Contrary to food allergies, where the immune system is involved, histamine intolerance is considered to be more of a metabolic dysregulation. The body has an enzyme called diamine oxidase (DAO ...

Usually, DAO and, to a lesser extent, an enzyme called histamine-N-methyltransferase (HNMT) break down ingested histamine. But several factors can interfere with how DAO and HNMT work.

Up to 75% of women with histamine intolerance harbor genetic variations that lead to DAO deficiency, according to a study in the journal Biomedicine. Experts explain that variations in a gene ...