Intakes and sources of soya foods and isoflavones in a UK population cohort study (EPIC-Norfolk)

Abstract

Background: It has been suggested that the consumption of a diet rich in phytoestrogens might protect against a variety of diseases common in Western societies. However, there are little available data on the food sources or distribution of intake in the UK diet. Objective: To estimate the average intake and range of soya foods and isoflavones in a population-based cohort and to provide data on isoflavone consumption by food group. Subjects: Men and women (11 843) from the Norfolk arm of the European Prospective Investigation into Cancer and Nutrition (EPIC). Methods: Dietary daidzein and genistein intakes were obtained from 7-day food diaries, completed by participants between 1993 and 1998 and calculated from an in-house food composition database. Energy and anthropometric measurements were also carried out. Results: Average daily isoflavone intakes for both men and women were less than 1 mg (interquartile range (IQR) men: 0.39-0.82 mg; women: 0.30-0.64 mg). However, in soya-consumers, average daily intakes were higher: 8.6 mg in women (IQR: 2.28-10.72 mg) and 7.5 mg in men (IQR: 2.22-9.17 mg). In both men and women, bread and bread rolls made the highest contribution to isoflavone intake -62.5 and 53.0%, respectively. In soya-consuming men and women, vegetable dishes and milks were the main contributors -25.0 and 38.5% in men and 38.5% and 26.0% in women, respectively. Conclusions: Isoflavone intake is low in the UK but may be an underestimate due to soya added to commercial products. Future analyses of the isoflavone and lignan content of basic ingredient foods and commercial items commonly consumed in the UK diet will enable more accurate estimates of phytoestrogen intake to be made. The ability to estimate isoflavone intake in Western populations more accurately will enable investigations to be conducted into the suggested beneficial effects of phytoestrogens on health.

The DietCompLyf study: A prospective cohort study of breast cancer survival and phytoestrogen consumption

“…Older women tended to favour lignan-containing, younger women isoflavone-containing, foods. The increased intake of isoflavones in younger women agrees with other UK data [3] and higher lignan consumption in older women has also been reported elsewhere [25]. However, the differences in lignan consumption across the different age groups has not (to our knowledge) previously been reported for UK breast cancer patients.…”

“…Vegetarianism alone did not account for disparities in tofu/soya meal consumption; therefore it is hypothesized that this dietary change may reflect recent changes in health, diet and food availability and/or a combination thereof. It was expected that bread and soya milk consumption would provide the majority of isoflavones consumed in a UK diet [3], yet only 1% of the patients in this subset reportedly drank soya milk. The heterogeneity (bread containing soy and linseed for example being contained in the same group as standard brown bread; genistein contents of 6,807 and 246 µg/100g respectively) was not controlled for [26].…”

“…Intakes vary significantly between Eastern and Western diets. Eastern diets typically include soy-based foods which are rich in isoflavones, one of the main groups of phytoestrogens whilst Western diets more typically obtain isoflavones from legumes, coffee, nuts, bread and soya milk [3]. Lignans are the most common phytoestrogens found in UK foods (e.g., beverages, cereals, cruciferous vegetables and some fruits), yet isoflavones account for the greatest phytoestrogen intakes due to the use of soya in bread production [4].…”

Phytoestrogen Content of Foods of Animal Origin: Dairy Products, Eggs, Meat, Fish, and Seafood

“…Consequently, the contribution to total phytoestrogen exposure is often neglected (32). The data presented in this study are the first comprehensive investigation of phytoestrogens in animal products and will allow for a more accurate determination of exposure to dietary phytoestrogens from foods.…”

“…However, not all epidemiological and surveillance studies have biological samples available, and many studies have relied on reports of food intake and associated phytoestrogen databases to assess phytoestrogen exposure in relation to disease risk (28)(29)(30)(31)(32). Previous food analyses have mainly been limited to isoflavones in fruit, vegetables, nuts, and seeds, and there is little data available for lignans and animal foods (33-36) (37).…”