Medical Nutrition Therapy: Histamine Intolerance

Histamine is an organic substance produced by the body and found in certain foods. It’s a key player in many vital physiological processes such as immunity, sleep, and digestion. However, its most famous role may be as a modulator of the allergic response. When you encounter an allergen, your body produces histamine to induce physiological processes to get rid of it. This is what causes the uncomfortable symptoms usually associated with allergies — sneezing, itching, runny nose, and flushed skin.

Like many things, histamine is great in moderation but becomes a problem when in excess. An enzyme called diamine oxidase (DAO) usually breaks down histamine when it’s no longer needed. However, some people have low levels of DAO, which means that histamine can build up in the body. These people generally have a tough time tolerating high-histamine foods. It’s sort of like spending a lot of time outdoors on a spring day when you have a pollen allergy. 

Low DAO levels can occur naturally through genetic mutations or may be triggered by other medical conditions. Gut health is an important factor; as the body produces a large proportion of its DAO in the intestines, a damaged gut (as seen in conditions such as celiac disease or inflammatory bowel disease) may make you more susceptible to histamine intolerance. The condition is also linked to disruptions of the microbiome; certain intestinal bacteria can produce an enzyme that converts protein to histamine, which can lead to overload if there isn’t enough DAO available to break it down.

If you think you might have a histamine intolerance, which foods should you avoid? Histamine is present in certain vegetables such as spinach, avocados, and eggplant. Some foods also trigger your body to release histamine; these include, but are not limited to, tomatoes, beans, bananas, citrus fruits, chocolate, nuts, and wheat germ. Histamine levels increase with food aging processes, so those with histamine intolerance should avoid aged cheeses, smoked/canned fish, alcohol, and fermented foods such as sauerkraut and kombucha.

Histamine intolerance is a difficult condition to diagnose because there’s no definitive test for it and the symptoms are vague. Besides the classic allergy symptoms of sneezing, runny nose, and itching, you might experience headaches, anxiety, irregular menstrual cycles, insomnia, and dizziness. Therefore, the best way to tell is to eliminate high-histamine or histamine-producing foods and see if you feel better. Focus instead on fresh fruits and vegetables (except for the ones mentioned above), fresh meat/fish/poultry, and gluten-free grains. As a reminder, it’s always best to undertake any kind of elimination diet under the guidance of a registered dietitian.