Equol-producing ability of Polish postmenopausal women and the dietary determinants of S-(-) equol formation

Background. Equol (Eq) is the most potent soy isoflavone metabolite but individual people differ in their ability to produce it. It has been highlighted that some dietary factors may play a role in Eq formation. This study examines the hypothesis that there are specific dietary factors that determine the ability to produce Eq in Polish postmenopausal women. Moreover, Eq-producing phenotypes were also identified among. Thirtythree healthy, non-smoking Polish postmenopausal women aged 48–68 years were recruited. The women were asked to take soy isoflavone (100 mg/day) for three consecutive days. Mean daily intakes of energy and nutrients were estimated from 3-day food records. After dietary intervention, 24-hour urine samples were collected. Urinary isoflavones and their metabolites were measured using liquid chromatography with the tandem mass spectrometry method. Eq producers were defined using the cut-off of log10-transformed urinary Eq: daidzein (De) ratios > −1.75. 43.75% of participants excreted Eq.
Results. The mean urine Eq excretion ±standard error, corrected for urinary creatinine (Cr), was 41.1 ±9.6 μmol/g-Cr in the Eq producers and 0.2 ±0.07 μmol/g-Cr in the nonproducers. Multivariable logistic regression analysis showed that participants who reported higher pulses intake were more likely to be Eq producers after adjusting for age, BMI and years after menopause (odds ratio: OR = 1.109, 95% CI: 1.033; 1.190; p = 0.004).
Conclusions. In summary, higher pulses intake was associated with the ability to produce Eq among Polish postmenopausal women.