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Doctor's Assessment Included

Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.

Allergy & Intolerance

DAO (Diamine Oxidase)

DAO testing helps identify histamine intolerance — a common but underdiagnosed cause of recurring headaches, digestive complaints, and skin reactions. Including DAO in a preventive health panel provides actionable dietary insights.

What It Measures

This test measures the activity level of diamine oxidase in your blood. DAO is the main enzyme that metabolises histamine from food in the intestinal lining. Low activity suggests reduced capacity to break down dietary histamine.

Why It Matters

Histamine intolerance is often underdiagnosed because its symptoms overlap with many other conditions. Measuring DAO activity can help identify whether dietary histamine is contributing to your symptoms, guiding targeted dietary adjustments rather than broad elimination diets.

When to Test

Consider testing if you experience recurring symptoms such as headaches, flushing, digestive complaints, or nasal congestion after eating histamine-rich foods such as aged cheese, wine, fermented foods, or cured meats. Consult your healthcare provider for guidance.

Symptoms

Low Levels

Low DAO activity may be associated with symptoms of histamine intolerance including headaches or migraines, facial flushing, nasal congestion, digestive discomfort, hives, and in some cases heart palpitations. These symptoms typically appear after consuming histamine-rich foods.

High Levels

High DAO activity is generally not associated with clinical symptoms and suggests efficient histamine metabolism. No specific action is typically required.

Lifestyle Tips

If DAO deficiency is confirmed, a low-histamine diet may help manage symptoms. This involves limiting aged cheeses, fermented foods, cured meats, certain fish, and alcohol (especially red wine). A food diary can help identify personal triggers. DAO supplementation before meals is also used by some individuals under medical guidance.

Frequently Asked Questions

What is histamine intolerance?
Histamine intolerance occurs when the body cannot break down histamine efficiently, usually due to low DAO activity. Excess histamine from food accumulates and may cause symptoms resembling an allergic reaction.
Which foods are high in histamine?
Common high-histamine foods include aged cheese, red wine, beer, fermented foods (sauerkraut, kimchi), cured or smoked meats, tinned fish, and some fruits like strawberries and citrus.
Can DAO supplements help?
Some people with confirmed low DAO activity find that taking DAO enzyme supplements before meals reduces symptoms. Discuss this option with your healthcare provider before starting supplementation.