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 What is histamine?

Histamine is a vital compound found in nearly all human cells. It acts as a signalling molecule and neurotransmitter with a wide-acting effect on the smooth muscles, digestion, gastric secretions, heart and circulation. It is an important component of the immune system and is involved in the process of inflammation. In excess histamine causes a variety of symptoms depending on where it is released and what receptors it binds to. The most common symptoms caused by excessive histamine in the body are

  • Hives
  • Itchy eyes
  • Sneezing
  • Rapid heart rate
  • Low blood pressure
  • Headaches and migraines
  • Redness and tissue swelling 
  • Abdominal cramps and period cramps

What is histamine intolerance?

The actual mechanism of histamine intolerance (HIT) is under investigation but is thought to be related to a build up of histamine. In a healthy individual, histamine is broken down on a regular basis by two enzymes: DAO and HNMT. The mechanism of HIT is proposed to be a genetic or acquired impairment in one of these two enzymes. DAO is produced in the intestine, so if intestinal function is compromised there may not be enough DAO to degrade histamine normally.

When build up occurs, so do symptoms. Decreased DAO  (enzyme) production may be why HIT seems more common in persons with gastrointestinal disorders such as inflammatory bowel disease, IBS, celiac and SIBO. DAO activity can also be inhibited by certain medications.

Some physicians question the existence of histamine intolerance as a disease. HIT is more widely accepted in Europe as a true condition and was recognized in 2012 by the German Society for Allergology and Clinical Immunology as a true disease for which the pathophysiology has yet to be determined.

What are some of the symptoms of histamine intolerance?

  • Diarrhea 
  • Headache 
  • Flushing
  • Rash/Urticaria (hives)/eczema
  • Arrhythmia ( irregular heart beat)
  • Low blood pressure-due to vasodilation caused by the histamine
  • Wheeezing
  • Runny nose
  • Watery eyes
  • Angioedema-swelling of face/hands/lips
  • Heartburn-due to increased acid production
  • Itching- typically of eyes and skin
  • PMS- Headaches around the menstrual cycle or painful cramps due to histamine induced contractions in relation to hormone levels

Histamine intolerance appears to be more prevalent when there is underlying gastrointestinal dysfunction such as in inflammatory bowel disease, celiac disease, IBS etc. Given the minimal data on actual incidence of histamine intolerance, data on its correlation with other health issues is scant. In alternative medicine circles it is thought to occur more commonly with dysbiosis, Small Intestinal Bacterila Overgrowth (SIBO) and leaky gut.

It’s not the same as a food allergy

With histamine intolerance, symptoms can be triggered by certain foods, but the mechanism is different than a food allergy. Some of the symptoms mimic a true allergic reaction, but HIT is not mediated by IgE, so skin testing and blood allergy tests will be negative. HIT is thought to be due to a cumulative build up of histamine rather than an over-release of histamine. Because of this, the symptoms may not be immediate. Symptoms may be triggered any time your “threshold” is reached and it may be difficult to pinpoint a particular food as the culprit.

For example, you may have consumed histamine rich foods in the morning and in the afternoon consumed a low histamine meal. But, the afternoon food was enough to put you over your level of tolerance, so symptoms would occur in the afternoon. You would think your symptoms were due to the afternoon food but in reality your morning foods were a more important factor.

What to do if you think histamine may be a problem for you

If you think you may have histamine intolerance, speak to your physician to evaluate other possible “look-alike” conditions such as true allergies, mast cell disorders or underlying digestive disorders. Once these possibilities have been evaluated and addressed, an elimination diet may be initiated to see if symptoms improve. A food diary is essential. Underlying issues must be corrected first to optimize improvement. Because the diet is restrictive, especially if added onto an already restricted eating plan, please consult a professional to ensure proper nutritional intake.

How histamine intolerance is diagnosed

At this time there are no proven tests to diagnose histamine intolerance short of an elimination diet. While it is possible to measure blood DAO activity (one of the enzymes listed above), as well as histamine levels in the blood and urine, these results do not seem to correlate significantly with symptoms. Typical blood allergy tests or skin testing will not be positive, as HIT is not IgE mediated (like true allergies).

It is important to remember that while considering HIT as a cause of symptoms you must evaluate for related disorders such as true allergies, mast cell disorders, inflammatory bowel disease, celiac disease, fructose malabsorption, small intestinal bacterial overgrowth, colitis etc.

After evaluation for related disorders, a diet eliminating high histamine foods may be pursued. If symptoms improve when histamine is lowered or eliminated from the diet you may be histamine intolerant.

Treatment for histamine intolerance

It isn’t just diet! Treat any underlying disorder first, as this may improve histamine tolerance.

I generally like to focus on dietary treatments because I prefer to do as much as possible with diet in lieu of medication. But, histamine intolerance truly requires an integrative approach, as it often occurs in conjunction with other disorders that need to be addressed beyond dietary modifications.

Diet: A low histamine diet is the treatment of choice (food lists are below).This can be challenging if someone is already on a restricted diet such as a gluten-free or low FODMAP diet and should be done under the care of a health care practitioner so that proper nutritional intake is maintained. The tolerance to histamine varies from person to person and the amount of histamine tolerated must be deduced by trial and error. Some people can only tolerate very small amounts and others can be more liberal.

What is important to note is that tolerance to histamine seems to improve once underlying issues are addressed. For example; if IBS or SIBO are treated, reactions to histamine often decrease. It is imperative to treat the underlying disorder in conjunction with dietary changes. Once the elimination diet is completed one must individually assess tolerance to particular foods and liberalize the diet as tolerated so that optimum nutrition and lifestyle are attained.

Foods high in histamines

This is controversial as histamine content of food varies depending on duration of storage, ripeness or maturity, cooking and processing. Certain foods may also not be high in histamine yet are high in compounds known as histamine liberators which can trigger similar symptoms by increasing histamine levels.  The list below contains commonly accepted high histamine foods/histamine liberators, but this list is by no means exhaustive.  Available lists vary and consistent data is hard to find on histamine content of foods. What does seem to be agreed upon is that fermented and aged foods do tend to be some of the biggest culprits.

  • Alcohol: Champagne, red wine, beer, white wine,
  • Fermented or smoked Meats/Fish: Sardine, mackeral, herring, tuna,salami
  • Pickeled or canned foods: Sauerkraut, pickles, relishes, soy sauce
  • Fermented milk products: Yogurt, kefir, buttermilk
  • Aged cheeses: Parmesan, Gouda, Swiss, cheddar
  • Fruit: Dried fruit, strawberries, citrus
  • Vegetables: Tomatoes and tomato products, spinach
  • Legumes: Chickpeas, soybeans, peanuts
  • Other: Cinnamon, chocolate
  • Grains: Wheat

Histamine releasers: Citrus, papaya, pineapple, nuts, strawberries, egg white, additives

DAO blockers: alcohol, black and green tea

Relaxation: The benefits of relaxation techniques cannot be emphasized enough. Breathing exercises or progressive muscle relaxation are easy, portable and free. Yoga and meditation are great as well. Relaxation for you may also be reading, enjoying time with friends or playing music.

Medications: Antihistamines, topical steroids/creams, oral steroids, topical homeopathic or plant-based creams and lotions for rashes.

Supplements: Vit C, B6, Zn, Cu, Magnesium, Mangosteen, Quercetin, DAO promoters and supplements, topical creams. Please use any supplement under the guidance of a practitioner.

Histamine content apphttps://itunes.apple.com/us/app/food-intolerances/id419098758

Symptom tracker apphttps://itunes.apple.com/gb/app/mysymptoms-food-diary/id405231632?mt=8&ign-mpt=uo%3D4

Medications to use with caution if HIT is an issue

These medications inhibit the DAO enzyme:

  • Acetylcysteine
  • Aspirin
  • Ambroxol
  • Aminophylline
  • Amiloride
  • Amitryptiline
  • Cefuroxime
  • Cefotiam
  • Cimetidine (Tagamet)
  • Ciprofloxacin
  • Cyclophosphamide
  • Contrast Media
  • Docein
  • Haldol
  • Metamizol
  • Metoclopramide (Reglan)
  • Naproxen (Aleve)
  • Narcotics-Thiopental (IV med. for surgery)
  • Noscapene
  • Pancuronium
  • Prilocaine
  • Verapamil

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