A Functional Medicine Approach to Histamine Intolerance

Dr. Shawn Greenan, DACM, CFMP®
A Functional Medicine Approach to Histamine Intolerance

What are Histamines?

Histamine is a compound stored in specific immune cells, including mast cells and basophils. The body releases the histamine to protect the body during an inflammatory or immune response to allergens. This is a normal part of a healthy, balanced immune system.


What Causes Histamine Intolerance

Many foods naturally contain histamine or trigger histamine to release in the body. Problems occur when there is a dysfunction or deficiency of the enzymes that break down histamine.

How Does This Happen?

DAO (diamine oxidase) is the enzyme responsible for breaking down histamine that you take in from foods. In a healthy individual with proper DAO levels, the histamine is broken down without any health complications.

But when this enzyme is deficient, histamine levels begin to rise in the body, causing “Histamine Intolerance.”

Reasons for DAO Enzyme Deficiency

  • Gastrointestinal disorders (leaky gut syndrome, IBS, and SIBO)
  • Nutrient deficiencies (certain nutrients are needed for DAO production)
  • Medications that block DAO functions (NSAIDS, pain medications, antibiotics, narcotics, and many other prescription drugs)
  • Mast cell conditions that increase histamine secretion are also commonly associated with symptoms of histamine intolerance

Histamine Intolerance Signs & Symptoms

The typical symptoms of histamine intolerance are digestive disorders with allergic-like reactions after consuming a high histamine food.

  • Flushing
  • Itching
  • Brain fog
  • Digestive problems
  • Eczema
  • Fatigue
  • Hormone imbalances
  • Migraines
  • Hives

In More Severe Cases of Histamine Intolerance, Patients May Experience:

  • Abdominal cramping
  • Tissue swelling
  • Irregular heart rate
  • Anxiety
  • Difficulty regulating blood pressure
  • Difficulty regulating body temperature
  • Dizziness

Functional Medicine Labs to Test for Histamine Intolerance

Current studies showed that testing DAO activity in serum is a valuable tool for differential diagnosis of histamine intolerance.

It should be performed in patients with symptoms like headache, tachycardia, urticaria, pruritus, diarrhea, and hypotension, where food allergy was previously excluded.

The Histamine and Zonulin test on the Rupa Health Portal is another excellent option that tests for both leaky gut syndrome and levels of histamine in the body via DAO levels.

Functional Medicine Treatment for Histamine Intolerance

High-histamine foods and histamine-liberating foods should be avoided as the first step in treatment.  

Generally, fermented foods have the highest histamine levels, while fresh, unprocessed foods have the lowest levels.

Unrefrigerated foods can grow bacteria that increase histamine so, eating fresh foods and freezing leftovers immediately can help reduce histamine loads.

By eliminating histamine-rich foods from your diet for several weeks (under the supervision of a practitioner) and then slowly adding them back in, you can learn more about your individual tolerance to foods triggering your histamine reactions.

High Histamine Foods

  • Fermented food (kefir, kimchi, yogurt, sauerkraut)
  • Alcohol (including wine)
  • Bone broth
  • Canned food
  • Cheese
  • Chocolate
  • Eggplant
  • Legumes (soybeans, chickpeas, peanuts)
  • Mushrooms
  • Nuts
  • Processed foods
  • Smoked meat products (bacon, salami, salmon, ham)
  • Shellfish
  • Spinach
  • Vinegar

Foods that Release Histamine

These foods are low in histamines but can trigger the release of histamine and create problems for people with histamine intolerance:

  • Avocados
  • Bananas
  • Citrus fruits (kiwi, lemon, lime, papayas, pineapple, plums)
  • Strawberries
  • Tomatoes

Supplements That Help Histamine Intolerance

Alongside a low histamine diet, A DAO supplement can help increase DAO levels in deficient patients.

Certain nutrients, including copper, vitamin B6, and vitamin C, may also help to support histamine degradation and DAO production.


Managing histamine intolerance involves making dietary changes, taking enzyme supplements, and avoiding or limiting the use of medications that trigger the release of histamine.

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Dr. Shawn Greenan, DACM, CFMP®
Acupuncture Physician Certified Functional Medicine Practitioner®
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