Histamine & DAO analysis – histamine intolerance: stool + dried blood

Diamine oxidase (DAO) is the main enzyme that breaks down histamine from food (PubMed 17490952). Here, its activity is measured in blood from a dried blood drop (dried blood spot), reported in HDU/ml.

In one study, people with suspected histamine intolerance had on average lower DAO activity in blood than healthy comparison subjects (PubMed 23579881). However, it has not been shown that the blood value reflects DAO activity in the gut (PubMed 33921522), and the German guideline considers measuring DAO in blood not conclusive for a diagnosis (PubMed 34651098). A low value is therefore an indication, not proof of histamine intolerance.

A value within the reference range suggests that the enzyme is sufficiently active in blood. It does not reliably rule out histamine intolerance, because blood and gut activity cannot be equated (PubMed 33921522). In a cohort study, people with low, intermediate and higher DAO values differed in symptoms and course; the authors call for further studies (PubMed 35406126).

Histamine comes from foods such as aged cheese, wine or fermented vegetables and is also produced in the gut by bacteria (PubMed 33921522). A raised value in stool shows that there is a lot of histamine in the gut. The value alone does not show where it comes from; measurement in stool has been little studied scientifically. The report states the laboratory's reference range in ng/ml.

Histamine intolerance is described as an imbalance between the amount of histamine and the ability to break it down (PubMed 17490952). The analysis therefore shows two sides side by side: the amount of histamine in the gut (stool) and the activity of the breakdown enzyme (blood). Even together, the two values do not replace a medical assessment; they are building blocks to be viewed together with your symptoms.

Histamine intolerance refers to more histamine accumulating than the body can break down; complaints resembling an allergic reaction can occur without the immune system being involved (PubMed 17490952). Reduced DAO activity in the gut is considered the main cause (PubMed 33921522).

The condition is controversial because symptoms in the same person differ after similar triggers (PubMed 34209583).

A review names diseases of the intestinal lining and certain medications as possible reasons for lower DAO activity in the gut (PubMed 33921522). Alcohol and medications that release histamine or block DAO can favour symptoms (PubMed 17490952). Genetic factors are also discussed (PubMed 38674909).

Do not stop prescribed medication on your own before the test; talk to your doctor.

DAO is usually measured in blood, here from dried blood. How meaningful this is, is assessed differently: individual studies consider the measurement a useful tool (PubMed 23579881), while the guideline of the German-speaking allergy societies considers it not conclusive (PubMed 34651098). A review describes the assessment of histamine intolerance as time-consuming and multidisciplinary (PubMed 34209583).

This analysis therefore measures values that can feed into an assessment. A diagnosis is made by a doctor.

Research describes very different complaints in histamine intolerance, often after histamine-rich meals or alcohol; the evidence varies in strength:

• Bloating, fullness, abdominal pain and diarrhoea: bloating was the most common symptom in an evaluation of people with low DAO and suspected histamine intolerance; observed in studies (PubMed 30836736).
• Skin complaints such as redness, itching and hives: more frequent with low DAO in a cohort study, often together with headache (PubMed 35406126).
• Headache: described in reviews (PubMed 17490952).
• Runny or blocked nose, asthma-like symptoms: described in reviews and studies (PubMed 23579881).
• Palpitations, heart rhythm disturbances and low blood pressure: described in reviews (PubMed 17490952).

The complaints are non-specific and can have many other causes, such as allergies. The German guideline points out that they often cannot be reproduced in provocation tests (PubMed 34651098).

These are associations from studies, not causes in an individual person. The test cannot explain symptoms and does not provide a diagnosis. Persistent symptoms should first be assessed by a doctor.

If you have difficulty breathing, swelling of the face, lips or tongue, circulatory problems or fainting after eating, call the emergency number 112 immediately. If you have blood in your stool or black stool, unintended weight loss, fever, diarrhoea at night, severe or new abdominal pain, persistent vomiting or difficulty swallowing, the first step is a doctor’s practice, not a self-test. The same applies to new palpitations or a racing heart.

Complaints after certain foods may be a food allergy; this belongs in an allergy assessment. A stool test does not replace bowel cancer screening.

This page does not give treatment advice. Whether a result means anything at all and which steps make sense depends on your whole situation: symptoms, previous findings, medication and diet. The German guideline warns against restricting the diet unnecessarily strictly for years and recommends a professionally supported, personal approach (PubMed 34651098).

What makes sense for you belongs in a conversation with the ORY expert team or with your doctor or naturopath, for example from the ORY expert network. The results consultation is included in the price.

Before the stool sample, avoid an unusually histamine-rich meal such as red wine, aged cheese or fermented foods. Do not collect during menstruation, with acute gastrointestinal complaints or a bleeding haemorrhoid. Certain medications can affect DAO or histamine; talk to your doctor before changing anything.

The stool must not come into contact with toilet water. Enter the date and time of collection on the request form; this is mandatory for both tests. For the dried blood, discard the first drop, massage rather than squeeze the finger and let the blood spot air-dry for 45–60 minutes, without a hairdryer and out of the sun. Send both samples on the same day and only from Monday to Thursday.

You start with the stool test: place the collection aid in the toilet, catch the stool, insert the dosing stick at three points, put it back into the tube once, close and shake. Then comes the dried blood: disinfect the fingertip and let it dry, prick with the lancet, discard the first drop and take up 50 µl with the pipette, which you apply to the centre of a field on the DrySpot card.

Both samples go into the prepaid shipping bag together with the request form.

The analysis usually takes 7–21 days from the time the sample arrives at the laboratory. You will be notified as soon as your report is ready. The results consultation with the ORY expert team is included in the price.

The histamine and DAO analysis costs €93 including VAT, shipping, return shipping within Germany and the results consultation.

Statutory health insurance in Germany does not usually cover laboratory analyses that you order yourself. With private insurance, reimbursement may be possible; the process is described under “Reimbursement by private insurance”.

The histamine and DAO analysis (€93) measures histamine in stool and DAO activity in dried blood. The histamine stool test (€55) measures only histamine in stool. The basic gut profile (€285) combines histamine with gut flora and the gut barrier. For milk or fruit sugar there are the lactose breath test and the fructose absorption analysis (€65 each).

Which test makes sense for you can be clarified in the free initial consultation.