DAO deficiency is the functional lack of the main digestive enzyme responsible for the histamine elimination, a molecule found in food. Diamine oxidase enzyme or DAO is located in the intestinal mucosa mainly, thus acts during the digestion of food. When there is an alteration in the metabolism of histamine and there is not enough DAO activity, the imbalance between ingested histamine and histamine released from the storage cells leads to histamine accumulation in plasma and the occurrence of adverse effects on health.
The main cause of the enzymatic dysfunction has a genetic origin. Some people have or produce few Diamine Oxidase, this is the reason why until recently, migraine was believed to be hereditary, when in fact; the hereditary factor is the deficiency of DAO. Moreover, drugs or some inflammatory bowel diseases represent another factor that enables histamine decrease.
Unlike food allergy, the occurrence of symptoms or adverse effects is not linked to the intake of specific food; by contrast it can be related to a wide variety of food with different histamine contents. Symptoms can also occur even after the ingestion of products with low histamine levels. This imposed considerable difficulty when establishing a maximum tolerable dose; in fact, there is no clear consensus on this value.
The most typical symptoms are:
Migraine, headaches and/or dizziness.
Irritable Bowel Syndrome (diarrhea, constipation), Crohn disease, stomach pain, nausea and/or vomiting.
Hypotension, hypertension and/or arrhythmia.
Hives, edema, atopic skin, eczema and/or rash.
Nose congestion, rhinitis, asthma and/or sneezing.
Muscle pain, fibromyalgia and/or fatigue.
Bonepain.
