Probiotics, Prebiotics, Synbiotics, and Other Strategies to Modulate the Gut Microbiota in Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is a common, sometimes disabling gastrointestinal disorder of varying phenotype and unknown etiology. As a valid biomarker for IBS is not available, diagnosis continues to rest on clinical grounds alone. A number of lines of evidence, some direct, some more indirect, implicate the gut microbiome in the initiation or perpetuation of symptoms or even in some instances, such as postinfectious IBS, in the basic pathogenesis of the disorder. A variety of therapeutic strategies could alter the microbiome in IBS and ameliorate symptoms: diet, probiotic, probiotics, and antibiotics. While a number of dietary interventions have been proposed and many, such as fiber supplementation or the elimination of fermentable carbohydrates, will undoubtedly impact on the microbiome, there is as yet little data on correlations between symptomatic response and changes in the microbiome. The same holds true for antibiotic therapy. Probiotics seem to benefit the irritable bowel sufferer, but an assessment of the role of probiotics in IBS is still hampered by a shortage of high-quality clinical trials.