The role of probiotics in the treatment of endometriosis (ProMetrioS): a randomised double-blinded placebo-controlled cross-over trial

Abstract Background ProMetrioS is a randomised blinded placebo-controlled cross-over trial investigating the effect of specific multispecies probiotics in patients with endometriosis. The aim of this clinical trial is to determine whether probiotic treatment can significantly modulate gut microbiome composition and functionality in endometriosis patients, specifically parameters associated with the estrobolome. Methods This is a double-blinded, randomized, cross-over, placebo-controlled trial. Participants are randomly allocated to receive either 3 g of a probiotic formulation daily or placebo for 8 weeks in two study phases, separated by a 8-week washout period between the two phases. The gut microbiome is analysed in four time-points: start-of-study, after phase 1, after the washout phase, end-of-study (after phase 2) via amplicon sequencing. Quality of life related to endometriosis is assessed via validated questionnaires in the same four time-points. Our primary endpoint is a favorable modulation of the gut microbiome, especially in prospect of the estrobolome. Secondary endpoints include changes in quality of life, reported symptomatology and psychophysical condition. Discussion: The findings of this study will provide the first evidence for the use of a combination of probiotics in the treatment of endometriosis. The results are expected at the end of 2025. Trial registration: pending