Inter- and intra-individual variation in urinary excretion of daidzein and equol in female Japanese.
OBJECTIVE
To evaluate the representativeness of single measurement of urinary soy-isoflavone concentrations for the assessment of long-term intake levels.


METHODS
Five urine samples taken from 14 Japanese female subjects over 2-3 months were measured for daidzein and equol by gas chromatography-mass spectrometry (GC-MS).


RESULTS
Geometric mean daidzein and equol concentrations of 14 subjects were 582 and 2.66 μg/g creatinine, respectively. Intra-class correlation coefficients for daidzein and equol were 0.355 (95% CI: 0.130-0.649) and 0.741 (0.551-0.891), respectively.


CONCLUSIONS
Single measurement of urinary equol is effective for the assessment of long-term equol status of Japanese subject while that of daidzein is not.
Department of Environmental Studies, University of Tokyo , Chiba , Japan.
Yayoi
Y
Suzuki
Aya
A
Hisada
Jun
J
Yoshinaga
D000328:Adult; D044466:Asian People; D060754:Equol / Q000652:urine*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007529:Isoflavones / Q000652:urine*; D007564:Japan; D013997:Time Factors; D055815:Young Adult
D007529:Isoflavones; D060754:Equol; C004742:daidzein
Breast cancer; chemical carcinogenesis; environmental pollution/ecotoxicology