Assessing the Effect of Probiotics in the Steroidal Module of the Athlete's Biological Passport

Athletes are increasingly using probiotic supplementation to support their overall health, and it can be particularly beneficial for female athletes in managing recurrent urinary tract infections and bacterial vaginosis. One route of probiotic administration for females is vaginal application, which enables direct modulation of the microbiota. While probiotics are widely recognised for their health benefits, their potential impact on urinary steroidal markers monitored in the Steroidal Module of the Athlete Biological Passport remains unexplored. Given the biological overlap between vaginal and urinary microbiomes, bacteria from vaginal probiotics could transfer into urine samples, potentially altering steroid profiles through microbial enzymatic activity. This study investigates whether vaginal probiotic use, specifically Lactobacillus reuteri and plantaraium, could influence urinary steroid markers relevant to the steroidal passport. In vitro and in vivo approaches were employed to evaluate the potential effects of contamination and variability on key steroidal markers. Analyses of in vitro and in vivo experiments suggest that vaginal probiotics do not substantially affect urinary steroid markers monitored in the Athlete Biological Passport. However, some variations were observed that merit further investigation. These findings contribute to a better understanding of how vaginal probiotics might interfere with doping control results, emphasising the need for further research to ensure accurate interpretation of urine steroidal profiles in the female athlete.