DAO (Diaminoxidase)
Diaminoxidase (DAO) is the enzyme that breaks down histamine in the gut. Reduced DAO activity causes histamine to accumulate in the body, triggering symptoms such as headaches, skin reactions, or digestive issues.
Background
DAO is primarily produced in the intestinal lining and is the main pathway for breaking down histamine from food. Various factors can impair DAO production: alcohol, certain medications, chronic intestinal inflammation, and hormonal fluctuations. In women, high estrogen levels can reduce DAO activity, which explains why histamine symptoms often occur in a cycle-dependent pattern. DAO activity can be measured in blood and is an important marker when investigating histamine intolerance.