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The report provides useful context for understanding how DAO helps break down food-derived histamine and supports normal and healthy histamine metabolism.*
Histamine, digestive, and immune health
Histamine is a naturally occurring compound with important roles throughout the body. In the digestive tract, it helps regulate stomach acid production and intestinal activity. Histamine also acts as a signaling molecule in the immune and nervous systems. Levels of histamine in the body reflect a balance between what is produced, consumed in foods, and broken down through normal metabolism.
The body naturally produces histamine. It can also come from foods and certain microorganisms in the gut. The amount in food can vary depending on how it is prepared, fermented, and stored. Foods that may contain higher amounts of histamine include aged cheeses, fermented foods, processed meats, and certain fish.
What is diamine oxidase (DAO)?
Diamine oxidase (DAO) is an enzyme produced by cells in the intestinal lining. It helps break down food-derived histamine in the digestive tract before the histamine enters circulation. This process supports normal and healthy histamine metabolism.
DAO activity can vary from person to person. Genetics, certain medications, intestinal health, and the amount of histamine consumed in foods may all influence DAO activity and histamine metabolism.
A DAO enzyme supplement provides additional DAO activity to help break down histamine from foods.* General digestive enzymes help digest proteins, fats, or carbohydrates. DAO, on the other hand, acts specifically on histamine. For this reason, a DAO supplement for histamine digestion provides targeted support for food-derived histamine.* A histamine metabolism support supplement containing DAO provides this targeted enzyme activity and may also be described as a digestive enzyme for histamine support.*
How DAO enzyme breaks down histamine
DAO helps break down histamine through a process called deamination. During this process, DAO changes histamine into other compounds that the body can process and remove.
In the digestive tract, DAO also helps break down food-derived histamine along the intestinal lining before it enters the bloodstream. This activity helps limit how much food-derived histamine the body absorbs.*
What did the case report explore?
The published report describes one woman’s experience with her diet over several years. She worked with a nutritionist on an elimination and reintroduction approach that identified onions and wheat as foods she chose to limit.
Several years later, in September 2024, she independently began using a DAO supplement before meals she believed might contain these foods. She continued using the supplement as needed, and her final post-supplement assessment occurred approximately three months later, in November 2024. The published report used the Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS), a standardized questionnaire, to describe her reported symptoms before and after dietary changes and DAO supplementation.
The woman chose to begin DAO supplementation on her own rather than as part of a controlled clinical trial. Because she had also used dietary strategies over time, the case cannot determine the contribution of DAO supplementation to the changes described.
The report is a narrative account of one person’s experience. It cannot show cause and effect, cannot tell us whether another person would have the same experience, and should not be used as a supplementation plan.
Key takeaways
- Diamine oxidase (DAO) is an enzyme that helps break down food-derived histamine in the digestive tract.
- Histamine has normal roles in digestion, immune function, and other processes throughout the body.
- A DAO enzyme supplement provides additional enzyme activity to support normal and healthy histamine metabolism.*
- In the published case, the woman used dietary strategies before independently beginning supplemental DAO before meals that might contain foods she chose to limit.
- Because the report describes one person’s experience, it is not evidence of effectiveness, cannot establish cause and effect, and cannot predict how another person will respond.
Frequently asked questions
- What foods may contain higher amounts of histamine?
- Histamine can be found in many foods. The amount can vary depending on how foods are prepared, fermented, and stored. Foods that may contain higher amounts of histamine include aged cheeses, fermented foods, processed meats, and certain fish.
- What is a DAO enzyme supplement?
- A DAO enzyme supplement provides additional diamine oxidase activity to help break down food-derived histamine.*
- How does DAO differ from other digestive enzymes?
- DAO is a digestive enzyme, but it has a more specific function than many other digestive enzymes. While enzymes such as proteases, lipases, and amylases help digest proteins, fats, and carbohydrates, DAO helps break down food-derived histamine in the digestive tract.*
- What are the roles of histamine in the body?
- Histamine is a signaling compound with several normal roles in the body. It helps regulate stomach acid production and intestinal activity and is also involved in immune responses and communication within the nervous system. The body naturally produces histamine, and it can also come from foods.
- What can we learn from a single case report?
- A case report provides a detailed account of one person’s experience and can raise questions for future research. However, it is not evidence of effectiveness, cannot establish cause and effect, and cannot predict how another person will respond. Always consult your health-care practitioner before beginning a new diet or supplement regimen.