title: Serum diamine oxidase activity in patients with histamine intolerance.
abstract: BACKGROUND
  Intolerance to various foods, excluding bona fide coeliac disease and lactose intolerance, represents a growing cause of patient visits to allergy clinics.Histamine intolerance is a long-known, multifaceted clinical condition triggered by histamine-rich foods and alcohol and/or by drugs that liberate histamine or block diamine oxidase (DAO), the main enzyme involved in the metabolism of ingested histamine. Histamine limitation diets impose complex, non-standardized restrictions that may severely impact the quality of life of patients.
  
  
  METHODS
  We retrospectively evaluated 14 patients who visited allergy outpatient facilities in northern Italy with a negative diagnosis for IgE-mediated food hypersensitivity, coeliac disease, conditions related to gastric hypersecretion, and systemic nickel hypersensitivity, and who previously underwent a histamine limitation diet with benefits for their main symptoms. Serum diamine oxidase levels and the clinical response to diamine oxidase supplementation were investigated.
  
  
  RESULTS
  We found that 10 out of 14 patients had serum DAO activity<10 U/mL, which was the threshold suggested as a cutoff for probable histamine intolerance. Moreover, 13 out of 14 patients subjectively reported a benefit in at least one of the disturbances related to food intolerances following diamine oxidase supplementation. The mean value (±SD) of diamine oxidase activity in the cohort of patients with histamine intolerance symptoms was 7.04±6.90 U/mL compared to 39.50±18.16 U/mL in 34 healthy controls (P=0.0031).
  
  
  CONCLUSIONS
  In patients with symptoms triggered by histamine-rich food, measuring the serum diamine oxidase activity can help identify subjects who can benefit from a histamine limitation diet and/or diamine oxidase supplementation.Properly designed, controlled studies investigating histamine intolerance that include histamine provocation are indispensable for providing insights into the area of food intolerances, which are currently primarily managed with non-scientific approaches in Italy.
authors.affiliation: Allergy Outpatients Service, General Hospital, P. le Ospedale n. 1, 24047 Treviglio, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Manzotti
authors.affiliation: Laboratory of Cellular and Molecular Allergology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Breda
authors.affiliation: Department of Medicine and Science of Ageing, G. D'Annunzio University, Chieti, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Di Gioacchino
authors.affiliation: Laboratory of Cellular and Molecular Allergology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy Department of Medicine and Science of Ageing, G. D'Annunzio University, Chieti, Italy s.burastero@hsr.it.
authors.forename: S E
authors.initials: SE
authors.lastname: Burastero
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D006631:Amine Oxidase (Copper-Containing) / Q000097:blood*; D002648:Child; D005260:Female; D005512:Food Hypersensitivity / Q000201:enzymology / Q000209:etiology*; D006636:Histamine Release; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D006631:Amine Oxidase (Copper-Containing)
keywords: diamine oxidase; food intolerance; histamine intolerance; low histamine diet