Dietary phytoestrogen intake in mid-life Australian-born women: relationship to health variables

Objectives: To estimate the dietary intake of isoflavone-rich foods in a population-based cohort of Australia-born women, and to investigate whether a high intake of isoflavone-rich foods is associated with health-related variables. Method: The study considered a population-based cohort of Australian-born women aged 51-62 years, with interviews, blood and physical measurements taken in their own homes. Food frequency questionnaires included usual eating habits and isoflavone-rich foods. Results: In total, 354 women (98%) returned both dietary questionnaires. Some 222 women (62%) reported consuming isoflavone-rich foods. Soy breads and milk provided the most servings per month. The mean intake of isoflavones calculated from soy beans, soy grits, tofu, soy milk, and soy and linseed bread in the whole cohort was 17 (standard deviation 35, range 0-340) mg/day. Fifty-one women (14%) consumed > 40 mg isoflavone/day. Compared with the rest of the cohort they had higher intakes of fruit, energy, protein, vitamins and minerals; ate a greater variety of vegetables; were more likely to exercise; were less likely to smoke; had lower mean body mass index, waist and hip measures and higher bone mineral density of the femoral neck; and had lower negative mood scores (all p < 0.05). Conclusion: Australian-born women in Melbourne have a wide range of intake of isoflavone-rich foods. For those with a high intake it seems to be one component of a healthier life-style. It is thus not possible to assign particular health benefits to the one dietary component.