DAO stands for diamine oxidase, an enzyme involved in breaking down histamine. Oral DAO supplements are marketed for dietary histamine, but their role and the evidence behind them should be considered carefully.

What a supplement can and cannot establish

Taking a DAO product does not diagnose histamine intolerance. Improvement or lack of improvement can have several explanations. Oral DAO is not a substitute for antihistamines, adrenaline or a medical assessment.

Understand the evidence

Studies of DAO supplementation are generally small and evidence remains limited. A guaranteed benefit, an absence of side effects or a cure for histamine intolerance should not be assumed.

Compare the complete formulation

Check enzyme activity, source, additional ingredients, allergens and the directions on the current Australian pack. Milligrams alone are not a reliable basis for comparing products. Ask a pharmacist or doctor about suitability alongside your medicines and conditions.

Plan and review

If your treating practitioner considers a trial reasonable, agree on what to monitor and when to review it. Browse the Australian histamine range for current product details, and read our histamine guide.

Further reading: Research review: histamine intolerance.