Histamine-reduced diet and increase of serum diamine oxidase correlating to diet compliance in histamine intolerance.

Diagnosis of histamine intolerance (HIT) has been based on low serum diamine oxidase (DAO) values, functional gastrointestinal disorders and improvement of symptoms with a histamine-reduced diet (HRD). In a retrospective analysis of outpatients' charts we identified 101 patients with HIT. After a median of 13 months, a questionnaire was distributed to the patients so that they could be classified into four diet-compliance groups. Calculated with all 101 patients we found an increase of serum DAO values due to a HRD. In the 63 patients that completed the questionnaire, we found that 50 patients had improvement of symptoms or no continuing symptoms. A significant increase of serum DAO levels was found in the patients with strict and occasional diet compliance. Therefore, we demonstrate that a HRD is not only improving symptoms in HIT, but is causing an increase in serum DAO values that correlates with the degree of diet compliance.