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BHistamine Intolerance
Histamine intolerance can cause symptoms such as swelling, flushing, headaches, heart palpitations, nasal congestion, and digestive issues—especially after eating certain foods. This happens because the body has difficulty breaking down histamine, a compound found both in the body and in the food we eat.
The underlying cause may be a deficiency of the enzyme DAO (diamine oxidase), which normally breaks down histamine in the gut. When DAO levels are too low, histamine accumulates and causes reactions that resemble allergies—even though no allergies show up on tests.
Common triggers:- Wine, beer, aged cheese
- Chocolate, tomato, avocado
- Sauerkraut, shellfish, nuts
A simple blood test can measure your DAO levels and help determine whether histamine is the culprit behind your symptoms.
Histamine intolerance is a condition estimated to affect approximately 1–3% of the population, although the actual prevalence is believed to be significantly higher—especially among middle-aged women. This is partly due to the non-specific nature of the symptoms, and partly because awareness of the condition remains low within healthcare. Many individuals are told they are simply stressed, have IBS, or are "just sensitive," when in fact the root cause may be a biochemical imbalance in how the body processes histamine.
What is histamine and why can it become problematic?
Histamine is a naturally occurring signaling molecule involved in allergic reactions, wound healing, gastric acid regulation, and other physiological processes. It is also present in many foods—particularly those that are fermented, aged, or preserved, such as cheese, wine, sauerkraut, smoked fish, and shellfish.
Under normal circumstances, histamine is broken down in the intestines by the enzyme diamine oxidase (DAO). However, if DAO levels are too low, or if dietary intake of histamine exceeds the body's capacity to metabolize it, histamine can accumulate. This can lead to symptoms resembling an allergic reaction—even in the absence of any detectable allergy on testing.
Low DAO levels may be genetically determined but are more commonly linked to gastrointestinal issues such as SIBO, dysbiosis, intestinal infections, or damage to the gut lining. Certain medications (e.g., antidepressants, NSAIDs, proton pump inhibitors) and alcohol can further impair DAO function.
Symptoms of histamine intolerance
- Skin symptoms: flushing, itching, urticaria (hives)
- Gastrointestinal symptoms: bloating, pain, diarrhea
- Headache or migraine-like symptoms
- Heart palpitations or anxiety-like sensations
- Nasal congestion, runny nose, respiratory symptoms
- Swelling of the face or throat
- Menstrual irregularities, PMS, fatigue
Common dietary triggers in histamine intolerance
Numerous foods may either contain high levels of histamine, stimulate histamine release in the body, or inhibit its breakdown via DAO. Examples of histamine-rich foods include:
- Fermented products: wine, beer, aged cheeses, sauerkraut, kombucha
- Canned or smoked foods: tuna, sardines, salami, ham
- Vegetables and fruits: tomato, spinach, eggplant, avocado, banana, citrus
- Other common triggers: chocolate, nuts, strawberries, shellfish
In addition to diet, factors such as alcohol consumption, stress, infections, and certain medications can exacerbate symptoms by either increasing histamine release or inhibiting DAO activity. Identifying individual triggers is therefore an important part of symptom management.
Why Does Histamine Intolerance Occur?
Histamine intolerance usually arises from one or both of the following causes: either too much histamine is produced or accumulates in the body, or the body has a reduced ability to break it down. The result is a histamine overload, which can lead to a range of symptoms.
Overproduction of histamine is often linked to impaired gastrointestinal health. It may be caused by food sensitivities, allergies, SIBO (small intestinal bacterial overgrowth), or dysbiosis—an imbalance in the gut microbiome. Certain gut bacteria can also produce histamine themselves, especially when the intestinal lining is damaged or inflamed. Consumption of histamine-rich foods can further exacerbate this.
Impaired histamine breakdown is often due to low levels of the enzyme diamine oxidase (DAO), which is normally produced in the intestinal wall. DAO’s role is to break down histamine from the foods we eat. When DAO activity is too low—due to factors such as genetics, gut disorders, inflammation, or certain medications—the body struggles to eliminate excess histamine, which over time may lead to intolerance.
How can you find out if you have low DAO levels?
Today, it is possible to measure DAO enzyme levels through a simple blood test. The test can help determine whether your body has sufficient capacity to metabolize histamine. While the test alone cannot provide a definitive diagnosis, it offers valuable insight—especially if you experience multiple symptoms associated with histamine intolerance.
A low DAO result, combined with relevant symptoms and a positive response to a low-histamine diet, strongly supports histamine intolerance as a contributing factor to your condition.
Gain insight – order a DAO test
If you suspect histamine may be the underlying cause of your symptoms, you can easily order a DAO blood test and receive a referral online. This test can provide clarity and guide your next steps toward improved health—whether that involves dietary changes, gut support, or targeted supplementation.
If you suspect histamine intolerance, you can request a referral for a DAO test to gain further insight.