western style diet, compared to a semivegetarian diet, may alter hormone production, metabolism or action at the cellular level. Lignans, found in highest quantity in flaxseed, and isoflavonoids found in soy products, are the subject of this review. These phytosterols are found in high plasma concentrations in populations living in areas with low rates of several diseases including coronary heart disease and cancer. Plant lignans and isoflavonoids are converted in the lower gut in humans into hormone-like compounds which influence sex hormone production, metabolism and biological activity. These effects result in changes in intracellular enzyme synthesis and activity, protein synthesis, growth factor action, cancer cell growth, differentiation and adhesion. Animal experiments have shown that both lignans and isoflavonoids may prevent the development of cancer as well as coronary heart disease. This paper discusses the biological effects and mechanism of action of phytoestrogens including their estrogenic and anti-estrogen effects and their role in steroid synthesis and activity. Descriptions are also provided in the areas of phytoestrogenic effects on tumors and the immune system. The preventive effects of phytoesterogens in breast, colon and prostatic cancer, in benign prostatic hyperplasia, in heart disease, menopause and osteoporosis are also extensively reviewed. Flaxseed lignans are found primarily in two forms, secoisolariciresinol and marairesinol. Diadzein and genistein are the principle forms of the isoflavonoids found in soybeans. In mammals, the lignans enterolactone and enterodial are formed from marairesinol and secoisolariciresinol by the action of intestinal bacteria. Following flaxseed feeding, the urinary and fecal excretion of enterolactone and enterodial increases in women. These phytosterols play significant inhibitory roles in cancer development in both the promotional and initiation stages of the disease. Many studies have shown that these phytoestrogens bind to estrogen receptors in cells and exhibit estrogen-like effects. In breast, colon and prostate cells, enterolactone and enterodial have also been found to have anti-estrogen effects. When present in high levels in the diet, these lignans may reduce inter-conversion of hormones such as androstenedione to estrone which may lower the risk for estrogen-dependent cancer. In regard to heart disease, the authors present research which supports hypolipidemic effects of isoflavonoids. In addition, genistein has been shown to be a powerful antioxidant in that it significantly reduces the susceptibility of LDL to oxidation. Genistein has also been found to have anti-thrombotic properties by reducing platelet aggregation. The authors conclude that experimental findings to date and epidemiological evidence strongly supports the view that phytoestrogens represent a family of compounds with potentially significant preventive and therapeutic effects in a number of human diseases.
