Impact of Dietary and Other Factors Including Iodine Sufficiency Status on the Levels of Urinary Phytoestrogens

Background and aims: Data from National Health and Nutrition Examination Survey for 2007-2010 were used to evaluate factors that affect observed variability in urinary phytoestrogens. Methods: Data for six phytoestrogen variables, namely, daidzein (DAZ), o-desmethylangolensin (DMA), equol (EQU), enterodiol (ETD), enterolactone (ETL), and genistein (GNS) were available for analyses. Regression models for log10 transformed values of these six phytoestrogens as dependent variables and gender, race/ethnicity, smoking status, iodine sufficiency status, body mass index, poverty income ratio, urine creatinine, consumption of selected foods, and selected total nutrient variables as independent variables were fitted. Results: Males had statistically significantly higher levels of DAZ, DMA, EQU, ETD, and ETL than females (p ≤0.03). Non-Hispanic whites had statistically significantly higher levels of DMA, EQU, and ETD (p< 0.01) than Mexican Americans. NHW had statistically significantly higher levels of EQU and ETD (p< 0.01) than non-Hispanic blacks. Smoking was associated with 42.9%, 18.2%, 41%, and 72% lower levels of DMA, EQU, ETD, and ETL respectively as compared to nonsmokers. Iodine deficiency was associated with 47%, 55.6%, 88.6%, 4.5%, 17.8%, and 29.2% lower levels of DAZ, DMA, EQU, ETD, ETL, and GNS respectively. Levels of EQU were positively associated with consumptions of milk products and seeds. Consumption of legumes, nuts, and grains had positive association with DAZ, DMA, and GNS. Levels of DAZ, DMA, and ETL were positively associated with consumption of eggs. Finally, there were positive associations between the consumptions of fish and seeds with the levels of ETD. Conclusion: In conclusion, both smoking and iodine deficiency may affect metabolism of selected phytoestrogens.