title: Dietary and lifestyle correlates of urinary excretion status of equol in Japanese women.
abstract: The isoflavone metabolite equol has been identified in urine or blood samples in some but not all humans. In this cross-sectional study, we examined the association between lifestyle, including diet, and the urinary excretion of equol. Study subjects were 419 Japanese women who were recruited from a breast cancer screening center. Each woman responded to a self-administered questionnaire seeking information about health and lifestyle factors. Diet was assessed by a validated semiquantitative food frequency questionnaire. Urinary isoflavones were measured using spot urine samples. Equol was detected in the urine of 84 (20.0%) women. After controlling for covariates, it was found that dairy product intake was significantly lower in those who excreted detectable equol levels in urine than in those who did not. Because equol is derived from daidzein, individuals with low intake of daidzein may produce undetectable levels of equol. To account for this, the study subjects were restricted to 163 women with urinary daidzein levels of 10 nmol/mg creatinine or higher. The association of equol excretion with dairy product intake remained significant. Demographic factors, smoking status, and menstrual and reproductive factors were unrelated to equol excretion. These data suggest that dairy product intake may be associated with the production of equol.
authors.affiliation: Department of Epidemiology & Preventive Medicine, Gifu University Graduate School of Medicine, Gifu, Japan. chisato@gifu-u.ac.jp
authors.forename: Chisato
authors.initials: C
authors.lastname: Nagata
authors.forename: Tomomi
authors.initials: T
authors.lastname: Ueno
authors.forename: Shigeto
authors.initials: S
authors.lastname: Uchiyama
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Nagao
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Chiken
authors.initials: C
authors.lastname: Shibuya
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Kashiki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003611:Dairy Products / Q000009:adverse effects; D004032:Diet; D060754:Equol; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000378:metabolism / Q000652:urine*; D007564:Japan; D008019:Life Style; D008597:Menstrual Cycle; D008875:Middle Aged; D017698:Postmenopause; D012907:Smoking; D011795:Surveys and Questionnaires
chemical_list: C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D007529:Isoflavones; D060754:Equol; C004742:daidzein