Phyto-oestrogens: A potential role in the prevention of CHD?

Abstract

CHD is a major cause of morbidity and mortality in women. The incidence of CHD in premenopausal women is low but increases substantially after the menopause, and this difference suggests that endogenous oestrogens are cardioprotective. Observational prospective studies have consistently shown that exogenous oestrogens also lower CHD risk. The biological mechanisms by which endogenous and exogenous oestrogens exert their protective effect are multifactorial, affecting lipids, carbohydrate metabolism, body fat distribution and blood pressure. The prevention of CHD with oestrogen therapy i s therefore aimed both at correction of the traditional risk factors and at direct control of vessel structure and function. The wide international variation in rates of CHD together with the lower mortality in sub-groups of the population suggests that aconsiderable proportion of CHD may be prevented by dietary modification. Since phytooestrogens are structually similar to oestrogen, they have the potential to mimic its effects in vivo. The hypocholesterolaemic effects of soyabean protein (rich in phyto-oestrogen precursors) are well established, but the underlying mechanism and atherogenic potential of these changes are unknown. One isoflavone, genistein, has been shown in vitro to exert effects which may slow the development of atherosclerotic disease. However, further studies are required to determine the dose-related changes induced by phyto-oestrogens on serum lipoproteins, haemostasis and vascular function. Phyto-oestrogens: Oestrogens: Lignans: Soyabean: CHDAt any given age death rates in the UK for CHD in women are equivalent to the rates observed in men 10 years younger. Nevertheless, CHD is still a major cause of morbidity and mortality in women, and accounts for 23 % of female mortality (Williams, 1997). Women appear to be protected from CHD in the premenopausal years and this pre-v. post-menopausal difference in CHD risk suggests a protective role for endogenous oestrogens. Evidence for the influence of oestrogens on CHD risk factors is derived from two principal sources: (1) from changes in lipoprotein metabolism and other risk variables on progression to themenopause; (2) from the impact of oestrogen administration. Since lifelong use of exogenous oestrogen is required for cardioprotection (Grodstein et al. 1996), the long-term risk-benefit balance is crucial. Cross-cultural trends in the incidence rate of CHD, and the lower mortality observed in vegetarians (Key etal. 1996), suggest that a considerable proportion of CHD may be preventable through diet. Large-scale epidemiological studies have highlighted the potential benefits of increased fruit and vegetable intake, specifically in relation to antioxidant nutrients and phenolic flavonoids (Hertog et al. 1993; Gaziano el al. 1995;Pandey et al. 1995). Plant foods also contain nonsteroidal phyto-oestrogens, and these weakly oestrogenic compounds may harbour considerable potential to act as oestrogen agonists in vivo and may play a vital role in the prevention of CH...

Myocardial Akt Activation and Gender

“…Anecdotal evidence that cardiovascular disease risk may be lowered by estrogenic stimulation can be found in literature related to HRT (reviewed in Reference 3) and to diets that are rich in phytoestrogens. [47][48][49] Although most studies have been concerned with vascular effects and serum lipid levels, 50 it is reasonable to postulate that beneficial effects may also extend to the myocardium. These plant-based compounds include the isoflavones genistein and daidzein, which are naturally highly enriched in soybean products.…”

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

“…Many studies have associated phytoestrogen consumption and/or excretion with reduced risk for hormone-dependent cancers, as well as for coronary heart disease, symptoms of menopause and osteoporosis (Adlercreutz et al, 1992;Adlercreutz 1995;Gambacciani et al, 1997;Anderson et al, 1999;Cassidy and Griffin, 1999;Adlercreutz 2002;Bhathena and Velasquez, 2002;Clarkson, 2002;de Kleijn et al, 2002). 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).…”

“…Soy protein has been shown to lower, in a dose-dependent fashion, total cholesterol, LDL cholesterol, and triglycerides in both humans and animals (Anderson et al, 1995). Through this mechanism and others, phytoestrogens are thought to protect against coronary heart disease ( Clarkson and Anthony, 1998;Cassidy and Griffin, 1999). Additionally, phytoestrogen consumption has been linked loosely with relief of menopausal symptoms such as hot flashes, although the validity of these data are under debate (Adlercreutz et al, 1992;Vincent and Firzpatrick, 2000;Kim et al, 2002;Kurzer, 2002).…”

Genistein activates endothelial nitric oxide synthase in broiler pulmonary arterial endothelial cells by an Akt-dependent mechanism

“…Given the demonstrated risks to conventional estrogen therapy, phytoestrogens, a class of natural occurring estrogen, have received increasing attention because of their potentially protective roles against several types of chronic diseases, includeing cardiovascular diseases, osteoporosis and hormone-related cancer (Cassidy and Griffin, 1999;Lissin and Cooke, 2000). Among phytoestrogens, genistein and daidzein, two major isoflavones in soybeans are the well-studied due to their wide distribution.…”