Objective: To evaluate relations between equol-producing phenotype and serum sex hormones among adults in Beijing.
Methods: 90 male and 90 female adults participated in a cross-sectional study and provided twice 24h urine samples on a regular diet and after 3-d soy isoflavone challenge respectively. A health and demographics questionnaire, and 2 days food record were completed before the urine collection. Isoflavones and their metabolites in urine were measured to determine equol phenotype by HPLC.
Results: The serum total testosterone level of the male and the serum estradiol and progesterone levels among the female participants were no significant differences between the equol producers and non-producers (P > 0.05). There were negative correlations between urinary total isoflavone, daidzein, equol, O-desmethylangolensinl, glysitein, dihydroglysitein levels and serum total testosterone concentration among the male equol producers on a regular diet (r = -0.29 - -0.36, P < 0.05). There were no significant correlations between urinary isoflavonoid excretion and serum estradiol and progesterone concentration among the female participants on a regular diet (P > 0.05), regardless of equol phenotype.
Conclusion: The result suggests that exposure of isoflavone is correlated with the testosterone in healthy men under the usually lifestyle, and may be related to equol phenotype.