Phytoestrogens effects

Although there is some controversy about how much soy must be consumed to benefit from its phytoestrogen effect, it is beheved that two servings per day will modestly reduce menopausal symptoms and the risk of breast cancer. More than three servings may reduce cholesterol. Although it has yet to be proved that dietary soy will stop osteoporosis, a synthetic isoflavone, ipriflavone, has been used in Japan and Europe to treat osteoporosis. Large doses of soy (6-8 servings per day) are believed by some to help this condition as well. 

Henry LA, Witt DM. 2002. Resveratrol Phytoestrogen effects on reproductive physiology and behavior in female rats. Horm Behav 41 220-228. 

The North American Menopause Society position statement for treatment of mild menopause-associated vasomotor symptoms recommends first trying lifestyle changes, either alone or in combination with nonprescription remedies such as dietary isoflavones, black cohosh, or vitamin E. Studies suggest that there is a modest reduction in vasomotor symptoms with soy supplementation and that higher doses of soy isoflavones may be needed. Black cohosh does not have phytoestrogenic effects, and the evidence of its efficacy for menopausal symptoms is Dong quai, a traditional... 

Jenkins, D.J.A. C.W.C. Kendall M.A. D Costa C.-J. Jackson E. Vidgen W. Singer J.A. Silver-man G. Koumbridis J. Honey A.V. Rao, et al. Soy consumption and phytoestrogens Effect on serum prostate specific antigen when blood lipids and oxidized low-density lipoprotein are reduced in hyperlipidemic men./. Urol 2003, 169, 507-511. 

Another possibility deserving consideration is that some of the phytoestrogen effects may be attributable to properties that do not involve estrogen receptors, such as effects on enzymes, protein synthesis, cell proliferation, angiogenesis, calcium transport, Na /K adenosine triphosphatase, growth factor action, vascular smooth muscle cells, lipid oxidation, and cell differentiation. Some of these properties will be further discussed. 

Waldschlager, J., C. Bergemann, W. Ruth, U. Effmert, U. Jeschke, R.U. Richter, U. Kragl, B. Piechulla, and V. Briese. 2005. Flaxseed extracts with phytoestrogenic effects on a hormone recep>-tor-positive tumour cell line. Anticancer Res. 25(3A) 1817-1822. 

Isoflavones may be found in small amounts in soy-based infant formulas [10]. Isoflavones are found in whole soybeans and products including tofu, tempeh, and soy milk. Isoflavones are classified as both phytoestrogens (plant estrogens) and selective estrogen receptor modnlators. The phytoestrogenic effects of isoflavones have led to the use of soy foods and isoflavone supplements as alternatives to conventional hormone therapy. However, studies have found no long-term complications associated with isoflavones in infants fed soy-based formulas [10,17]. 

This review briefly summarises the available evidence on the relative potency of the phytoestrogens, and discusses the evidence that beneficial effects on human diseases may potentially arise from consumption of foodstuffs containing these compounds, with particular regard to those effects that have been suggested as possibly being related to the hormone-receptor mediated activities of the phytoestrogens. Certain causes for concern regarding these compounds are also addressed. 

Thus, it is apparent that soya, some soya products and linseed oil influence blood lipid levels, particularly cholesterol and LDL cholesterol. While the extent of the reduction appears to largely depend on an individual s initial serum cholesterol level, the maximum reductions observed are of the order of 10-15%. For hyperlipidemic individuals this may not be a marked reduction, but such an effect on the general population may well have a beneficial effect on the overall incidence of cardiovascular disease and atherosclerosis. The possibility that non-phytoestrogenic dietary components may contribute to the hypocholes-terolemic properties cannot, however, be discounted. Indeed, certain types of dietary fibre have been shown to have a hypolipidemic effect via their ability to increase faecal excretion rates. 

Thus, it is uncertain to what extent the apparent protective effects of fruit and vegetable consumption on risk of stomach cancer can be attributable to their phytoestrogen content. This appears not to have been studied directly, and other constituents such as ascorbic acid (vitamin C), a-tocopherol (vitamin E) and /1-carotene may be potentially protective. 

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