Identification of the isoflavonic phytoestrogen daidzein in human urine

The identification by gas chromatography-mass spectrometry of the isoflavonic phytoestrogen daidzein [7-hydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one] for the first time in human urine is described. The metabolism and effect on reproduction of isoflavones in animals and the possible significance of phytoestrogens in man is discussed. Preliminary results on the quantitative excretion of daidzein in female subjects consuming different diets are also reported.