Clinical Question: Can probiotic treatment decrease the symptoms of irritable bowel syndrome?

Bottom Line: The probiotic Bifidobacterium bifidum MIMBb75 is a normal gastrointestinal tract inhabitant (along with several hundred other commensal organisms). This strain, found in some probiotic formulations, decreases overall symptoms in patients with irritable bowel symptoms and is an inexpensive and safe alternative to medications. (Level of Evidence: 1b)

Reference: Guglielmetti S, Mora D, Gschwender M, Popp K. Randomised clinical trial: Bifidobacterium bifidum MIMBb75 significantly alleviates irritable bowel syndrome and improves quality of life -- a double-blind, placebo controlled study. Alimen Pharmacol Ther 2011;33(10):1123-1132.

Study Design: Randomized controlled trial (double-blinded)

Funding Source: Industry

Allocation: Uncertain

Setting: Outpatient (primary care)

Synopsis: The German investigators conducting this study recruited 132 adults with mild to moderate irritable bowel syndrome (IBS; Rome III criteria) to participate in the study. Placebo and control groups were well matched for IBS subtype, with 23% of control patients having the diarrhea-predominant type, 15% having the constipation-predominant type, and 62% having the alternating type. During the first 2 weeks patients did not receive any treatment but kept symptom diaries. Patients with at least 2 days of mild to moderate pain during the second week of the study (n = 122) were randomly assigned (allocation concealment not specified) to receive 4 weeks of treatment with placebo (maltodextrin, which uncommonly causes diarrhea) or B bifidum 1 billion units followed by 2 weeks of observation without treatment. The main outcome was a rating on a 7-point scale asking about symptoms in the past 24 hours. Scores at baseline were approximately 2.8 of a possible 6 in both groups (moderate symptoms). After treatment, these scores dropped by an average 0.88 in the treated group as compared with 0.16 in the placebo group (P < .0001). Differences in scores appeared in the first week of treatment and continued to be different throughout the treatment period. The percent of patients responding -- that is, experiencing an improvement of at least 1 point on the Likert scale in at least 2 of the 4 weeks -- was significantly higher in the treatment group (57% vs 21%; P = .0001). Scores were not significantly different in the 2 weeks after treatment was discontinued.