Modulation of the gut microbiota: a focus on treatments for irritable bowel syndrome

ABSTRACT

Irritable bowel syndrome (IBS), which is characterized by recurrent abdominal pain and disordered bowel habits, is one of the most common functional bowel disorders. IBS is a substantial burden on both patient health-related quality of life and healthcare costs. Several pathophysiologic mechanisms have been postulated for the occurrence of IBS, including altered gastrointestinal motility, visceral hypersensitivity, changes in gut permeability, immune activation, gut-brain dysregulation, central nervous system dysfunction, and changes in the gut microbiota. Of note, both qualitative and quantitative differences have been observed in the gut microbiota of a population with IBS versus a healthy population. Because of the substantial interest in the gut microbiota and its role as a therapeutic target in IBS, this article provides an overview of specific interventions with the potential to modulate the gut microbiota in IBS, including elimination diets, prebiotics, probiotics, synbiotics, and nonsystemic antibiotics. Although probiotics and synbiotics are generally well tolerated, differences in the composition and concentration of different bacterial species and inclusion or exclusion of prebiotic components varies widely across studies and has prevented strong recommendations on their use in IBS. For nonsystemic antibiotics, rifaximin is indicated in the United States for the treatment of IBS with diarrhea in adults and has been shown to be efficacious and well tolerated in well-designed clinical trials. Overall, more consistent evidence is needed regarding the efficacy and safety of elimination diets, prebiotics, probiotics, and synbiotics for the treatment of patients with IBS. Furthermore, additional well-designed studies are needed that examine alterations in the gut microbiota that occur with these interventions and their potential associations with clinical symptoms of IBS.

KEYWORDS:

• Antibiotic
• constipation
• diarrhea
• diet
• irritable bowel syndrome
• microbiota
• prebiotic
• probiotic
• rifaximin

Acknowledgments

Technical editorial assistance was provided, under the direction of the authors, by Sophie Bolick, PhD, Synchrony Medical Communications, LLC, West Chester, Pennsylvania, USA. Funding for this support was provided by Salix Pharmaceuticals, Bridgewater, NJ, USA.

Declaration of Interests

LA Harris reports serving as a consultant for Salix Pharmaceuticals, Ironwood Pharmaceuticals, Inc., Allergan plc, Synergy Pharmaceuticals Inc., Synthetic Biologics, Inc., IM HealthScience, QOL Pharmaceuticals, and Napo Pharmaceuticals; as well as performing research with Alvine Pharmaceuticals and Rhythm Pharmaceuticals, Inc. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Additional information

Funding

The authors did not receive any compensation for development of this manuscript. Salix Pharmaceuticals provided funding for editorial support. Salix, the study sponsor, did not actively contribute to the content or have a role in the decision to submit, but reviewed the article for scientific accuracy.