The etiology of irritable bowel syndrome (IBS) has not been fully defined, and the effects of probiotics on this gastrointestinal (GI) motility disorder remain unclear. Kajsa Kajander, MSc, and colleagues conducted a randomized, double-blind, placebo-controlled trial to investigate the effects of a probiotic mixture containing Lactobacillus rhamnosus GG, L rhamnosus LC705, Bifidobacterium breve Bb99, and Propionibacterium freudenreichii subsp shermanii JS on IBS symptoms.

Patients meeting Rome I or Rome II criteria for IBS (n = 103) were treated with a probiotic capsule or a placebo daily for 6 months. GI symptoms and bowel habits were recorded.

At the end of the study, the median reduction in symptom score (abdominal pain + distension + flatulence + borborygmi) was 42% in the probiotic group, compared with 6% in the placebo group (P = .015). For individual symptoms, borborygmi was milder in the probiotic group (P = .008), but no significant trends were observed for other individual symptoms. These results suggested that this probiotic mixture is effective in alleviating symptoms associated with IBS (Alimentary Pharmacology and Therapeutics, September 2005).