Urinary Phytoestrogen Metabolites Positively Correlate with Serum 25(OH)D Level Based on National Health and Nutrition Examination Survey 2009–2010

Abstract

Studies showed that vitamin D (25-hydroxyvitamin D) level in the human blood circulation could be affected by exogenous estrogen exposure. This study aims to explore the relationships between urinary phytoestrogens metabolites and serum total 25(OH)D in general population, urinary phytoestrogens metabolites (daidzein, enterodiol, enterolactone, equol, genistein and o-desmethylangolensin). Totally 2,609 adults 6 y old from the 2009-2010 National Health and Nutrition Examination Surveys (NHANES) were recruited into the cross-sectional analyses and information including demographic, socioeconomic, examinations and laboratory test were collected. All analyses were performed using Stata13.0, one-way analysis of variance and multivariable regression were utilised according to data characteristics, respectively. It showed that age, race, education level, body mass index (BMI), and sampling season had significant effects on serum 25(OH)D level (all p,0.001). In the whole population, urinary enterodiol and equol were significantly positively associated with serum total 25(OH)D level (b50.86, 95%CI50.08-1.65, p,0.05; b51.68, 95%CI50.91-2.45, p,0.001). Equol was also found significantly positively correlated with total 25(OH)D in both female and male separately (b51.69, 95%CI50.51-2.87, p,0.05; b51.66, 95%CI50.63-2.69, p,0.05). Phytoestrogen concentrations in the urinary and 25(OH)D levels in the serum had proved a positive correlation in our study, which provide theoretical basis and reference for the dietary nutrient intake in the population.

Perspective: Observational Studies Involving Low-Soy Intake Populations Have Limited Ability for Providing Insight into the Health Effects of Soybean Isoflavones

“…Observational studies in Asian populations involve a wide range of isoflavone consumption based on varying intakes of soy foods. In contrast, observational studies involving low-soy intake populations, which include most non-Asian populations, involve much lower isoflavone intakes and thus, a much smaller intake range [ [7] , [8] , [9] , [10] , [11] ]. In this paper, we suggest that the utility of these studies for providing insight into the health effects of isoflavones (and indirectly soy foods) is questionable because isoflavone intake is too low and intake ranges too small to assess reasonable and relevant dose–response relationships.…”