Effects of butylated hydroxytoluene (BHT) metabolites on sperm quality in adult males: a cross-sectional study

Purpose To investigate the associations between urinary concentrations of BHT and its metabolites and sperm quality parameters in adult males. Materials and Methods A total of 282 adult males seeking fertility care were enrolled. Urinary concentrations of BHT metabolites (BHA, BHT-CHO, BHT-COOH, BHT-OH, BHT-Q, and BHT-quinol) were measured by HPLC MS/MS. Sperm quality parameters included sperm count, sperm concentration, progressive motility, normal morphology rate, and DNA fragmentation index (DFI). Multiple linear regression and Bayesian kernel machine regression (BKMR) were used to evaluate individual and joint associations, adjusting for age, BMI, household income, and smoking status. Results In multiple linear regression, higher tertiles of urinary BHA were significantly positively associated with higher sperm concentration ( P for trend < 0.05). Similarly, higher tertiles of BHT-COOH were significantly positively correlated with more total sperm count ( P for trend < 0.05). Higher tertiles of BHT-OH, BHT-Q, and BHT- quinol were significantly positively associated with normal sperm morphology rate (all P for trend < 0.05). BKMR model did not reveal a monotonic overall joint effect of the metabolite mixture on total sperm count, sperm concentration, or normal morphology rate, but individual metabolite trends were consistent with the linear regression results. Conclusions The overall elevated concentrations of BHT and its metabolites showed no significant correlation with sperm quality, while increased levels of certain metabolites were positively associated with improved sperm quality. Further in-depth investigations are still required to systematically clarify the effects of BHT on sperm quality, so as to provide solid scientific evidence for the comprehensive improvement of male reproductive health.