Skip to content
DE
Enzyme

Diamine Oxidase

Diamine oxidase (DAO) is an enzyme that breaks down histamine, mainly in the gut. Supplements are often made from pig kidney extract.

Gut HealthImmune Support

What it is studied for

The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.

Food SensitivitiesGut HealthModerateBNo linked study
Histamine & Immune BalanceImmune SupportSmallCNo linked study
Gut healthSmallCNo linked study
Digestive sensitivityGut HealthSmallCNo linked study
Microbiome healthGut HealthSmallCNo linked study
Gut IntegrityGut HealthSmallCNo linked study
All 7 rated effectsGrouped by health goal, with the publications behind each rating

What is DAO meant to do?

Diamine oxidase helps break down histamine in the gut. Oral supplements aim to reduce food-related histamine exposure; that proposed mechanism does not establish which symptoms will improve. 1

Why people take it

Gut Health30%
Immune Support30%
Detox15%
Inflammation15%
Stress & Mood5%
Essential Health5%

SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.

Questions people ask

Does a low DAO blood test confirm histamine intolerance?

No. The guideline does not consider serum DAO a reliable diagnostic test. 2

Were capsules studied with meals?

The four-week pilot used them before meals, but that study design does not establish an effective personal regimen. 1

Did the migraine trial prove benefit over placebo?

No significant between-group difference was found despite improvement within the DAO group. 3

Should every suspected histamine-containing food be avoided?

The guideline favors individualized assessment and dietary adjustment over blanket long-term restrictions. 2

Sources

  2. Guideline on management of suspected adverse reactions to ingested histamine DGAKI, GPA, AeDA, SGAI and ÖGAI; Allergologie Select, 2021