Histamine in Your Body
Histamine is an amino acid with several important functions in the body. The one we’re all most familiar with is its role in the immune system: it gets released in response to an infection or injury to help attract other white blood cells to clean up the problem. Dysfunction of this process results in allergies: inappropriate immune response to an otherwise harmless “friend” (like foods, pets, pollen, etc) rather than a foe (a bacteria, virus, fungus, or external injury).
Histamine also functions as a neurotransmitter—specifically, it helps stimulate wakefulness, which is the reason why many of us notice that taking a Benadryl (an H1 histamine blocker) can make us drowsy.
In the stomach, histamine is also required for the first step in the release of gastric acid (HCl). This is why some of the most popular classes of drugs to block stomach acid are H2 (histamine receptor) blockers.
Two different enzymes are responsible for breaking histamine down, depending on where it is in the body: histamine N-methyltransferase (HMT) in the Central Nervous System as well as in other tissues, and Diamine Oxidase (DAO) primarily in the gut, as well as in other tissues.
Histamine in Your Food
Some foods naturally contain histamine, and some facilitate the release of histamine. Here are the big ones:
- Veggies: spinach, avocados, tomatoes, and white potatoes
- Fruits: citrus, strawberries, cherries, bananas, pineapple, kiwi, papaya, mango, raspberries, pears.
- Animal protein: anything processed (bacon, sausage, salami, pepperoni, etc); shellfish; fish that is not freshly caught
- Fermented foods: including yogurt, vinegar, alcohol, mushrooms
- Nuts and seeds: all of them
All of these foods require DAO in order to get broken down. In a healthy intestinal tract, that is no problem; but in the presence of gut inflammation, it can mean trouble.
Diamine oxidase levels can be used as a marker for decreased intestinal integrity. Lower DAO means increased circulating histamine levels… and increased circulating histamine levels throughout the body can mean any of the following symptoms:
- Arrhythmia or unusual heartbeats
- Rashes and hives
- Headaches and migraines
- Nasal congestion
- Abdominal cramping
Generally histamine intolerance is secondary to gut inflammation, which can be due to leaky gut syndrome, SIBO, Irritable Bowel Disease, Irritable Bowel Syndrome, gluten intolerance or Celiac Disease.
Some medications can also lower DAO function, particularly those that hit the gut. These include ibuprofen and aspirin, many antidepressants, and (ironically) both H1 and H2 blockers.
Treating Histamine Intolerance
Histamine intolerance isn’t a problem with release of histamine from mast cells; it occurs due to slowly increasing levels of histamine due to poorly functioning enzymes. In most cases, a low histamine diet, or eating high histamine foods with a DAO supplement, will lower the overall histamine levels enough for symptoms to subside.
But the real treatment is to heal the reason why histamine levels increased in the first place, which usually goes back to the gut.