Diamine Oxidase (DAO) Test

The Diamine Oxidase (DAO) Test measures the activity of diamine oxidase, the primary enzyme responsible for breaking down histamine in the gut. This test is for anyone experiencing persistent or unexplained symptoms that may point to histamine intolerance, including recurrent headaches or migraines, flushing, hives or itching, nasal congestion, abdominal bloating, diarrhoea, or irregular heartbeat after eating histamine-rich foods such as aged cheese, cured meats, fermented products, and red wine. It is also useful for people who suspect a sensitivity to histamine-releasing foods or who have not responded to standard dietary and medical approaches.

DAO is produced mainly in the lining of the small intestine and is responsible for degrading ingested histamine before it enters the bloodstream. When DAO activity is low, histamine can accumulate and trigger a wide range of symptoms. Measuring DAO activity in a simple blood sample provides an objective indication of how efficiently your body is handling dietary histamine.

Biomarkers included

• Diamine oxidase (DAO) activity

Why it matters

Histamine intolerance is frequently overlooked because its symptoms overlap with allergies, digestive disorders, and hormonal conditions. A low DAO result can help explain chronic migraines, skin reactions, gut discomfort, and other histamine-related complaints, guiding targeted dietary changes and clinical management. Identifying reduced DAO activity allows you and your doctor to move beyond guesswork and address the underlying cause of your symptoms.

• Diamine oxidase (DAO) activity

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.