Soy Protein and Women’s Health
In the age of medicinal drugs and quick fixes for every health condition, safe, efficacious, natural alternatives to hormone replacement therapy (HRT) such as dietary interventions are often overlooked. Women’s health is one area where small dietary changes may be an adjunct to prevention and treatment of various problems. The inclusion of soy foods in the diet may constitute an example of an alternative or complementary approach to promote women’s health.
• Coronary Heart Disease. Pre-menopausal women have a lower risk of CHD than men of the same age. However, following menopause, a woman’s risk is comparable to a man’s risk. One of the factors contributing to this delay in CHD in women relates to the production of estrogen, an endogenous cardioprotectant.
Observational studies and clinical evidence support the use of soy in preventing heart disease in all persons, specifically post-menopausal women. Setchell (2001) suggested that soy isoflavones resemble selective estrogen receptor modulators (SERMs) in adults and thus appear to protect women from CHD through mechanisms similar to that of estrogen. In addition, soy protein may reflect its impact on several types of lipoproteins, improvement in vascular health and reactivity, protection from oxidative damage, reduction of inflammation, and lowering of blood pressure; yet safety and efficacy of soy protein as a cardioprotectant remain to be sufficiently demonstrated in large, at-risk populations (Park et al., 2005).
• Menopause. Support for the use of soy foods to treat menopause symptoms has also been found. It is especially attractive for women who cannot or will not use HRT. Since the safety of HRT is questionable, especially for women who have a history of breast cancer, dietary soy may provide an alternative. The phytoestrogens found in soy have been shown to have estrogenic effects, which may act to substitute for the declining estrogen levels in women after menopause (Albertazzi and Purdie, 2002). However, earlier clinical data seem to support the inclusion of two to three servings of soy foods per day with naturally occurring isoflavones rather than using soy isoflavone supplements (Mackey and Eden, 1998).
• Breast Cancer. One of the most provocative areas of soy research lies in the realm of neoplastic disease. Interest is spurred by findings that populations with high consumption of soy foods seem to have lower rates of breast, uterine, and colon cancers than societies with low soy food intakes. Despite many limitations in the epidemiologic and animal data, there remains intriguing support for the hypothesis that food components, particularly soy food and vegetable intake, are associated with a reduced risk of breast cancer (Greenwald, 2004). Genistein and other soy isoflavones are hypothesized to account for most of the cancer-protection properties of soy foods by inhibiting estrogen receptor–sensitive cell growth. Although the evidence for soy consumption in cancer reduction is inconclusive and divided, some research is suggestive of various chemoprotective properties of soy.
• Diabetes. Among the leading disease-caused fatalities in the United States, diabetes is ranked fifth, and diabetics are at a greater risk for multiple and concurrent health problems than non-diabetics. Unfortunately for diabetic women, there is a greater frequency of complications than are seen in diabetic men. The risk for cardiovascular disease (CVD), which is already higher among diabetics, is even higher for diabetic women than for men. Because of these additional complications, it may be important for diabetic women to take advantage of dietary adjustments, such as consuming soy foods, toward reducing some of their health risks. For example, dietary soy may lower postprandial glucose levels, contribute to improved insulin levels and insulin sensitivity, reduce hyperglycemia, and possibly promote reduction in the reliance on medications to control and stabilize blood glucose levels, as well as modulate plasma lipid profile and concomitantly reduce a woman’s risk of CVD (Friedman and Brandon, 2001).
There are many popular approaches to the application of alternative and complementary medicine interventions for women’s health problems. Increased soy consumption appears to be one avenue for safe and effective augmentation of mainstream medical therapy. Future research in personalized nutrition and expanded investigations in nutrigenomics may reveal additional health benefits of soy consumption.
by JAMES W. ANDERSON, M.D.
Clinical Professor, Metabolic Research
University of Kentucky, Lexington
by M. KATHRYN PATTERSON
Graduate Research Associate
University of Kentucky, Lexington
Albertazzi, P. and Purdie, D. 2002. The nature and utility of the phytoestrogens: A review of the evidence. Maturitas 42(3): 173-185.
Friedman, M. and Brandon, D.L. 2001. Nutritional and health benefits of soy proteins. J Agric. Food Chem. 49: 1069-1086.
Greenwald P. 2004. Clinical trials in cancer prevention: Current results and perspectives for the future. J. Nutr. 134: 3507S-3512S.
Mackey, R. and Eden, J. 1998. Phytoestrogens and the menopause. Climacteric 1: 302-308.
Park, D., Huang, T., and Frishman, W.H. 2005. Phytoestrogens as cardioprotective agents. Cardiol. Rev. 13: 13-17.
Setchell, K.D. 2001. Soy isoflavones—Benefits and risks from nature’s selective estrogen receptor modulators (SERMs). J. Am. Coll. Nutr. 20: 354S-362S.