What is histamine intolerance ?

Histamine intolerance (HIT) is a mechanism that is still under investigation from the scientific community. It is thought to be an accumulation of histamine. In a healthy patient, histamine is broken down by two enzymes : diamine oxidase and histamine N-methyltransferase. People suffering from histamine intolerance have trouble breaking down histamine. So over time, histamine builds up in their body until the level is too high and symptoms appear.

Symptoms can vary greatly from one person to another and seem unrelated. Hives, rashed, eczema, headaches, diarrhea, itchy eyes, runny nose, heartburn or abdominal pain are the most common symptoms.

According to research, HIT affects 1 to 3% of the population and particularly women over 40 years old.

Histamine intolerance looks and feels like an allergy but it’s not an allergy in the exact scientific term. Allergies are detected with the production of antibodies of the IgE type and reactions appear immediately. Histamine intolerance symptoms can take longer to appear.

What is histamine?

Histamines are chemicals produced by your immune system to get rid of foreign substances. So histamine is a natural substance that can be found :

  • In white blood cells, in basophils, circulating in the blood, and mast cells, located in tissues. When the body is in contact with a foreign substance like an allergen, histamine is released and generates an inflammatory response.
  • In the stomach lining,  where acid is produced.
  • In certain neurons, to control attention level and keep us awake.

Histamine can also be found in food to varying levels. Where things get complicated is that histamine levels change depending on duration of storage, ripeness or maturity, cooking and processing of foods. As a rule of thumb, it’s better to eat fresh produce and avoid processed, canned or ready meals.

How to diagnose histamine intolerance :

Unfortunately, there are no reliable test for histamine intolerance. You will probably read on other blogs that you can have your histamine or diamine oxidase levels tested with a blood sample. The problem is, it’s normal to have histamine in your body and it fluctuates wildy so it’s impossible to accurately determine your average histamine level. As for diamine oxidase, it’s also difficult to track in your body and it’s not the only histamine-degrading enzymes we know of (HNMT being the other).

So how can you figure out if you suffer from histamine intolerance ?

Well, the only way is to eat a low histamine diet and see if your symptoms improve or disappear. HIT sufferers have different  tolerance levels, so after completing the elimination diet, you will have to determine your threshold level by reintroducing foods (one at a time and monitoring your reactions).

What to eat on a low histamine diet:

  • Fresh fruits such as apples, apricots, blueberries, bananas (firm only).
  • All vegetables except for avocado (soft), broccoli, leek, spinach, pumpkin, eggplant, potatoes, tomatoes.
  • Grains: rice, corn, millet, oats, sorghum.
  • Fresh meat (avoid canned meat and fish)

What to avoid on a low histamine diet :

  • Fermented food : sauerkraut, pickles, relishes, soy sauce, yogurt, kefir, fermented cheese (cheddar, gouda, swiss cheese…) dried fruits, smoked meats
  • Histamine releasers:  pineapple, nuts, strawberries, citrus, egg white, additives
  • Wheat