A randomized controlled trial of a probiotic, VSL#3, on gut transit and symptoms in diarrhoea‐predominant irritable bowel syndrome

Summary Aim : To investigate the effects of a probiotic formulation, VSL#3, on gastrointestinal transit and symptoms of patients with Rome II irritable bowel syndrome with predominant diarrhoea. Methods : Twenty‐five patients with diarrhoea‐predominant irritable bowel syndrome were randomly assigned to receive VSL#3 powder (450 billion lyophilized bacteria/day) or matching placebo twice daily for 8 weeks after a 2‐week run‐in period. Pre‐ and post‐treatment gastrointestinal transit measurements were performed in all patients. Patients recorded their bowel function and symptoms daily in a diary during the 10‐week study, which was powered to detect a 50% change in the primary colonic transit end‐point. Results : There were no significant differences in mean gastrointestinal transit measurements, bowel function scores or satisfactory global symptom relief between the two treatment groups, pre‐ or post‐therapy. Differences in abdominal bloating scores between treatments were borderline significant (P = 0.09, analysis of covariance). Further analysis revealed that abdominal bloating was reduced (P = 0.046) with VSL#3 [mean post‐ minus pre‐treatment score, − 13.7; 95% confidence interval (CI), − 2.5 to − 24.9], but not with placebo (P = 0.54) (mean post‐ minus pre‐treatment score, − 1.7; 95% CI, 7.1 to − 10.4). With the exception of changes in abdominal bloating, VSL#3 had no effect on other individual symptoms: abdominal pain, gas and urgency. All patients tolerated VSL#3 well. Conclusion : VSL#3 appears to be promising in the relief of abdominal bloating in patients with diarrhoea‐predominant irritable bowel syndrome. This is unrelated to an alteration in gastrointestinal or colonic transit.