Background ProMetrioS is a randomized, blinded, placebo-controlled cross-over trial investigating the effect of a specific multispecies probiotic 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, particularly 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 a placebo for 8 weeks in two study phases, separated by a 8-week washout period. The gut microbiome is analyzed at four timepoints: start of thestudy, after phase 1, after the washout phase, and at the end of the study (after phase 2) amplicon sequencing. Quality of life related to endometriosis is assessed using validated questionnaires in the same four timepoints. Our primary endpoint is the favorable modulation of the gut microbiome, particularly with respect to 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 ClinicalTrials.gov (NCT06929364).
Kralj et al. (2026) studied this question.