Phytoestrogens: dietary intake and excretion in postmenopausal Chinese women

Abstract

Objectives The aims of this study were to estimate the dietary intake of phytoestrogens and to measure urinary phytoestrogen excretion in postmenopausal Chinese women.Methods Postmenopausal Chinese women were recruited from the hormone replacement clinic of the Prince of Wales Hospital. Dietary intake of phytoestrogen-rich foods was estimated using a food frequency questionnaire. Urinary output of the isoflavonoids daidzein and genistein and the metabolite of daidzein, equol, was measured using high-performance liquid chromatography.Results The mean daily excretion of daidzein, genistein and equol was 3.24 (± 3.63), 1.47 (± 1.75) and 0.64 (± 1.53) μmol, respectively. The total mean daily isoflavonoid excretion was 5.36 (± 5.27) μmol.Conclusions Urinary excretion of isoflavonoid phytoestrogens in this Chinese population was lower than that reported in Japanese subjects. This may be due to the higher consumption of legumes, especially soy products, in the Japanese compared to the Chinese diet. The intake of green vegetables was higher in the Chinese subjects, and this food group may be the main contributor to their total phytoestrogen intake.