title: Lactose malabsorption in a population with irritable bowel syndrome: prevalence and symptoms. A case-control study.
abstract: BACKGROUND
  Symptoms after intake of milk are common in persons with irritable bowel syndrome (IBS). The aims of this study were to compare the prevalence of lactose malabsorption (LM) and symptoms related to intake of milk and lactose in subjects with IBS with that of healthy volunteers, and to search for symptoms that are characteristic of LM.
  
  
  METHODS
  A case-control study in a Norwegian population was initiated. Subjects with IBS were asked for symptoms related to intake of milk and lactose, tested for LM, and compared with a group of healthy volunteers.
  
  
  RESULTS
  The study comprised a total of 187 persons (82 with IBS and 105 volunteers), females/males: 138/49, mean age 47 years. In subjects with IBS and in healthy volunteers, LM was present in 3/74 (4.1%) and 4/105 (3.8%), respectively (ns), milk-related symptoms in 32/79 (40%) and 13/105 (12%), respectively (P < 0.001) and symptoms after intake of lactose in 28/74 (38%) and 21/104 (20%), respectively (P=0.01). Borborygmi starting within 5 h after intake of lactose and lasting for more than 2 h indicated LM (OR 61 (95% CI: 8-475), P < 0.001).
  
  
  CONCLUSIONS
  IBS and LM are unrelated disorders in a Norwegian population. Milk-related symptoms and symptoms after intake of lactose are unreliable predictors for LM. Precise symptom-based criteria might enhance the diagnostic accuracy for LM.
authors.affiliation: Department of Medicine, Innlandet Hospital Health Authority, Gjøvik, Norway.
authors.forename: P G
authors.initials: PG
authors.lastname: Farup
authors.forename: K W
authors.initials: KW
authors.lastname: Monsbakken
authors.forename: P O
authors.initials: PO
authors.lastname: Vandvik
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003611:Dairy Products / Q000009:adverse effects; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000150:complications*; D007785:Lactose / Q000009:adverse effects; D007787:Lactose Intolerance / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D007789:Lactose Tolerance Test; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D011795:Surveys and Questionnaires
chemical_list: D007785:Lactose