Randomised, clinical trial: Eight weeks of treatment with probiotic Bifidobacterium breve, Bif195 lowers fatigue scores in patients with diarrhoea-predominant irritable bowel syndrome

Background: Patients with irritable bowel syndrome experience abdominal pain and stool habit disturbances, and often also extraintestinal symptoms such as fatigue. The disorder is linked to gut dysbiosis, and manipulation of the microbiota is considered a possible focus of treatment strategies.Aim: We aim to investigate the effect of the probiotic strain Bifidobacterium breve, Bif195 (DSM 33360) (Bif195) on symptoms and gut microbiome composition in patients with diarrhoea-predominant irritable bowel syndrome.Methods: This was a randomised, double-blind, placebo-controlled study. Sixty-one patients with moderate to severe disease activity were allocated to eight weeks of treatment with either Bif195 or placebo (1:1) followed by eight weeks of follow-up. The primary outcome was improvement of symptoms measured by the validated questionnaire IBS-symptom severity scale. Secondary and explorative outcomes were the effects of Bif195 on intestinal symptoms, quality of life, fatigue, and the gut microbiota. Modulation of transepithelial electrical resistance (TEER) of Caco-2 cells by Bif195 was investigated in vitro as a model of barrier integrity.Results: Bif195 did not affect primary or secondary outcomes; however, we found that Bif195 lowered fatigue scores compared to placebo. The relative abundance of Bifidobacterium breve was increased in the Bif195 group after eight weeks of treatment and returned to baseline after eight weeks of follow-up. Bif195 significantly increased TEER readings in vitro indicating enhanced barrier integrity.Conclusions: Eight weeks of treatment with probiotic Bif195 did not change intestinal symptoms, but lowered fatigue scores compared to placebo and enhanced barrier integrity in vitro.Clinicaltrials.gov: NCT04808271