OBJECTIVES: The term histamine intolerance stands for a range of symptoms
involving various effector organs after the consumption of histamine-rich food.
Our intention was to objectify and quantify histamine-associated symptoms and to 
analyse whether oral administration of the histamine-degrading enzyme diamine
oxidase (DAO) caused a reduction of symptoms.
PATIENTS AND METHODS: Four Austrian
centres participated. Patients suspected to be histamine intolerant were
recruited. The first step consisted in the open oral provocation of these
patients with 75 mg of liquid histamine. Patients who developed symptoms were
tested in a randomised double blind crossover provocation protocol using
histamine-containing and histamine-free tea in combination with DAO capsules or
placebo. Main and secondary symptoms (strongest and weaker symptoms based on a
ten-point scale) were defined, the grand total of all symptoms of the individual 
provocation steps was determined and changes in symptoms after administration of 
DAO were measured.
RESULTS: Thirty nine patients reacted to the open histamine
provocation and were enrolled in the blinded part. Here, both the main and
secondary symptoms were not reproducible. Subjects reacted sometimes unexpectedly
and randomly. Regarding the total symptom scores, the differences between the
three treatment groups were statistically significant. The intake of DAO
demonstrated a statistically significant reduction of histamine-associated
symptoms compared to placebo (P = 0.014).
CONCLUSIONS: Oral provocation with 75
mg of liquid histamine failed to reproduce histamine-associated single symptoms
in many patients. One may suggest that histamine-intolerant subjects reacted with
different organs on different occasions. As a consequence, reproducibility of
single symptoms alone may not be appropriate to diagnose histamine-intolerance
whereas a global symptom score could be more appropriate. The fact, that the
intake of DAO capsules compared to placebo led to a statistically significant
reduction of total symptom scores, may indirectly point in the same direction.


Source: Wien Klin Wochenschr. 2010 Dec 20