Urinary phytoestrogen levels related to idiopathic male infertility in Chinese men

Abstract

Phytoestrogens (PEs) are naturally occurring chemical constituents of certain plants. The internal PE exposures, mainly from diet, vary among different populations and in different regions due to various eating habits. To investigate the potential relationship between urinary PE levels and idiopathic male infertility and semen quality in Chinese adult males, 608 idiopathic infertile men and 469 fertile controls were recruited by eligibility screening procedures. Individual exposure to PEs was measured using UPLC-MS/MS as spot urinary concentrations of 6 PEs (daidzein, DAI; equol, EQU; genistein, GEN; naringenin, NAR; coumestrol, COU; and secoisolariciresinol, SEC), which were adjusted with urinary creatinine (CR). Semen quality was assessed by sperm concentration, number per ejaculum and motility. We found that exposures to DAI, GEN and SEC were significantly associated with idiopathic male infertility (P-value for trend=0.036; 0.002; and 0.0001, respectively), while these exposures had stronger association with infertile subjects with at least one abnormal semen parameter than those with all normal semen parameters. Exposures to DAI, GEN and SEC were also related to idiopathic male infertility with abnormal sperm concentration, number per ejaculum and motility (P-value for trend<0.05), while these exposures had stronger association with the infertile men with abnormal sperm number per ejaculum. These findings provide the evidence that PE exposures are related to male reproductive function and raise a public health concern because that exposure to PEs is ubiquitous in China.

Keywords: BMI; CI; COU; CR; CV; DAI; EQU; Exposure; GEN; Human urine; LODs; Male infertility; NAR; ORs; PEs; Phytoestrogens; SEC; Semen quality; UPLC–MS/MS; WHO; World Health Organization; body mass index; coefficients of variation; confidence interval; coumestrol; creatinine; daidzein; equol; genistein; limits of detection; naringenin; odds ratios; phytoestrogens; secoisolariciresinol; ultra high performance liquid chromatography–tandem mass spectrometry.