Many plants that are consumed contain phytoestrogens. Only a few published studies have examined the dietary intake of phytoestrogens in the general Western population. The potentially positive health effects of phytoestrogens might be of relevance to postmenopausal women. The aim of the present study was to estimate the intake of dietary isoflavones, coumestans and lignans by healthy Western postmenopausal women. For this purpose, we studied 964 postmenopausal, Caucasian women who participated in the Framingham Offspring Study and completed the Willett food-frequency questionnaire (FFQ). By searching the medical and agricultural literature and contacting experts, we identified food sources of phytoestrogens. The concentrations of the different isoflavones, coumestrol and lignans in each food in the FFQ were scored in seven categories and multiplied by the serving size of the food and the frequency of its consumption. The estimated daily median intake of the isoflavone daidzein was 39 microg (24-57 microg); of genistein, 70 microg (28-120 microg); of formononetin, 31 microg (13-44 microg); and of biochanin A, 6 microg (2-11 microg). Median total intake of isoflavones was 154 microg (99-235 microg). The main sources of isoflavones were beans and peas. The estimated daily intake of coumestans was 0.6 microg (0.2-1.7 microg), with broccoli as the main source. The estimated daily median intake of matairesinol was 19 microg (12-28 microg) and of secoisolariciresinol 560 microg (399-778 microg). The median total intake of lignans was 578 microg (416-796 microg). The main source of the lignans was fruits. The daily dietary intake of phytoestrogens in healthy postmenopausal Caucasian women in the United States is <1 mg.

Hypertension, central obesity and dyslipidemia are associated with high cardiovascular risk. Estrogen therapy in women has beneficial effects on some of these metabolic cardiovascular risk factors. It is not known whether dietary estrogens have similar effects, especially in Western populations. We studied the association between dietary phytoestrogen intake and metabolic cardiovascular risk factors in postmenopausal women. For this purpose, 939 postmenopausal women participating in the Framingham Offspring Study were included in this cross-sectional study. Mean blood pressure, waist-hip ratio (WHR) and lipoprotein levels were determined in quartile categories of dietary phytoestrogen (isoflavones and lignans) intake, determined by a food-frequency questionnaire. In addition, a metabolic syndrome score was defined according to WHO criteria (range 0-6). The WHR was lower in women in the highest quartile of intake of lignans compared with the lowest [-0.017; 95% confidence interval (CI) -0.030 to -0.0016]. In the highest quartile of intake of isoflavones, plasma triglyceride levels were 0.16 mmol/L lower (95% CI, -0.30 to -0.02) compared with the lowest quartile of isoflavones; for lignan intake, this difference was 0.23 mmol/L (95% CI, -0.37 to -0.09). In the highest quartile of isoflavone intake, the mean cardiovascular risk factor metabolic score was 0.43 points lower (95% CI, -0.70 to -0.16) than the lowest quartile. The difference in this score between the extreme quartiles of intake of lignans was -0.55 points (95% CI, -0.82 to -0.28). In conclusion, high intake of phytoestrogens in postmenopausal women appears to be associated with a favorable metabolic cardiovascular risk profile.

In this study, the authors investigated whether combined information on reproductive factors has additive value to the single reproductive factor age at menopause for assessing endogenous estrogen exposure and cardiovascular mortality risk in postmenopausal women. They conducted a population-based cohort study that included 9,450 postmenopausal women from Nijmegen, the Netherlands, who were aged 35--65 years at enrollment in 1975, with a median follow-up of 20.5 years. A Cox proportional hazards model and Receiver Operating Curves were used to analyze the data. Women aged 52 years or more at menopause had an 18% reduction in cardiovascular mortality (hazard ratio = 0.82, 95% confidence interval (CI): 0.69, 0.98) compared with those aged 44 years or less. Women with more than 18 years of exposure to endogenous estrogen had a statistically significant 20% reduction in cardiovascular mortality (hazard ratio = 0.80, 95 percent CI: 0.67, 0.96) compared with those who had 13 years of exposure or less. The area under the curve of the Receiver Operating Curves for the two models was identical (area under the curve = 0.67, 95 percent CI: 0.66, 0.68). This study shows that age at menopause is related to cardiovascular disease mortality and that a newly developed composite measure of endogenous estrogen exposure does not add to the predictive value of age at menopause for cardiovascular mortality.

Higher consumption of phytoestrogens might be protective against certain chronic diseases. Accurate quantification of habitual phytoestrogen intake is important for assessing associations between phytoestrogens and risk for certain diseases. The aim of this study was to estimate dietary intake of phytoestrogens in Dutch middle-aged and elderly women and to describe their main sources. Women were recruited between 1993 and 1997 and aged 50-69 y at enrollment (Prospect-EPIC; n = 17,357). A detailed food frequency questionnaire referring to the preceding year was filled in at recruitment. A literature search was conducted to obtain data regarding content of the isoflavones daidzein, genistein, formononetin, biochanin A, the coumestan coumesterol and the lignans matairesinol and secoisolariciresinol in relevant food items. Concentrations of each phytoestrogen in each food item were subsequently grouped by seven categories; group scores were multiplied by daily intakes of food items and then summed across food items to produce for each participant a total daily intake score for each phytoestrogen. Approximately 75% of participants were postmenopausal at recruitment. The mean age was 57 y. Geometric means of daily intake of daidzein, genistein, formononetin, biochanin A, coumesterol, matairesinol and secoisolariciresinol were 0.15, 0.16, 0.08, 0.001, <0.001, 0.07 and 0.93 mg, respectively. The main sources for isoflavones were peas and beans, nuts, grain products, coffee, tea and soy products. The main sources for coumestans were peas, beans and other vegetables. The main sources of lignans were grain products, fruit and alcoholic beverages (red and white wines). We conclude that intake levels of phytoestrogen in our study population are low; however, they are comparable with intake levels previously reported for other Western cohorts. In this population, phytoestrogen intake consisted largely of lignans.

No abstract