April 22, 2017 10:00 pm

histamine intolerance, mast cell activation, low histamine diet, elimination diet, histamine intolerance threshold, Alison Vickery, Health, Australia

The new guidelines for how to diagnose histamine intolerance provide an overview of the challenges that researchers and patients share.

Firstly, researchers ask not whether histamine intolerance exists but what its root cause is. Specifically, they ask: Is it actually what we eat?

Next, they propose new guidelines to diagnose histamine intolerance and then managing it.

The following summarises their findings and recommendations.

Why It May Not Be Just About Food

Scientific studies directly linking the consumption of histamine-rich foods to adverse reactions are limited.

For example, a German study on children with chronic abdominal pain concluded that, although 50% responded to a low histamine diet, only one child responded to a histamine challenge.

Consequently, this suggests that a low histamine diet alone is insufficient to diagnose histamine intolerance.

Different mechanisms may be at play: one where ingested histamine is the root cause and another where histamine is more a symptom of another root cause.

Why It May Not Be Just About DAO Deficiency

No scientific studies directly link eating high-histamine foods to a histamine-degrading enzyme diamine oxidase (DAO) deficiency.

However, researchers found that taking the DAO enzymes reduced symptoms, even if histamine was not ingested. 

Additionally, some practitioners use high-dose DAO supplements (2 before, 2 during, and 2 after a meal) for mast cell activation disorder.

Furthermore, another study showed that the reduction in DAO activity in the gut of patients with food allergies was insignificant when diagnosing histamine intolerance.

Instead, the histamine N-methyl-transferase (HNMT) activity was reduced, in proportion to higher histamine levels in the gut, thought to be due to mast-cell release in the colon.

In conclusion, these findings raise unanswered questions about the importance of DAO and HNMT to diagnose histamine intolerance

Mast Cell Activation,

Why Current Tests Are Unreliable To Diagnose Histamine Intolerance

All current tests to diagnose histamine intolerance test levels at a single point in time.

They do not test for levels before and after eating high-histamine foods. Therefore, no test can confirm or deny a link between histamine intolerance and ingested food to diagnose histamine intolerance.

Moreover, the available tests have significant problems. Specifically:

  • Testing DAO in the blood is inconclusive because DAO levels are not concentrated in the bloodstream. Ideally, a test would show DAO enzyme levels in the intestine or colon, but no such test is readily available.

  • Additionally, testing histamine in stool is problematic because intestinal bacteria can produce large amounts of histamine, which does not reflect ingested histamine or enzyme levels.

  • Furthermore, testing histamine in blood does not correlate with histamine or histamine intolerance symptoms. Functional practitioners use this test more as a marker for the methylation of histamine.

  • Testing methyl-histamine in urine is also unreliable because the level depends on both histamine and the protein content of foods. HNMT levels rise on a high protein but low histamine diet.

  • Lastly, the histamine skin-prick test does not link to either enzymes or high histamine foods.

As a result, the researchers do not recommend any of the above tests to diagnose histamine intolerance.

Although the researchers do not address this, it should also be noted that genetic testing is not a reliable method of diagnosing histamine intolerance as it merely shows the possibility rather than the actual occurrence of an error.

From my perspective, this is why I use autonomic response testing to diagnose histamine intolerance. Indeed, autonomic response testing can tell precisely what is present in the whole body and what precisely will address any imbalances.

IBS, IBD, Megasporebiotic-histamine-intolerance-

What Are We Missing?

The issue is not whether certain individuals respond to a low histamine diet or DAO supplements. Instead, the issue is that, in most cases, these are not the root cause.

Rather, researchers suggest that “histamine intolerance is more likely a complex of symptoms that can be attributed to histamine only in individual cases,” rather than an isolated condition exclusively triggered by ingested histamine.

They further hypothesise that the ‘missing link’ may be related to internal environmental factors, specifically:

  • Small intestinal permeability
  • Intestinal disorders (especially inflammatory ones and, in my experience, small intestinal bacterial overgrowth)
  • Hormone status
  • The composition of intestinal flora (especially, in my experience, histamine or amine-secreting bacterial infections)
  • Food selection, meal composition, and the interval between meals
  • Alcohol, and
  • Certain medications.

From my perspective, in diagnosing histamine intolerance, the internal environment is of paramount importance, with stressors falling into four categories: electrical, emotional, toxins, and infections.

Recommended Guidelines To Diagnose Histamine Intolerance

Amidst all this uncertainty, the German recommendations suggest diagnosing histamine intolerance by doing a limited-time elimination diet followed by a histamine challenge.

Diagnosing Histamine Intolerance

Their experience shows that intolerances can slowly improve beyond the low histamine threshold. Indeed, this is also my clinical experience. 

Most histamine-sensitive people eventually tolerate any amount of low-histamine foods, one serving of moderate-histamine foods, or a tablespoon of high-histamine foods daily. However, very high-histamine foods are rarely tolerated, if at all.

Furthermore, with ART, certain very high histamine foods confirm a diagnosis of histamine intolerance and indicate the likely thresshold. 

Importantly, when low histamine foods are not tolerated, it is essential to consider another diagnosis. 

Dietary Recommendations: The Three-Step Approach

To diagnose histamine intolerance, it is recommendationded to follow an elimination diet for the two-week test period only. Then, gradually reintroduce foods as follows:

Histamine Intolerance Guidelines

The researchers’ experience shows that tolerances increase beyond the strictly low histamine threshold.

Similarly, this aligns with my experience. Most histamine-sensitive people eventually tolerate any amount of low-histamine foods, one serving of moderate-histamine foods, or a tablespoon of high-histamine foods daily. However, very high-histamine foods are rarely tolerated, if at all.

Therefore, when low histamine foods are not tolerated, it is important to consider other or additional root causes, and not diagnose histamine intolerance.

Histamine Intolerance Food Lists To Diagnose Histamine Intolerance

Relying on the histamine intolerance food list to diagnose histamine intolerance is problematic.

The authors acknowledge the main problem with the lists is the histamine content of foods varies widely depending on storage, transportation, and processing.

Nevertheless, provided these safe food-handling practices are utilised, food lists can provide a structured way to diagnose histamine intolerance and identify histamine thressholds.

How to Use Antihistamines To Relieve Symptoms

Finally, once the practitioners diagnose histamine intolerance, the researchers recommend using H1 antihistamines for flushing and H2 blockers for nausea and vomiting during acute episodes only. Some practitioners use both together for an enhanced effect.


I would like to conclude with a few comments on how to diagnose histamine intolerance based on my clinical experience.

Around 70% of my clients in my practice trace their histamine intolerance to a gastrointestinal issue. Once treated, their histamine intolerance reverses.

Furthermore, I fully agree with the authors’ view that the missing link could be internal environmental factors.

However, I slightly disagree with the diagnostic guidelines that suggest exploring gastrointestinal issues only if the histamine challenge has failed.

For this reason, if you can afford to run only one test, please consider running a comprehensive gut test.

Additionally, in my experience, most gut tests only detect a portion of what is happening. Indeed, this is why I use autonomic response testing. 

Finally, many clients who come to me believing they need to follow a low-histamine diet do not have histamine intolerance but rather a different issue altogether. Working with a practitioner with clinical experience to diagnose histamine intolerance is imperative.

In conclusion, the authors have identified several areas that need research. In the meantime, we rely heavily on clinical experience to diagnose histamine intolerance.


Reese, Imke et al. “German guideline for the management of adverse reactions to ingested histamine.” Allergo Journal International 26.2 (2017): 72-79.

Hoffmann KM, Gruber E, Deutschmann A, Jahnel J, Hauer AC. Histamine intolerance in children with chronic abdominal pain. Arch Dis Child. 2013;98:832–833.

Komericki P, Klein G, Reider N, Hawranek T, Strimitzer T, Lang R, et al. Histamine intolerance: lack of reproducibility of single symptoms by oral provocation with histamine: a randomized, double-blind, placebo-controlled crossover study. Wien Klin Wochenschr. 2011;123:15–20.

Kuefner MA, Schwelberger HG, Weidenhiller M, Hahn EG, Raithel M. Both catabolic pathways of histamine via histamine-N-methyltransferase and diamine oxidase are diminished in the colonic mucosa of patients with food allergy. InflammRes. 2004;53(Suppl 1):S31–S32.

Töndury B, Wüthrich B, Schmid-Grendelmeier P, Seifert B, Ballmer-Weber B. Histaminintoleranz: Wie sinnvollist die Bestimmung der Diaminoxidase-Aktivität im Serum in der alltäglichen klinischen Praxis? Allergologie. 2008;31:350–6.

Kofler H, Aberer W, Deibl M, Hawranek TH, Klein G, Reider N, Fellner N. Diamine oxidase (DAO) serum activity: not a useful marker for diagnosis of histamine intolerance. Allergologie. 2009;32:105–9.

Schwelberger HG, Feurle J, Houen G. New tools for studying old questions: antibodies for human diamine oxidase. J Neural Transm (Vienna). 2013;120:1019–26. 10.

Jarisch R. Leserbrief. Allergologie. 2009;32:41–2.

Giera B, Straube S, Konturek P, Hahn EG, Raithel M. Plasma histamine levels and symptoms in a double blind placebo controlled histamine provocation. Inflamm Res. 2008;57(Suppl 1):S73–S74.

Keyzer JJ, Breukelman H, Wolthers BG, van den Heuvel M, Kromme N, Berg WC. Urinary excretion of histamine and some of its metabolites in man: influence of the diet. Agents Actions. 1984;15:189–94.

Häberle M. Biogene Amine – Klinische und lebens mittel chemische Aspekte. Zentralbl Haut. 1987;153:157–168.