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Diamine Oxidase Testing: Regaining Optimal Health through Targeted DAO Testing and Treatment

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Maximizing the Benefits of DAO Testing: Tips for Optimal Health and Wellness

Have you ever felt like certain foods just don’t agree with you? Maybe you experience digestive issues, hives, or mood changes after eating certain foods like aged cheeses, processed meats, or alcohol. If so, you could be dealing with histamine intolerance, an inability to properly break down high-histamine foodsOne way to confirm a histamine intolerance is through a Diamine Oxidase (DAO) test

Importance of DAO enzyme testing

DAO is an enzyme we produce naturally to metabolize histamines in the foods we eat and the environment. Some people just don’t produce enough of this enzyme, resulting in excess histamines floating around that cause an immune response.

Relation to histamine intolerance and other health issues

DAO testing provides objective evidence of histamine intolerance that can guide an effective elimination diet and treatment plan.

Some people spend years cycling through diagnoses from GERD to IBS to food allergies,with no relief from debilitating symptoms like bloating, fatigue, and brain fog. Conventional medication was only providing short-term fixes, while the underlying issue remained. 

When they decided to get tested for low DAO, some of them were pleasantly shocked to see their levels drop significantly.

By understanding your DAO levels and learning which foods will affect you most, you can regain control of your health and experience greater vitality, focus and joy in life’s everyday moments once again. 

DAO testing should not be overlooked, as it holds promise for conditions beyond just histamine intolerance, including IBS, chronic fatigue, fibromyalgia, depression, and autism.

Types of Diamine Oxidase Tests

There are a few different ways to get tested for diamine oxidase or DAO, the enzyme responsible for breaking down histamines in the body. The most common approaches are a blood test to check DAO levels or a serum test to directly measure DAO activity.  Understanding the nuances between these tests proved key to getting an accurate diagnosis and targeted treatment plan.

Blood Test for Diamine Oxidase Levels

A simple blood test checks the amount of DAO enzyme in your bloodstream. If DAO levels are on the lower end of the range or undetectable, it likely indicates a deficiency that can lead to excess histamines causing issues like digestive upset, hives, or fatigue. While a low DAO blood level provides useful information, it does not directly measure how well your existing enzyme is actually working. 

Serum Test for Diamine Oxidase Activity

That’s where a DAO serum activity test comes in handy. This test analyzes a sample of your blood serum to determine how actively and efficiently your DAO enzyme is breaking down histamines. 

Some people may have normal or even high DAO levels in their blood but impaired enzyme activity, limiting their ability to properly metabolize histamines. This test can detect such enzymatic dysfunction, enabling a targeted treatment like DAO enzyme supplements, diet adjustments or other interventions to boost activity

For some, both a blood test and activity test may reveal dangerously low DAO, confirming histamine intolerance as the culprit behind chronic symptoms. Other people may need one, the other, or both tests to get an accurate assessment. The key is finding a doctor experienced with advanced testing for conditions like histamine intolerance, as limited understanding can lead to missed or misdiagnoses

Identifying Symptoms of DAO Deficiency

Some signs of possible DAO deficiency to be aware of include: digestive upset from foods high in histamines like aged cheeses, processed meats, and alcohol; chronic fatigue; hives or rashes; mood changes; and issues like IBS, depression, anxiety or fibromyalgia with no clear cause.  If several of these resonate with you, it’s a good idea to be tested for low DAO.

Finding a Medical Professional for Proper Diagnosis

The best way to get diagnosed is by finding an integrative or functional medicine doctor who is experienced with DAO testing and deficiency. They can order the necessary blood and serum tests, check DAO enzyme levels as well as activity, and evaluate other metabolic markers that can provide clues.

Schedule a DAO Test at SeeBeyond Medicine or request for a free consultation to learn more.

For some, significantly low DAO levels and impaired activity can lead to prescription of DAO enzymes, an elimination diet, and other evidence-based treatments to support health optimally.  

Others might opt for dietary changes and probiotics alone to do the trick. The treatment approach should be customized based on the severity of deficiency and underlying symptoms.

Labs That Offer Diamine Oxidase Testing

allergy testing

DAO deficiency is often overlooked but treatable. The most important first step is simply getting tested to determine if there is, in fact, an issue that needs correction. Within days or weeks of addressing the underlying insufficiency, many experience relief from debilitating symptoms and begin to regain vitality and joy.  Some continue periodic testing to ensure DAO levels and activity stay on track, adjusting treatment as needed to achieve and maintain optimal health.

Understanding Diamine Oxidase (DAO) Test Results

Receiving unexpected health test results can be stressful and confusing. When a person sees they’re borderline high, normal and low diamine oxidase or DAO levels across multiple tests, they’ll likely have many questions about what the results really meant and next steps.

What Do the Test Results Mean?

DAO is the enzyme responsible for breaking down histamines from foods and the environment that can lead to issues like digestive upset, hives, fatigue and brain fog when levels are impaired.  Seeing a mix of mildly high, normal and low DAO serum levels and activity meant there was likely some enzyme dysfunction impacting my ability to properly metabolize histamines, contributing to symptoms, but the deficiency was not severely limiting like in more extreme low DAO cases.

Evaluating Dao Enzyme Levels in Relation to Histamine Intolerance 

DAO testing and levels are not standardized or well understood, so results can be tricky to interpret.  The most important thing is evaluating your levels and activity in relation to your own symptoms and history. 

For example, if you frequently experience histamine reactions to foods but DAO tests come back in the normal range, there may still be impairments impacting you.  Similarly, slightly high DAO does not necessarily mean excess histamines are not an issue and symptoms will resolve on their own. 

Availability of Diamine Oxidase Tests in the US

At this point, DAO testing options in the US are limited.  Some integrative medicine doctors and functional medicine labs offer DAO testing, including serum levels and activity analysis. SeeBeyond Medicine can assist with DAO testing along with guidance on interpreting results

DAO test results should be evaluated along with a complete health history and symptoms to determine appropriate next steps. This may include dietary changes, such as an elimination diet; DAO supplements or enzymes; probiotics to support enzyme production; or other treatments to help boost DAO activity and relieve symptoms.  In some cases, periodic re-testing of DAO levels and activity can also be useful to ensure improvement and guide ongoing management.

Next Steps After Diamine Oxidase Testing

Some key next steps after DAO testing include:

Evaluating the underlying causes of low or impaired DAO. This could be an underlying condition like small intestine bacterial overgrowth (SIBO), candida, or leaky gut; poor diet low in nutrients needed for enzyme production; or another issue.  Treatment of the root cause will help ensure DAO levels and activity remain optimal. 

DAO enzyme supplements. Taking supplemental DAO enzymes is often recommended to help boost levels and activity, at least initially.  The dosage needs to be monitored under doctor guidance to avoid excessively high DAO activity. 

Dietary changes.  Following an elimination diet removing common histamine triggers like aged cheeses, processed meats, alcohol, and high-histamine grains/legumes can help reduce inflammation and support DAO production.  Probiotics also help maintain gut health and digestive enzyme function

Lifestyle optimization.  Other important lifestyle factors include managing stress, getting high-quality sleep, staying hydrated, limiting exposure to toxins, and avoiding smoking.  These basic self-care practices provide the foundation for health and wellness.

Monitor DAO levels and activity.  Some require periodic re-testing of DAO serum activity and/or levels to ensure sufficient improvement and guide continued management.  Levels should be re-checked under a doctor’s recommendation before adjusting or stopping treatment. 

Additional supplements.  For some, other supplements like digestive enzymes, glutathione, NAC or zinc may provide extra support for enzyme production and activity.  But supplements should always be used under the guidance of your doctor. 

Seeking medical care.  If symptoms do not start to noticeably improve with initial management steps within a few weeks, or DAO test results do not show a positive trend, it is best to follow up with your doctor.  Adjustments may need to be made to the treatment plan based on your specific situation and health needs. 

Treatment Options and Lifestyle Changes To Improve DAO Levels

DAO deficiency is often a sign of an underlying condition impacting health.  With the proper diagnosis, treatment and lifestyle changes, many are able to restore DAO functionality, relieve frustration symptoms, and profoundly improve vitality and quality of life. 

The key is committing to the recommended steps for management and not getting discouraged easily.  Most importantly, continue to work closely with your doctor to ensure you are on the best path forward based on your unique condition and needs.  Staying persistent yet patient will lead to healing.


Here are some common questions about Diamine Oxidase (DAO) testing and the answers:

What is Diamine Oxidase Testing?

Diamond Oxidase or DAO is the enzyme responsible for breaking down excess histamines in the body.  DAO testing analyzes your DAO levels and activity to determine if there is deficiency or impairment impacting your ability to properly metabolize histamines. This can lead to issues like digestive distress, hives, fatigue and mood changes in those with low DAO. 

How Can I Get Tested for Low DAO?

You can get tested for DAO deficiency through an integrative or functional medicine doctor like SeeBeyond Medicine.  They can order blood tests to check your DAO enzyme levels as well as a DAO serum activity test to analyze how efficiently your existing enzyme is breaking down histamines.

Can You Test for Diamine Oxidase at Home?

At-home DAO testing options are limited but available.  DAO testing kits for self-use at home along with guidance on interpreting results under medical supervision. However, at-home testing may not provide quite as comprehensive of an evaluation as testing through a doctor. Either way, any DAO results should be reviewed with your doctor to determine appropriate treatment based on your unique situation and needs. 

Other common questions and answers about DAO testing include:

How Accurate and Reliable Is the Test?

Like any lab test, DAO testing provides an objective measure but should be evaluated based on your complete health history and symptoms.  Results may be imprecise or difficult to interpret, in which case re-testing is often recommended under doctor supervision.

Is DAO Testing Covered by Insurance?

DAO testing is typically considered an investigational procedure and not covered by most insurance plans.  Costs range from $200 to $500 depending on the tests ordered.  However, some functional and integrative doctors may be able to obtain insurance approval on a case-by-case basis, especially if DAO deficiency is suspected to be contributing to another covered condition.

How Often Should I Retest My DAO Levels?

For some, periodic re-testing of DAO serum activity and/or levels is recommended to ensure good response to treatment and continued management, at least for a period of time.  However, re-testing should always be done under the guidance of your doctor based on your specific situation and needs.  Not all cases of low DAO require life-long monitoring but checking in periodically can provide reassurance and allow for adjustments as needed.

What Can I Do if I Have a DAO Deficiency?

Treatment options for improving DAO levels and activity include DAO supplements, diet changes like an elimination diet and probiotics, stress/lifestyle management, and addressing any underlying issues.  Additional supplements or medication may also be recommended under medical supervision based on severity of deficiency and symptoms.  The treatment plan should be customized to meet your unique health needs.

Schedule a Consultation to Explore DAO Testing and Treatment Options

DAO deficiency contributes to debilitating symptoms like digestive distress, fatigue, hives and mood changes by allowing excess histamines to build up in the body.  Many struggle for years with a mix of diagnoses, medication and dietary changes that do little to truly address the underlying issue.  DAO testing can help determine if impaired enzyme activity is the root cause of persistent health concerns and obscure symptoms. 

SeeBeyond Medicine provides integrative medical care with a focus on diagnosing underlying health conditions, using advanced testing when needed to uncover the root causes of symptoms. 

Schedule a consultation to learn more about DAO testing options, determine if you may be a candidate, and discuss next steps toward healing and vitality.  Knowledge and hope are power – start with the testing and treatment that could change your life.

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