title: Bloating and distention in irritable bowel syndrome: the role of gas production and visceral sensation after lactose ingestion in a population with lactase deficiency.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Gastroenterology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
authors.forename: Yujin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xia
authors.initials: X
authors.lastname: Zheng
authors.forename: Yanqun
authors.initials: Y
authors.lastname: Cong
authors.forename: Hua
authors.initials: H
authors.lastname: Chu
authors.forename: Michael
authors.initials: M
authors.lastname: Fried
authors.forename: Ning
authors.initials: N
authors.lastname: Dai
authors.forename: Mark
authors.initials: M
authors.lastname: Fox
mesh_terms: D000328:Adult; D002239:Carbohydrate Metabolism, Inborn Errors / Q000150:complications / Q000503:physiopathology*; D004108:Dilatation, Pathologic / Q000150:complications; D005260:Female; D005414:Flatulence / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000150:complications / Q000503:physiopathology*; D043322:Lactase / Q000172:deficiency; D007785:Lactose / Q000008:administration & dosage*; D007787:Lactose Intolerance / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation; D012684:Sensory Thresholds / Q000502:physiology; D059265:Visceral Pain / Q000150:complications / Q000503:physiopathology*
chemical_list: D043322:Lactase; D007785:Lactose