DAO and Mast Cells: Two Pieces of the Histamine Puzzle

This page is for general educational purposes only and isn’t intended as medical advice. Talk with a trusted healthcare provider for your individual health needs.

If you’ve ever felt a bit “off” after consuming wine, aged cheese, or leftovers, histamine may be the reason why. Histamine build-up in the body usually comes down to two separate systems working — or struggling — at once: how well your body breaks down the histamine you ingest, and how much histamine your own cells release internally.

Read on for more information about both pieces of this puzzle: diamine oxidase (DAO), the enzyme that handles dietary histamine, and mast cells, the immune cells that release histamine of their own, and how DAO supplements fit into supporting the first piece of that puzzle to help support your body’s natural clearing of histamine.*

What Does DAO (Diamine Oxidase) Do in the Body?

Diamine oxidase, or DAO, is a copper-dependent enzyme your body produces mainly in the lining of the small intestine. Its main job is breaking down histamine that comes from food — aged, fermented, and long-stored items tend to be highest in histamine — before it can pass into the bloodstream in large amounts.¹ Research describes DAO as the gut’s major protective barrier against dietary histamine, with activity that increases along the length of the small intestine, from duodenum to ileum.¹

Third-Party Review

Inner Body named OmneDiem Histamine Digest PureMax its “Best High-Dose” DAO supplement, citing its 40,000 HDU per capsule — the highest DAO activity in their guide — along with its DAOgest® enzyme and third-party testing.*

What Are Mast Cells, and Why Do They Release Histamine?

Mast cells are immune cells located throughout the body’s connective tissue, positioned to respond quickly to anything the immune system flags as a potential threat.²

• When triggered — classically when an allergy-related antibody called IgE binds to something the body reacts to — a mast cell releases, or “degranulates,” a burst of stored chemical messengers, and histamine is described as the most significant one released.²
• That released histamine widens blood vessels and recruits immune cells to the area, and can contribute to symptoms like flushing, hives, digestive upset, or head pressure.*
• Beyond that immediate response, mast cells also play a broader role in everyday physiology — including blood vessel function, immune defense, and wound healing — and researchers have studied their involvement in a wide range of conditions, from allergies and asthma to cardiovascular health.*⁴
• Mast cells are also linked to several recognized medical conditions, including allergic reactions, hives (urticaria), and disorders where mast cells become overactive or overabundant, such as mastocytosis and mast cell activation syndrome (MCAS).*²

How Do DAO and Mast Cells Fit Together in the Histamine Puzzle?

• DAO and mast cells sit on two different sides of the histamine equation: DAO is mostly about histamine coming from outside the body — the amount arriving through food — while mast cells are an internal source, releasing their own histamine as part of a normal immune response.
• The theory behind conditions like histamine intolerance is that when DAO activity is lower relative to the amount of histamine someone takes in, or when mast cells are especially reactive, histamine may build up faster than the body clears it.*
• Because everyone’s histamine tolerance is different, the most practical approach is to listen to your body — trying a low-histamine diet and a DAO enzyme supplement, and noting whether either makes a difference in how you feel.*
• Mast cell activation syndrome (MCAS) is a separate, recognized, diagnosable condition in which mast cells release their mediators too easily or too often, though researchers note there are still open questions about its underlying mechanisms and how it’s best diagnosed and managed.*²⁵⁶
• Anyone noticing a consistent pattern of symptoms after eating or during allergy season is best served by bringing it up with a healthcare provider rather than self-diagnosing.*

Support Your Body’s Histamine Breakdown

Mast Cell Support HD360 pairs a DAOgest® diamine oxidase enzyme with activated vitamin B6 (P5P) in a delayed-release capsule, formulated to help break down dietary histamine before it reaches the bloodstream.*

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What’s Inside Mast Cell Support HD360?

• 30,000 HDU of DAOgest® per capsule: a standardized diamine oxidase enzyme, sourced in the same porcine-derived form used in human clinical research on DAO supplementation — not a lower-activity plant-based substitute.*
• Delayed-release capsule technology: designed to release further along the digestive tract, closer to where DAO naturally does its work, instead of breaking down too early in the stomach.*
• 1mg of activated vitamin B6 (as P5P): the body-ready form of B6, a nutrient involved in a wide range of the body’s enzymatic processes.*
• A clean, sensitive-friendly formula: free from common allergens and synthetic additives.*
• Simple to work into your routine: one capsule, no loading phase or complicated protocol required.*

FAQ About DAO, Mast Cells, and Mast Cell Support HD360

Can Low DAO Activity and Reactive Mast Cells Happen at the Same Time?

They can. Since DAO and mast cells affect histamine from two different directions — one handling what you eat, the other releasing histamine internally — some people may find both pieces are contributing to how they feel, which is part of why research in this area is still developing.*

What Does an MCAS Flare-Up Feel Like?

An MCAS flare typically involves symptoms across at least two body systems at the same time.⁷ Cleveland Clinic lists possible symptoms as low blood pressure, lightheadedness, or fainting; flushing, hives, or swelling of the eyes, lips, tongue, or throat; abdominal cramping, diarrhea, or vomiting; and wheezing, coughing, shortness of breath, or a stuffy nose. Flares can range from mild to severe, and anyone experiencing throat swelling, trouble breathing, or signs of a severe allergic reaction should seek emergency care right away rather than waiting it out.*

What Is Often Mistaken for Histamine Intolerance?

• Food allergies: A true food allergy is an IgE-driven immune reaction, while histamine intolerance is described as a “pseudoallergy” that can look similar — hives, flushing, digestive upset — without the same immune mechanism behind it.³¹
• Mast cell activation syndrome (MCAS) and mastocytosis: Because these conditions involve a much broader release of chemical mediators, researchers recommend ruling out mastocytosis with a tryptase test before diagnosing histamine intolerance.¹
• Irritable bowel syndrome (IBS): Cleveland Clinic notes that experts disagree on whether histamine itself is responsible for symptoms in some cases, or whether IBS or another condition is producing symptoms that simply look like histamine intolerance.³

Because of this overlap, working with a healthcare provider to help rule out other causes is an important part of getting an accurate picture of what’s going on.*

One Capsule, Two Systems Supported

DAOgest® DAO enzyme plus activated vitamin B6, in a delayed-release capsule built for sensitive digestive systems.*

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*See full disclaimer below.

*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.