Shop Featured Products (click to view) | FREE Domestic Shipping $100+

Free Consultation

Diamine Oxidase Activity: What You Need to Know

schedule your Consultation NOW
a woman is sneezing

Balancing Histamine Levels: Exploring the Critical Role of Diamine Oxidase Activity in Your Health

Wondering why that sneeze keeps coming back, even after taking over-the-counter antihistamines? The answer may lie within your body’s ability to break down histamine – specifically, your diamine oxidase (DAO) activity.

Diamine Oxidase Activity (DAO) and Its Role in Histamine Metabolism and Detoxification

As a key enzyme in histamine metabolism, DAO helps ensure your histamine levels remain in balance. Too much histamine circulating in the blood can lead to unpleasant symptoms like sneezing, runny nose, and hives. Not enough histamine and your allergy responses become dull and unresponsive. 

Importance of Maintaining Proper Histamine Levels in the Body

Proper DAO activity is essential for detoxifying excess histamine and maintaining healthy histamine levels throughout your body. When DAO is impaired, histamine builds up leading to inflammation and disruptive allergy reactions. 

So you can see, DAO deserves your attention and support. Keeping this enzyme working efficiently will help you stay comfortable and able to enjoy life to the fullest, without interference from bothersome allergies.

The Role of Diamine Oxidase in Histamine Degradation

As an enzyme found primarily in the small intestine, diamine oxidase plays a central role in degrading histamines before they enter the bloodstream. DAO converts histamines into innocuous byproducts that your body can easily eliminate

The intestinal mucosa houses billions of beneficial bacteria and contains high concentrations of DAO, perfectly positioned to break down histamines from the foods you eat. By the time histamines have been absorbed into the blood, DAO has already worked to neutralize most of them. Any remaining histamines are swiftly eliminated by the liver. 

This enzymatic process generates hydrogen peroxide as a byproduct, which helps maintain a healthy gut barrier and balanced microflora. Proper DAO activity, therefore, supports not only histamine homeostasis but also digestive health and immunity

When DAO is insufficient, excess histamines can leak into the circulation, causing inflammation and damage to blood vessels. This leads to a variety of issues like gastrointestinal distress, skin problems, headaches, and more. On the other hand, very high DAO activity may deplete histamines too quickly, impairing your body’s ability to respond to allergens or other threats. 

In summary, DAO fills an essential role in preserving eustasis by efficiently yet selectively breaking down histamines. It helps keep histamine levels optimized so you can enjoy your meals without discomfort. 

Histamine and Its Effects on Health

Histamine has a profound influence over your health and well-being. In optimal amounts, histamine helps maintain immune function, protects against infection, and promotes inflammation to heal wounds or fight foreign invaders.

Physiological Effects of Histamine on Immune Response and Inflammation

As part of your immune response, histamine triggers the release of antibodies and leukocytes to destroy pathogens. It widens blood vessels, increases blood flow to affected areas, and recruits additional immune cells to the site of injury or attack. This acute inflammatory response, while unpleasant, helps eliminate threats and restore homeostasis. 

However, too much histamine can have detrimental effects, especially if not properly degraded. Excess histamine in the gut leads to a condition known as histamine intolerance, characterized by symptoms like nausea, diarrhea, abdominal pain, headaches, hives, and fatigue. By disrupting digestion and absorption, high histamine intolerance compromises your quality of life and health over time. 

Difference Between Histamine Intolerance and Food Allergy

Histamine intolerance differs from a food allergy. With a food allergy, your immune system mistakenly identifies certain foods as dangerous, while histamine intolerance simply means you have difficulty breaking down the normal amounts of histamines in food. Food allergies tend to produce more severe, immune-mediated symptoms. Histamine intolerance causes inflammation and digestive issues due to the buildup of excess histamine.

Factors Influencing Diamine Oxidase Activity

Several factors can influence your diamine oxidase (DAO) activity and histamine metabolism. Genetics plays a significant role, as some people are born with certain DAO gene variants that make impaired enzymatic activity more likely. 

Diet and gut health also strongly impact DAO, as the small intestine is responsible for breaking down most dietary histamines. Underlying health conditions like celiac disease or Crohn’s disease may also contribute to changes in DAO activity and histamine intolerance symptoms.

DAO gene polymorphisms have been associated with decreased enzyme function, especially variants found in the rs10156191 single nucleotide polymorphism (SNP). People inheriting genetic variants that compromise DAO activity tend to be more susceptible to histamine buildup and symptoms of intolerance. 

How These Factors Can Lead to Changes in Serum Diamine Oxidase Activity Levels and Histamine Intolerance Symptoms

A diet low in nutrients that support DAO and high in histamine-containing foods can also strain DAO’s ability to degrade excess histamine. Things like lectins, preservatives, and aged proteins require more DAO activity to metabolize, potentially leading to decreased enzyme levels over time. Staying hydrated, increasing fiber intake, and eliminating Fast Foods/processed items may help boost DAO and relieve symptoms.

Underlying gastrointestinal inflammation or damage reduces surface area where DAO is produced, weakening histamine metabolism. Conditions like celiac disease, Crohn’s, ulcerative colitis, and Helicobacter pylori infection have been linked with low serum DAO levels and increased histamine intolerance. Treating underlying disease and supporting gut healing will help restore balance. 

To summarize, many interconnecting factors influence your diamine oxidase activity and ability to handle histamines comfortably. Genetics establishes a baseline, diet and gut health impact enzyme production, and underlying conditions can compromise DAO. By understanding how each factor affects you, you gain more control over managing symptoms like nausea, diarrhea, rashes, and headaches – and living life to the fullest without interference from excess histamine. 

Dietary Management of Histamine Intolerance

gut health

Strict diets that limit histamine-rich foods can be very effective for managing histamine intolerance symptoms. Known as low-histamine or histamine-free diets, these eating plans focus on avoiding foods high in histamines while consuming plenty of histamine-safe options.

The primary benefit of following a histamine diet is reduced inflammation and improved digestion. By limiting major histamine triggers like aged cheeses, fermented foods, dried fruits, nuts, and pickled vegetables, a histamine diet helps minimize excess histamine intake that can overwhelm your body’s ability to break it down. This leads to less bloating, cramping, rashes and other unpleasant symptoms. 

Challenges of a histamine dietDescription
Difficulty finding alternativesHistamine diets can be quite restrictive, requiring extra effort to find histamine-safe alternatives and to meet nutritional needs.
Individual food sensitivitiesWhile certain foods are high in histamines, some people may tolerate them just fine. An elimination diet can help determine personal triggers.
Lack of probiotic benefitFermented foods contain good bacteria, so histamine diets may compromise gut health if followed for extended periods. Occasional inclusion of fermented foods is reasonable.
Increased gut permeabilitySome evidence shows that limiting certain food groups like FODMAPs can increase gut permeability, aggravating leaky gut. Moderation is key.

Foods to avoid include aged cheeses, nuts, aged meats, fermented foods, dried fruits, pickles, spinach, eggplant, avocados. Safe options include fresh meats/fish, fresh produce, potatoes, rice, gluten-free grains.  

With the guidance of your doctor, a histamine diet may provide relief from uncomfortable symptoms. But remember, such a restrictive approach is not sustainable long-term or necessarily healthy if followed rigidly without occasional reintroduction of foods. The ideal solution is maintaining balance – meeting your personal needs, supporting DAO activity, consuming histamine-rich foods in moderation, and keeping an open and flexible mindset.

Diagnosis and Measurement of Diamine Oxidase Activity

Proper diagnosis of patients with histamine intolerance typically involves measuring your diamine oxidase (DAO) activity and level. The main approaches for assessing DAO include:

Approaches for assessing DAO activityDescription
Serum DAO activity/levelA simple blood test can determine your serum DAO concentration, which reflects the amount of active DAO circulating in the blood. Lower serum DAO is associated with histamine intolerance.
Response to histamine challengeAfter fasting, patients are given a controlled dose of histamine and monitored for symptoms. Those with histamine intolerance tend to report discomfort, while others tolerate the histamine without issues. This helps validate other DAO findings.
DAO enzyme assayInvolving incubated serum and histamine substrate, the DAO enzyme assay directly measures DAO’s ability to break down histamines. Lower conversion of histamine indicates impaired DAO activity.
DAO genotypingSome doctors may test for common DAO gene variants that can influence enzyme function. Certain polymorphisms are linked with higher histamine intolerance risk.
Measurement of urinary histaminesUrine samples are checked for increased histamine metabolites, reflecting incomplete breakdown of histamines in the body. Higher histamine in urine points to reduced DAO activity.

Porcine kidneys have traditionally served as a source for DAO in diagnostic tests. DAO is highly concentrated in pig kidneys, so porcine kidney extract is often used to determine a patient’s ability to convert histamine substrate, indicating DAO activity and adequacy. Some lateral flow tests now use recombinant human DAO for at-home histamine intolerance screening as well. 

Histamine Intolerance in Special Populations

Certain populations deserve special consideration when it comes to histamine intolerance. This includes children and those with inflammatory bowel disease (IBD).

In pediatric patients, histamine intolerance may present differently than in adults. Digestive issues are already common in children, so symptoms alone do not definitively prove or rule out histamine intolerance. 

A combination of symptoms, response to diet changes, and diagnostic testing provide the clearest picture. Stricter elimination diets could compromise growth in children, so treatment aims for balancing nutritional needs with symptom relief. 

Histamine Intolerance for Individuals with IBD

Managing histamine intolerance also proves challenging in individuals with IBD. Underlying inflammation and damage to the intestinal lining already impact absorption and digestion. 

Patients take immunosuppressants that can further hamper immunity and DAO activity. Thus, both histamine intolerance diagnosis and management requires close collaboration between doctors, as reducing inflammation and finding the right diet plan tend to be complex.

Potential impact of intestinal permeability on histamine levels and diamine oxidase activity

Intestinal permeability, or “leaky gut”, deserves attention in these populations. When the intestinal barrier is compromised, larger molecules can pass through into the bloodstream, including histamines that should have remained confined to the gut. This places strain on the body’s ability to break them down, increasing histamine overload and sensitivities. 

Repairing permeability supports reducing excess histamines and maintaining health, especially for those with preexisting GI issues. Probiotics, glutathione, zinc, and omega-3 fatty acids help boost barrier integrity and DAO activity. However, supplementation must be carefully considered alongside medical treatments. 

In summary, histamine intolerance should be evaluated carefully in children, IBD patients, and anyone with a compromised intestinal barrier. The diagnosis and management process may differ in complexity and approach from that of the general population. By recognizing these special needs, considering both medical and diet-based strategies, you can help patients gain balanced histamine control and optimal wellbeing, even when conditions like IBD, pediatric illness or leaky gut make their situation more complex.


In summary, diamine oxidase activity and maintaining healthy histamine balance within your body deserve recognition and support. As the primary enzyme responsible for breaking down excess histamine from foods and maintaining inflammatory homeostasis, impaired DAO activity can negatively impact your health, digestion, immunity, and quality of life. 

Symptoms like nausea, hives, rashes, abdominal pain, headaches, and fatigue could signal histamine intolerance due to reduced DAO. Proper diagnosis through blood testing, genetic screening, and elimination diets helps determine if histamine overload from impaired DAO could be contributing to your discomfort. 

Schedule a Free Consultation at SeeBeyond Medicine

Management of histamine intolerance typically focuses on boosting DAO, reducing histamine triggers, healing gut damage, and restoring balance. Dietary changes, targeted supplements, probiotics, and medication/treatment of underlying conditions may all play a role depending on severity and cause. Pediatric, IBD, and other complex cases especially benefit from integrative, multidisciplinary care. 

Strictly following a histamine-free or low-histamine diet provides relief for some by limiting intake of high-histamine foods. However, long-term diet restrictions alone rarely address the underlying issue and may compromise health. A balanced, tailored approach under medical guidance offers the greatest likelihood of managing symptoms, improving quality of life, and regaining control of health and well-being.

With increased understanding of this system’s importance and complex relationships, you gain more power over your own health, even when conditions like chronic illness further complicate it. Focus on balance, support enzyme activity, minimize excess, heal damage, follow medical advice – and get back to enjoying the moments that really matter.

We are offering 30 minutes for free to talk to one of SeeBeyond's Functional Medicine Practitioners to create a personalized regimen.

Fill out the form below to schedule your consultation.

Request Consultation - Consultation Popup