Dietary histamine
A molecule made naturally in the body and present in many foods, especially fermented ones, whose build-up can cause reactions in people deficient in DAO (the enzyme that breaks down histamine).
Histamine is an important signalling molecule in immunity and inflammation. The body produces it AND takes it in through food. The enzyme DAO (diamine oxidase) normally breaks it down. But some people have a genetic or acquired DAO deficiency.
Foods rich in histamine: fermented cheeses, fish (especially preserved), cured meats, tomatoes, avocados, chocolate, raisins, mushrooms, cooked spinach and alcohol (red wine, beer).
Histamine-releasing foods (which cause mast cells to release histamine): eggs, strawberries, pineapple, shellfish.
Symptoms of histamine intolerance: migraines, hives, rhinitis, palpitations, fatigue and digestive upset.
A fresh angle: histamine intolerance is often confused with allergy because the symptoms overlap. Yet it is a metabolic intolerance, not an allergic one (no IgE). A low-DAO test can help with diagnosis.
A trap: probiotics containing histamine-producing strains of Lactobacillus and Bifidobacterium can make things worse in people deficient in DAO. Choose strains that do not produce histamine.