A double-blind, randomized, placebo-controlled study assessing the impact of probiotic supplementation on the symptoms of irritable bowel syndrome in females.

Background: A previous exploratory study demonstrated the ability of the Lab4 probiotic to alleviate the symptoms of IBS, and post hoc data analysis indicated greatest improvements in the female subgroup. The aim of this study is to confirm the impact of this multistrain probiotic on IBS symptom severity in females.

Methods: An 8-week, single-center, randomized, double-blinded, placebo-controlled, superiority study in 70 females with Rome IV-diagnosed irritable bowel syndrome (IBS) receiving the Lab4 probiotic (25 billion colony-forming units) daily or a matched placebo. Changes from baseline in the IBS-symptom severity score (IBS-SSS), daily bowel habits, anxiety, depression, IBS-related control, and avoidance behavior, executive function, and the fecal microbiota composition were assessed. The study was prospectively registered: ISRCTN 14866272 (registration date 20/07/22).

Key Results: At the end of the study, there were significant between-group reductions in IBS-SSS (-85.0, p < 0.0001), anxiety and depression scores (-1.9, p = 0.0002 and -2.4, p < 0.0001, respectively), and the IBS-related control and avoidance behavior score (-7.5, p = 0.0002), all favoring the probiotic group. A higher proportion of the participants in the probiotic group had normal stool form (p = 0.0106) and/or fewer defecations with loose stool form (p = 0.0311). There was little impact on the overall diversity of the fecal microbiota but there were significant differences in Roseburia, Holdemanella, Blautia, Agathobacter, Ruminococcus, Prevotella, Bacteroides, and Anaerostipes between the probiotic and placebo groups at the end of the study.

Conclusions & Inferences: Daily supplementation with this probiotic may represent an option to be considered in the management of IBS.