Probiotics, Prebiotics, and Synbiotics for Irritable Bowel Syndrome

Some patients with irritable bowel syndrome (IBS) use probiotic therapy — ingestion of live or attenuated microorganisms — either on their own or as recommended by clinicians. Alternatives to probiotics include prebiotics (nondigestible food ingredients that stimulate growth or activity of intestinal bacteria) and synbiotics (combinations of prebiotics and probiotics). In this meta-analysis, researchers examined the efficacy of these substances in patients with IBS or chronic idiopathic constipation.

For IBS, the proportion of patients with overall improvement in symptoms was significantly higher with probiotics than with placebo (44% vs. 27%) in 23 trials; seven patients had to be treated to benefit one patient. Synbiotics (2 trials) were o…