title: The effect of a lactose-restricted diet in patients with a positive lactose tolerance test, earlier diagnosed as irritable bowel syndrome: a 5-year follow-up study.
abstract: METHODS
  Prospectively, the effect of a lactose-restricted diet was evaluated among irritable bowel syndrome patients with lactose malabsorption. Lactose malabsorption was defined by a positive hydrogen breath test and a positive blood-glucose test. An analysis of symptoms was completed before, during, 6 weeks after and 5 years after starting the diet. In addition, the number of visits made by the patients to the outpatient clinic was scored during 6 years.
  
  
  RESULTS
  In 17 out of 70 irritable bowel syndrome patients (24.3%), lactose malabsorption was detected. There was no difference in the symptom score between patients with a positive lactose tolerance test and patients with a negative lactose tolerance test. After 6 weeks of the lactose-restricted diet, symptoms were markedly improved in lactose malabsorption-positive patients (P < 0.001). After 5 years, one patient was lost for follow-up, and 14 out of the remaining 16 lactose malabsorption patients (87.5%) still had no complaints during the lactose-restricted diet. Two patients chose not to follow the diet continuously and accepted the discomfort caused by lactose intake. Only two out of 16 patients (12.5%) no longer experienced any benefit from lactose restriction. In the 5 years before their diagnosis of lactose malabsorption, these 16 patients visited the outpatient clinic a total of 192 times (mean 2.4 visits per year per person; range 1-7 visits). In the 5 years after diagnosis, they visited the outpatient clinic a total of 45 times (mean 0.6 visits per year per person; range 0-6 visits; P < 0.0001).
  
  
  CONCLUSIONS
  In a large majority of irritable bowel syndrome patients with lactose malabsorption, which was previously clinically unrecognized, a lactose-restricted diet improved symptoms markedly both in the short term and the long term. Furthermore, visits by all patients to the outpatient clinic were reduced by 75%. We conclude that diet therapy is extremely cost- and time-saving. Therefore, it is strongly recommended that lactose malabsorption, which is easily treatable, is excluded before diagnosing irritable bowel syndrome.
authors.affiliation: Department of Gastroenterology, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands. CJM.Bohmer@azvu.nl
authors.forename: C J
authors.initials: CJ
authors.lastname: Böhmer
authors.forename: H A
authors.initials: HA
authors.lastname: Tuynman
mesh_terms: D000293:Adolescent; D000328:Adult; D000554:Ambulatory Care Facilities / Q000706:statistics & numerical data; D003109:Colonic Diseases, Functional / Q000175:diagnosis*; D003951:Diagnostic Errors; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007785:Lactose / Q000008:administration & dosage*; D007787:Lactose Intolerance / Q000175:diagnosis / Q000178:diet therapy*; D007789:Lactose Tolerance Test; D008297:Male; D008875:Middle Aged
chemical_list: D004040:Dietary Carbohydrates; D007785:Lactose