Diamine oxidase (DAO)
Diamine oxidase (DAO, also called histaminase) is an enzyme in the gut lining that breaks down histamine from food. It is the main pathway for clearing ingested histamine (the intracellular pathway is handled by the enzyme HNMT).
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Why it matters
Low activity is associated with reduced histamine breakdown; the test is not definitive.
If it’s low
Reduced DAO SUGGESTS possible reduced histamine breakdown but does not prove it — many people with low DAO have no problems, and vice versa. It is meaningful only with matching symptoms and a doctor's assessment.
If it’s high
High DAO is usually not clinically significant. During pregnancy, DAO rises sharply as a normal physiological change (the source is the placenta).
What to do
A result alone without symptoms usually does not require action. If you have recurrent problems after histamine-rich food (aged cheese, wine, fermented foods, canned fish), discuss a trial of a low-histamine diet and a possible DAO supplement with a physician or dietitian. Alcohol and some medications can further lower DAO.
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This content is for information only and is not a substitute for medical advice. Talk to your doctor about your results.
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