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Bloating and Distention in Irritable Bowel Syndrome: The Role of Gas Production and Visceral Sensation After Lactose Ingestion in a Population With Lactase Deficiency

Zhu, Yujin, MD1; Zheng, Xia, MD1; Cong, Yanqun, MD, PhD1; Chu, Hua, RN1; Fried, Michael, MD2, 3; Dai, Ning, MD1; Fox, Mark, MD2, 3, 4

American Journal of Gastroenterology: September 2013 - Volume 108 - Issue 9 - p 1516–1525
doi: 10.1038/ajg.2013.198
Functional GI Disorders

OBJECTIVES: Bloating and distention are often attributed to dietary factors by patients with irritable bowel syndrome (IBS). This study examined the effects of gas production and visceral hypersensitivity on digestive symptoms after lactose ingestion in a population with lactase deficiency.

METHODS: IBS patients (n=277) and healthy controls (HCs,n=64) underwent a 20-g lactose hydrogen breath test (LHBT) with evaluation of hydrogen gas production and lactose intolerance (LI) symptoms. Abdominal distention (199 IBS, 40 HCs) was measured during LHBT. Rectal sensitivity (74 IBS, 64 HCs) was assessed by barostat studies.

RESULTS: Hydrogen production and distention were similar in IBS patients and HCs during LHBT; however, LI was more frequent in IBS (53.8 vs. 28.1%,P<0.001), especially bloating (39.0% vs. 14.1%,P<0.001) and borborygmi (39.0 vs. 21.9%,P=0.010). Only 59.0% of patients with bloating had distention. No correlation was observed between girth increment and bloating (P=0.585). IBS patients had lower rectal sensory thresholds (P=0.001). Multivariate analysis indicated that hydrogen production increased bloating (odds ratio (OR) 2.19, 95% confidence interval (CI) 1.09–4.39,P=0.028) and borborygmi (OR 12.37, 95% CI 3.34–45.83,P<0.001) but not distention (P=0.673). Visceral hypersensitivity was associated with bloating (OR 6.61, 95% CI 1.75–25.00,P=0.005) and total symptom score (OR 3.78, 95% CI 1.30–10.99,P=0.014).

CONCLUSIONS: Gas production and visceral hypersensitivity both contribute to digestive symptoms, especially bloating and borborygmi, in IBS patients after lactose ingestion. Objective abdominal distention is not correlated with subjective bloating.

1 Department of Gastroenterology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China

2 Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland

3 Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland

4 Nottingham Digestive Diseases Center and Biomedical Research Unit, Queen's Medical Center, Nottingham, UK

Correspondence: Mark Fox, Department of Gastroenterology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, #3 East Qingchun Road, Hangzhou 310016, China. E-mail:

Correspondence: Mark Fox, Nottingham Digestive Diseases Centre and Biomedical Research Unit, Queen’s Medical Centre, Nottingham NG7 2UH, UK. E-mail:

Received 2 December 2012; accepted 1 June 2013

published online 6 August 2013

SUPPLEMENTARY MATERIAL is linked to the online version of the paper at

© The American College of Gastroenterology 2013. All Rights Reserved.
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