title: Perception of lactose intolerance in irritable bowel syndrome patients.
abstract: BACKGROUND
  The importance of lactose malabsorption in irritable bowel syndrome (IBS) is not well defined and these patients often complain of lactose intolerance. To objectively measure lactose malabsorption, a hydrogen breath test (HBT) can be performed, but a discrepancy emerges between the results of the HBT and the symptomatic response during the HBT.
  
  
  OBJECTIVE
  To determine in a group of IBS patients whether self-perceived lactose intolerance and the symptomatic response to lactose HBT were conditioned by other factors besides the presence of lactose malabsorption.
  
  
  METHODS
  Oral challenge to lactose (50 g) was tested in 51 IBS patients to assess HBT malabsorption and the symptomatic response to lactose intolerance was scored on a validated questionnaire. Allergological screening for common inhalants and food allergens (including cow's milk) was performed. The presence of psychological factors (e.g. anxiety, depression, fatigue) was evaluated using validated questionnaires.
  
  
  RESULTS
  A total of 21 out of 51 patients (41.1%) were self-perceived to be lactose intolerant, 24/51 (47%) had a positive HBT, and 14/51 (27.4%) presented with symptoms of lactose intolerance during HBT. The serological screening for inhalant and food allergens was positive in 6/21 (28.6%) and 4/21 (19%) of patients who self-perceived lactose intolerance and in 5/14 (37.5%) and 3/14 (21.4%) in intolerant patients symptomatic during HBT. Only 1/51 (1.9%) presented evidence of IgE-mediated hypersensitivity to cow's milk. Patients who experienced symptoms of lactose intolerance during HBT presented more severe IBS symptoms [326 (296-398) vs. 215 (126-295) P=0.05] and a higher score of anxiety, depression, and fatigue. Factors influencing the symptoms of lactose intolerance during HBT resulted in an increase in hydrogen produced and in the severity of IBS.
  
  
  CONCLUSIONS
  In a cohort of 51 IBS patients, the symptoms of lactose intolerance during HBT were influenced by the capacity to absorb lactose and the severity of IBS. Other factors, such as the psychological status or an adverse reaction to milk, merit consideration as potential cofactors involved in lactose perception and tolerance.
authors.affiliation: Departments of aGastroenterology bPublic Health cImmunology, CHU de Nice, Université de Nice Sophia-Antipolis, Nice, France dDigestive System Research Unit, Hospital Universitari Vall d'Hebron, Barcelona, Spain.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Dainese
authors.forename: Francesc
authors.initials: F
authors.lastname: Casellas
authors.forename: Eugènia
authors.initials: E
authors.lastname: Mariné-Barjoan
authors.forename: Mylène
authors.initials: M
authors.lastname: Vivinus-Nébot
authors.forename: Stéphane M
authors.initials: SM
authors.lastname: Schneider
authors.forename: Xavier
authors.initials: X
authors.lastname: Hébuterne
authors.forename: Thierry
authors.initials: T
authors.lastname: Piche
mesh_terms: D000328:Adult; D001944:Breath Tests; D005260:Female; D005512:Food Hypersensitivity / Q000175:diagnosis / Q000523:psychology; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007408:Intestinal Absorption; D043183:Irritable Bowel Syndrome / Q000175:diagnosis / Q000523:psychology*; D007785:Lactose / Q000378:metabolism; D007787:Lactose Intolerance / Q000175:diagnosis / Q000378:metabolism / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D010465:Perception; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D012649:Self Concept; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
chemical_list: D007785:Lactose