DAO Screen

The CNS DAO Screen uses a dry blood spot method to detect the concentration of the DAO enzyme within the blood, which is responsible for breaking down histamine.

Histamine is a chemical that is released from mast cells during an allergic reaction, but it also occurs naturally in certain histamine-rich foods. Other foods, although low in histamine themselves, can also encourage the release of histamine within the body. 


Frequently Asked Questions

What is histamine intolerance (HIT)?
Histamine intolerance (HIT) is caused by the inability of the body to breakdown histamine efficiently.
What causes histamine intolerance?
Insufficient levels, or reduced activity of the enzymes diamine oxidase (DAO) or histamine N-methyltransferase (HNMT), enables both endogenous and exogenous sources of histamine to increase histamine levels within the body.
What are the symptoms of histamine intolerance?
• Runny nose • Sneezing, Asthma • Diarrhoea • Abdominal cramps • Dysmenorrhea • Fatigue • Flushing (face and chest) • Headaches • Hypotension (low blood pressure) • Itchiness
Why test for histamine intolerance?
Until recently, the conventional method for diagnosing HIT was to adopt a low-histamine diet for several weeks and then observe if symptoms improved. However, following a low histamine diet can be very restrictive, especially as it requires individuals to avoid healthy foods. Being able to test for histamine intolerance can provide assurance to clients that they are restricting the diet for good reason, whilst enabling them to look at which cofactors may be beneficial in their programme.
What should be considered before testing?
Unless it has been recommended by a GP or other professional, it is important that anti-histamine medication is stopped for at least 1 week before testing. Testing should also not be done if a person is following a low-histamine diet, fasting, or pregnant, as DAO levels increase during pregnancy.
How does the test work?
Utilising proven ELISA-based technology, the DAO Screen test offers a convenient and reliable method to detect circulatory levels of DAO in the bloodstream.
What will the test results tell me?
The results will give details of the level of DAO enzyme present within the blood. This figure is compared to the normal reference range for serum DAO concentration, making it possible to assess whether there is a deficiency in this enzyme and if HIT might play a role in symptoms.
What can be done if I have histamine intolerance?
If the test results indicate a low DAO concentration, under the guidance of a professional, it may be helpful to follow a histamine free diet. While it is now possible to supplement the DAO enzyme, this should not detract from finding ways to naturally reduce histamine. One such method includes supporting the synthesis of DAO by considering potential deficiencies in its co-factors: Vitamin B6 and copper. Vitamin C is also important as it helps to degrade histamine. If your practitioner feels it is necessary to increase the intake of foods and supplements, rich in these nutrients, it may help to increase DAO synthesis and support the degradation of histamine. In addition, balancing the bowel flora and supporting its integrity, will play a key role in any protocol. This would include observing for potential leaky gut and reduced digestive ability.
What are the sample requirements and test turn around?
The test is easy to perform and only requires a finger prick sample collected on as a Dried Blood Spot (DBS) sample. Everything required to perform the test is included in the kit sent and once your sample has been taken all you need to do is return it to the CNS laboratory in the prepaid envelope. To ensure your sample is not rejected please follow the instructions carefully and don’t press/scrape blood onto the collection card. At least 2 circles should be FULLY SATURATED and left to dry for 3+ hours (overnight is fine). To ensure a quick turnaround of results please send samples to the lab as soon as they have dried. A test report that details the DAO concentration detected in the blood sample will be available within 15 working days.