Demographic, anthropometric, and lifestyle factors and dietary intakes in relation to daidzein-metabolizing phenotypes among premenopausal women in the United States

BACKGROUND: The soy isoflavone daidzein is metabolized to equol and O-desmethylangolensin (ODMA) by intestinal bacteria in [almost equal to]30-50% and 80-90% of persons, respectively. Studies suggest beneficial health effects associated with daidzein-metabolizing phenotypes; thus, assessing their determinants is an important goal. OBJECTIVE: We evaluated relations between daidzein-metabolizing phenotypes and demographic, anthropometric, lifestyle, and dietary factors among premenopausal women in the United States. DESIGN: Two hundred women provided a first-void urine sample after a 3-d soy challenge and completed a health and demographics questionnaire, physical activity questionnaire, food-frequency questionnaire, and 3-d food record. Urine samples were measured for isoflavones by gas chromatography-mass spectrometry to determine daidzein-metabolizing phenotypes. RESULTS: Fifty-five (27.5%) and 182 (91%) women had detectable concentrations of urinary equol and ODMA (>87.5 ng/mL), respectively, and were classed as producers of these metabolites. Compared with nonproducers, equol producers were more likely (P