title: Subjective perception of lactose intolerance does not always indicate lactose malabsorption.
abstract: OBJECTIVE
  Symptomatic lactose intolerance is common; however, abdominal symptoms that patients experience after ingestion of lactose-containing foods can have causes beyond lactose malabsorption. We aimed to determine whether symptoms that patients usually attribute to lactose intolerance are comparable to symptoms provoked by a controlled lactose challenge and whether these symptoms are related to lactose absorption capacity.
  
  
  METHODS
  We performed an observational, prospective, transverse study of 353 patients referred for a lactose hydrogen breath test (HBT). Patients completed a validated questionnaire about symptoms associated with consumption of dairy products at home (home symptoms). After a 50-g lactose breath test, they completed the same questionnaire again (lactose challenge symptoms). Patients were assigned to groups of absorbers or malabsorbers according to HBT results and tolerants or intolerants according to the results of the questionnaire.
  
  
  RESULTS
  The total symptom score was significantly higher for home symptoms than for the lactose challenge (16 vs 8, P < .01). Symptoms perceived at home were reported to be more intense than those that followed the lactose challenge for lactose absorbers compared with malabsorbers (16 vs 4, P < .01) and lactose tolerants compared with intolerants (12 vs 2, P < .05). Overperception of lactose intolerance at home was similar in men and women.
  
  
  CONCLUSIONS
  Daily life symptoms that patients associate with lactose intolerance are often unrelated to lactose malabsorption. Even among true lactose malabsorbers, symptom recall tends to be amplified by the patient. Thus, conventional anamnesis is a highly unreliable tool to establish symptomatic lactose malabsorption.
authors.affiliation: Digestive System Research Unit, Hospital Universitari Vall d'Hebron, Barcelona, Spain. fcasellas@vhebron.net
authors.forename: Francesc
authors.initials: F
authors.lastname: Casellas
authors.forename: Anna
authors.initials: A
authors.lastname: Aparici
authors.forename: Maite
authors.initials: M
authors.lastname: Casaus
authors.forename: Purificación
authors.initials: P
authors.lastname: Rodríguez
authors.forename: Juan R
authors.initials: JR
authors.lastname: Malagelada
mesh_terms: D000328:Adult; D001944:Breath Tests; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007785:Lactose / Q000378:metabolism*; D007787:Lactose Intolerance / Q000175:diagnosis* / Q000473:pathology / Q000523:psychology*; D008297:Male; D010465:Perception; D011446:Prospective Studies; D011795:Surveys and Questionnaires
chemical_list: D007785:Lactose