Is DAO Clinically Tested?
The Science
Why DAOgest®? The Most-Studied DAO in Histamine Digest® 30,000 HDU
Not all diamine oxidase (DAO) is backed by the same research. DAOgest®, the porcine-derived DAO in OmneDiem® Histamine Digest®, has been studied in humans — a distinction most pea- and plant-derived DAO sources cannot yet claim.
As a dietary supplement ingredient, DAO is not intended to diagnose, treat, cure, or prevent any disease — and no supplement can make that claim. What the published research explores is whether DAO supplementation may support the body's normal histamine-metabolizing processes when taken before consuming high-histamine foods and beverages.*
4.2 mg DAOgest® DAO · take one capsule before your main daily meal.
The DAOgest® Research
Safety & tolerability of DAOgest® supplementation
An observational study published in Clinical Nutrition ESPEN evaluated the effects of DAOgest® supplementation in 82 participants over 4 weeks. Each took a capsule containing 4.2 mg of DAOgest® DAO before their main daily meal.[1] *
The published authors reported improvements from baseline across multiple self-reported symptom subcategories, evaluated weekly, including gastrointestinal, skin, nervous, respiratory, and circulatory categories. These findings are reported in the peer-reviewed literature and are not claims made by OmneDiem® about its products.[1] *
Enzyme activity & intestinal absorption
A separate Clinical Nutrition ESPEN paper characterized DAOgest® in vitro, evaluating its enzymatic activity and capacity for intestinal absorption — the kind of ingredient-specific characterization that pea- and plant-derived DAO sources generally lack at this level of detail.[2] *
Porcine DAO alongside a low-histamine diet
A clinical trial examined the effects of porcine DAO supplementation in individuals with low serum DAO levels and nonspecific, recurrent gastrointestinal concerns who were following a low-histamine diet. Participants took 4.2 mg of extracted porcine kidney protein before meals for one month, with the authors reporting reductions in self-reported gastrointestinal discomfort across measures including bloating, nausea, and abdominal complaints.[3] *
~20 studies & an ongoing controlled trial
To date, roughly 20 studies have investigated a low-histamine diet and/or DAO supplementation — the vast majority using porcine-source DAO — in relation to experiences associated with histamine sensitivity, with promising results reported throughout the literature.[4] *
Research is ongoing. A prospective, double-blind, randomized, placebo-controlled trial at the University of Barcelona is currently comparing head-to-head porcine- and plant-based DAO supplementation.[5] *
DAOgest® vs. Pea-Derived & Other DAO Sources
DAO can be sourced from animal (porcine kidney), plant (pea/legume sprouts), and microbial sources. They are not equivalent — and the differences matter most when it comes to human evidence and regulatory standing.
| DAOgest® (Porcine Kidney) | Pea / Plant-Derived DAO | Microbial / Other | |
|---|---|---|---|
| Human clinical research | Multiple human studies, including the 82-participant DAOgest® study[1] | Largely in-vitro / lab-stage; lacks large human trials[6] | Early-stage; mainly food-degradation research[7] |
| Regulatory status (EU) | Authorized novel food since 2017[4] | Not authorized as a novel-food DAO supplement[4] | Not authorized as a DAO supplement |
| In-vitro enzyme activity | Well-characterized; consistent activity[2][6] | Can show high lab activity, but variable by batch[6] | Variable; source-dependent[7] |
| Open safety questions | Tolerability assessed in human study[1] | Some legume sources studied for β-ODAP content[8] | Limited published human safety data |
Note: Some pea-sprout (vegetal) DAO has shown high histamine-degrading activity in laboratory testing — in certain assays higher than porcine extracts. The key distinction is not lab activity alone but the depth of human research and regulatory review behind the ingredient.[6] *
Why the source behind your DAO matters
High activity in a test tube doesn't automatically translate to a meaningful experience after you swallow a capsule — enzymes must survive the digestive tract and act where food is. That gap between lab activity and real human use is exactly what clinical research is designed to test, and it's where DAOgest® has been studied while most pea- and plant-derived DAO has not yet caught up.[2][6] *
Choose the DAO that's actually been studied
OmneDiem® Histamine Digest® 30,000 HDU delivers 4.2 mg of researched DAOgest® DAO with Vitamin C and Catalase.
Shop Histamine Digest® →References
- Observational study to assess the efficacy and safety of diaminooxidase (DAO) supplementation in patients with histamine intolerance (HIT). Clinical Nutrition ESPEN. View study →
- In vitro characterization, evaluation of enzymatic activity and capacity of intestinal absorption of DAOgest (DAO extract from pig kidney). Clinical Nutrition ESPEN. View study →
- Schnedl WJ, et al. Diamine oxidase supplementation improves symptoms in patients with histamine intolerance. View study →
- Published reviews summarizing ~20 studies and the regulatory (novel-food) status of porcine kidney DAO for the dietary management of histamine intolerance. View review →
- Study protocol: prospective, double-blind, randomized, placebo-controlled trial comparing a low-histamine diet and porcine vs. plant-based DAO supplementation (University of Barcelona). View protocol →
- Lyophilised legume sprouts as a functional ingredient for DAO enzyme supplementation in histamine intolerance — comparing pea-sprout, porcine, and commercial DAO activity. LWT / Food Science. View study →
- Kettner L, et al. Evaluation of porcine diamine oxidase for the conversion of histamine in food-relevant amounts. Journal of Food Science. 2020;85(3):843–852. View study →
- Diamine oxidase from vegetal sources: germination study and investigation of β-ODAP content using LC-MS/MS. PMC. View study →
* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Research findings described above are reported by the cited authors and do not constitute claims by OmneDiem® about its products. Comparisons refer to the published research base and regulatory status of different DAO ingredient sources, not to the treatment of any condition. Individual experiences may vary. Consult your healthcare provider before beginning any supplement, particularly if you are pregnant, nursing, taking medication, or managing a health condition.