Small Intestinal Bacterial Overgrowth: A Framework for Understanding Irritable Bowel Syndrome

Henry C. Lin, MD

JAMA. 2004;292:852-858.

Context Irritable bowel syndrome (IBS), which affects 11% to 14% of the population, is a puzzling condition with multiple models of pathophysiology including altered motility, visceral hypersensitivity, abnormal brain-gut interaction, autonomic dysfunction, and immune activation. Although no conceptual framework accounts for all the symptoms and observations in IBS, a unifying explanation may exist since 92% of these patients share the symptom of bloating regardless of their predominant complaint.

Evidence Acquisition Ovid MEDLINE was searched through May 2004 for relevant English-language articles beginning with those related to bloating, gas, and IBS. Bibliographies of pertinent articles and books were also scanned for additional suitable citations.

Evidence Synthesis The possibility that small intestinal bacterial overgrowth (SIBO) may explain bloating in IBS is supported by greater total hydrogen excretion after lactulose ingestion, a correlation between the pattern of bowel movement and the type of excreted gas, a prevalence of abnormal lactulose breath test in 84% of IBS patients, and a 75% improvement of IBS symptoms after eradication of SIBO. Altered gastrointestinal motility and sensation, changed activity of the central nervous system, and increased sympathetic drive and immune activation may be understood as consequences of the host response to SIBO.

Conclusions The gastrointestinal and immune effects of SIBO provide a possible unifying framework for understanding frequent observations in IBS, including postprandial bloating and distension, altered motility, visceral hypersensitivity, abnormal brain-gut interaction, autonomic dysfunction, and immune activation.

Author Affiliation: Division of Gastrointestinal and Liver Diseases, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles.

Gastroesophageal reflux symptoms in patients with celiac disease and the effects of a gluten-free diet.

Nachman F, Vázquez H, González A, Andrenacci P, Compagni L, Reyes H, Sugai E, Moreno ML, Smecuol E, Hwang HJ, Sánchez IP, Mauriño E, Bai JC.

Department of Medicine; Dr. C. Bonorino Udaondo Gastroenterology Hospital; Buenos Aires; Argentina.
Abstract

BACKGROUNDS & AIM:: Celiac disease (CD) patients often complain of symptoms consistent with gastroesophageal reflux disease (GERD). We aimed to assess the prevalence of GERD symptoms at diagnosis and to determine the impact of the gluten-free diet (GFD). METHODS:: We evaluated 133 adult CD patients at diagnosis and 70 healthy controls. Fifty-three patients completed questionnaires every three months during the first year and more than 4 years after diagnosis. GERD symptoms were evaluated using a sub-dimension of the Gastrointestinal Symptoms Rating Scale for heartburn and regurgitation domains. RESULTS:: At diagnosis, celiac patients had a significantly higher reflux symptom mean score than healthy controls (p <0.001). At baseline, 30.1% of CD patients had moderate to severe GERD (score >3) compared with 5.7% of controls (p <0.01). Moderate to severe symptoms were significantly associated with the classical clinical presentation of CD (35.0%) compared with atypical/silent cases (15.2%, p <0.03). A rapid improvement was evidenced at 3 months after initiate treatment with a GFD (p <0.0001) with reflux scores comparable to healthy controls from this time point onward. CONCLUSION:: GERD symptoms are common in classically symptomatic untreated CD patients. The GFD is associated with a rapid and persistent improvement in reflux symptoms that resembles the healthy population. Copyright © 2010 AGA Institute. Published by Elsevier Inc. All rights reserved. PMID: 20601132 [PubMed - as supplied by publisher]