The study of the concentration of the Diamine Oxidase (DAO) enzyme evaluates the rate of degradation of this enzyme present in the body. The DAO enzyme is essential for the metabolization of histamine, a molecule involved in allergic reactions, gastric regulation, and neurological functions. In the case of a deficiency, histamine cannot be degraded quickly enough and can lead to an accumulation of it, resulting in symptoms of histaminosis that include gastrointestinal problems, migraines, irritation of the nasal mucosa, and other adverse reactions.

A large number of foods contain histamine: some fermented foods, alcoholic beverages (especially red wine and cava), meats and fish, vegetables, fruits, nuts and seeds, among others. Other foods stimulate the release of histamine.