What is histamine intolerance?

What is histamine intolerance?

Histamine is an immune signalling protein found in some of the body’s cells, known as mast cells and basophils, that is released in response to injury or an allergic or inflammatory response. The body can produce histamine naturally in the body, or there are certain foods that either contain histamine or can stimulate the body to release histamine.

Histamine intolerance isn’t an intolerance to histamine but is in fact a sign that your body has built up too much histamine and is unable to break it down properly.

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Symptoms of histamine intolerance

Some of the common symptoms of a histamine intolerance include:

  • Itching skin or hives (urticaria)
  • Headaches or migraines
  • Nasal or sinus issues
  • Nausea or vomiting
  • Menstrual cramping or irregular periods
  • Digestive issues such as bloating or diarrhoea
  • Flushing
  • Low blood pressure or irregular heartbeat (arrhythmia)
  • Red, watery, or itchy eyes
  • Causes of high histamine

There can be several reasons behind why someone may have high histamine levels, including:

  1. Menopause or hormone imbalances – some of the cells in the body that produce histamine, known as mast cells, also have oestrogen and progesterone receptors. Oestrogen stimulates the mast cells to release histamine, and so if your oestrogen levels are too high this can drive high histamine. This can also be the case if progesterone levels are low in relation to oestrogen, which is common in menopause.
  2. DAO deficiency – DAO (diamine oxidase) is an enzyme that is involved in histamine metabolism. Some of us have a genetic mutation on this enzyme making it less effective and therefore less able to clear histamine. Oestrogen also reduces DAO activity, so again if your oestrogen levels are too high or progesterone levels are too low this can make it harder for your body to clear histamine. Eating foods high in histamine if you have a DAO deficiency will also drive high histamine levels.
  3. Allergies – histamine is part of our natural immune response but when someone with allergies is exposed to an allergen, it causes the mast cells to release histamine. This could be an allergy to pollen or dust (e.g hay fever) or a food allergy (e.g nuts or fish). In milder allergies this will cause symptoms such as itching, a runny nose or a tickle in the throat but in true allergies (IgE) it can trigger anaphylaxis which can be life threatening and require immediate medical attention.
  4. Digestive issues research is beginning to understand the role our microbiome plays in managing histamine, and that a greater abundance of histamine-producing bacteria could lead to the development of histamine intolerance. Those with an IBD (inflammatory bowel disease) may also have higher histamine levels which is not yet clearly understood but may be in part to mast cell activation in the gut, the microbiome or a DAO deficiency.
  5. Medications – some medications can affect histamine clearance and DAO activity, and therefore cause high histamine. These include antibiotics, NSADIs (e.g. ibuprofen), antidepressants and
  6. Mast Cell Activation Syndrome (MCAS) – this is a condition whereby a person experiences repeated severe allergy symptoms because the mast cells have increased in number, or are over-reacting or over stimulated, or both. The increased release of histamine is just one of the factors in MCAS, not the sole cause.


11 ways to reduce histamine load

There are several ways you can look to reduce or manage your histamine load, which includes:

  1. Avoid histamine-rich foods such as alcohol, fermented foods, and aged cheese
  2. Avoid foods that trigger a histamine release such as citrus fruit, chocolate, and tomatoes
  3. Avoid foods that block the DAO enzyme such as alcohol, tea, and energy drinks
  4. Follow a low histamine diet to reduce the amount of exposure to histamine
  5. Consume foods high in good fats along with some key nutrients such as zinc, iron, and magnesium
  6. Consume sprouted lentils as research has indicated they may be a plant-based source of the DAO enzyme
  7. Consider an antihistamine
  8. Work to balance your hormones which can include diet and lifestyle changes or hormone replacement therapy (HRT) in menopause
  9. Use Zeolite Clinoptilolite, a natural mineral, that can be taken as a supplement and research indicates that it is an effective chelator (binder) for removing histamine from the body through natural bowel movement
  10. Try other supplements such as vitamin C and quercetin which may help reduce histamine symptoms, as they are both natural antihistamines
  11. Try a probiotic - some bacterial strains can help to manage histamine levels, whereas others may increase histamine levels so make sure you speak to an expert when deciding.

Diagnosing histamine intolerance

Your doctor is likely to first rule out other more common causes for your symptoms such as a genuine food allergy or perhaps Coeliac Disease, which can present with similar symptoms. If they suspect a histamine intolerance, they are then more likely to make a clinical diagnosis rather than test but they may recommend a blood test to measure the DAO levels and histamine levels in your blood or recommend following a low histamine diet for a few weeks, perhaps working with a registered dietician, to see if this improves your symptoms.

Some private labs also offer a Histamine Intolerance Test which also checks for the concentration of DAO in the blood which may require a blood draw by a phlebotomist, or a finger prick sample which can be completed at home.

When it comes to sensitivity to histamine in foods, there is currently no reliable tests to diagnose this sensitivity (also known as vasoactive amine sensitivity) and so you may want to work with a registered nutritionist on a low histamine diet, whilst ensuring the rest of your diet remains balanced.


A histamine intolerance is quite rare, although more common in women because of the hormone link. If, however you suspect you have a histamine intolerance then it is recommended to work with an experienced health profession to understand what the driving factor or factors may be, and work to address them.

Call us on 02476363873 or email us at info@nhinnovations.com to discuss your questions with a member of our clinical team.

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