title: Fructose intolerance: an under-recognized problem.
abstract: OBJECTIVE
  Although the role of lactose intolerance in the pathogenesis of abdominal symptoms is well known, the role of fructose intolerance is unclear. Our aims were 1) to examine the prevalence of fructose intolerance in patients with unexplained abdominal symptoms, and 2) to explore whether fructose concentration influences fructose breath test.
  
  
  METHODS
  Over 2 yr, patients with unexplained symptoms answered questionnaires and underwent fructose breath tests. Patients received 50 g fructose in 150 ml water (33% solution). Breath samples were collected for hydrogen and methane. In a second study, breath test was performed after giving either 10%, 20%, or 33% fructose solution. Data were analyzed retrospectively.
  
  
  RESULTS
  A total of 183 patients (50 male, 133 female) had breath tests, of whom 134 (73%) were positive. Among these, 119 (89%) had elevated H(2), and 15 (11%) had elevated CH(4) or both gases. Questionnaires showed that flatus (83%), pain (80%), bloating (78%), belching (70%), and altered bowel habit (65%) were the most common symptoms. Breath test reproduced symptoms in 101 patients (75%). In the second study, 14/36 (39%) tested positive with a 10% solution, 23/33 (70%) with a 20% solution, and 16/20 (80%) with a 33% solution (10% versus 20% or 33%, p < 0.01).
  
  
  CONCLUSIONS
  Fructose intolerance may cause unexplained GI symptoms. The higher yield of positive tests in our initial study may be due to referral bias or testing conditions; lower test dose produced a lower yield. Nonetheless, recognition and treatment of fructose intolerance may help many patients.
authors.affiliation: Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.
authors.forename: Young K
authors.initials: YK
authors.lastname: Choi
authors.forename: Fredrick C
authors.initials: FC
authors.lastname: Johlin
authors.forename: Robert W
authors.initials: RW
authors.lastname: Summers
authors.forename: Michelle
authors.initials: M
authors.lastname: Jackson
authors.forename: Satish S C
authors.initials: SS
authors.lastname: Rao
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001944:Breath Tests / Q000379:methods; D005260:Female; D005632:Fructose / Q000032:analysis; D005633:Fructose Intolerance / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D005767:Gastrointestinal Diseases / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D015995:Prevalence; D012189:Retrospective Studies; D011795:Surveys and Questionnaires
chemical_list: D005632:Fructose