Phyto-oestrogen intake and plasma concentrations in South Asian and native British women resident in England

Phyto-oestrogens, naturally occurring hormone-like chemicals in plant food, may play a protective role against hormone-related chronic diseases. South Asian migrants in the UK have a lower incidence of hormone-related cancer than their hosts but the extent to which this difference may be due to phytoestrogen intake is not known. The aim was to compare habitual phytoestrogen intake in first-generation South Asian migrant women and native British women. South Asian (n 221) and native British women (n 50) were recruited from general practitioner lists and were asked to provide monthly 24 h recalls for a period of 1 year. An enhanced phytoestrogen database was compiled using data from a literature search and unpublished data. A sub-sample of South Asian women (n 100) and the native British women (n 40) also provided blood samples every 3 months during the 1-year period. The median daily intakes (mu g/d) of isoflavones (184.2 v. 333.9) and lignans (110.8 v. 148.8) were significantly lower in South Asians than in the native British (P < 0.001, P=0.04 respectively). There were no significant differences in mean plasma isoflavone levels (nmol/l) but plasma enterolactone was significantly lower in the South Asians (13.9 (sd17.5) v. 28.5 (SD23.3), P < 0.001). The main sources of phytoestrogens were bread and vegetables in both ethnic groups. Habitual phytoestrogen intake in South Asian and native British women was below 1 mg/d and was higher in the native British diet. The present study does not support the hypothesis that differences in phytoestrogen intake, or in circulating levels, could explain differences in hormone-related cancer risks between these two populations.