Diamine Oxidase (DAO) Deficiency

This content is for general educational and informational purposes only and does not constitute medical advice or a diagnosis of any health condition.

Diamine oxidase, commonly referred to as DAO, is an enzyme the body produces naturally in the lining of the small intestine. Its primary role is to support the breakdown of histamine from high-histamine foods and beverages you consume before that histamine can be absorbed into the bloodstream. When the body's natural DAO enzyme activity is taxed or stressed, dietary histamine may accumulate in the digestive tract and potentially be absorbed into circulation, where it may interact with histamine receptors throughout the body. The term DAO deficiency is used in the scientific literature to describe a functional reduction in DAO activity, and it is understood in published research to be associated with what is commonly referred to as histamine sensitivity or histamine intolerance (HIT).

What is DAO deficiency?

DAO deficiency is not classified as a disease. It is a functional reduction in enzyme activity that may be associated with a range of factors, including individual genetic variation, age, hormonal changes, certain medications, alcohol consumption, and alterations in gut health. For more clinically peer-reviewed information, the National Institutes of Health maintains published research on diamine oxidase and its role in histamine metabolism.

What is histamine?

Histamine is a naturally occurring compound found throughout the human body and in many foods and beverages. When DAO enzyme activity is reduced, the body may have a diminished capacity to break down histamine from dietary sources such as aged cheeses, fermented foods, cured and processed meats, alcoholic beverages, smoked fish, and certain fruits and vegetables with elevated histamine content or histamine-liberating properties. The potential accumulation of histamine in the gut associated with reduced DAO activity is an area of active scientific inquiry.

Histamine receptors are found throughout the body, including in the digestive tract, skin, sinuses, cardiovascular system, and neurological pathways. Published research on dietary histamine sensitivity describes a range of experiences that vary widely between individuals and are dose-dependent, meaning that sometimes you can notice these effects and other times not as much, depending on how many high-histamine foods you are consuming in combination with the above-mentioned factors (hormonal fluctuations, stress, etc.).

These experiences are not specific to any single diagnosable condition with available diagnostics at this time and this content is for eductional purposes only for awareness and to help you determine if you could benefit from DAO supplementation. If you experience symptoms that concern you, consult a qualified healthcare provider. The National Institutes of Health provides additional peer-reviewed research on histamine and enzyme activity.

How does DAO help histamine?

Supporting the body's natural DAO enzyme activity through dietary supplementation is one approach some individuals explore in consultation with their healthcare providers. Diamine oxidase dietary supplements supply the DAO enzyme that the body produces naturally to support the breakdown of dietary histamine in the gut. When taken before consuming high-histamine foods or beverages, a DAO dietary supplement may support the body's natural histamine management process in the small intestine before histamine is absorbed into the bloodstream. 

How do DAO supplements help Histamine Intolerance?

OmneDiem produces a family of DAOgest®-based diamine oxidase dietary supplements formulated to support the body's natural DAO enzyme activity. DAOgest® is a naturally derived, high-quality, clean, porcine-sourced DAO enzyme with an established safety and activity profile in published scientific literature. All OmneDiem® Histamine Digest® products use a designed-release capsule technology formulated to activate in the small intestine, where dietary histamine is processed.*

OmneDiem Histamine Digest 60 or 120 Capsules 

OmneDiem Histamine Digest with DAOgest® delivers naturally derived diamine oxidase (DAO) in an enteric matrix for release in the small intestine to help your body fight dietary histamines. Supports digestive health and comfort. Supplies 30,000 HDU of DAOgest® DAO enzyme per designed-release capsule to support the body's natural histamine breakdown process in the gut.

OmneDiem Histamine Digest 360

Advanced Histamine Management for Gut & Immune Health – Designed by a Functional Naturopath, this supplement provides Diamine Oxidase (DAO) and 1mg of activated Vitamin B6 (P5P) to support natural histamine breakdown. 

Unlike other DAO supplements, Histamine Digest 360 Mast Cell Support includes Pyridoxal 5'-Phosphate (P5P), the bioactive form of Vitamin B6, which serves as a crucial cofactor for DAO enzyme functionality. This combination helps support histamine metabolism, ensuring optimal breakdown of histamine in the gut and bloodstream. Ideal for individuals with histamine intolerance, food sensitivities, and histamine-related discomfort, this formula enhances DAO enzyme performance for better digestive health.

Designed for Sensitive Individuals & Clean Formula – Specifically formulated for individuals with mast cell issues, supplement sensitivities, and histamine intolerance, this DAO supplement is free from common allergens, synthetic additives, and preservatives. Unlike many alternatives, it does not contain catalase, ascorbyl palmitate, or unnecessary fillers, ensuring a gentle yet effective approach to supporting histamine metabolism. If you struggle with food sensitivities, skin flushing, or histamine overload, this clean formula is your best ally.

OmneDiem Histamine Digest PureMAX 60 Capsules

Supplies 40,000 HDU of pure DAOgest DAO enzyme per designed-release capsule with no added excipients beyond ultra-purified microcrystalline cellulose, formulated for those who may benefit from greater DAO enzyme support.

OmneDiem Histamine Digest Menopause Complete

Combines 30,000 HDU of DAOgest DAO enzyme with Estro8PN, flaxseed lignan extract, black cohosh, and citicoline to support the body's healthy response to the natural changes occurring during menopause and to support natural histamine levels and processing, which may be associated with hormonal fluctuations during the menopausal transition.

OmneDiem Drink HD

Supplies 30,000 HDU of DAOgest DAO enzyme per designed-release capsule. Formulated to support the body's natural histamine management when taken before consuming alcoholic beverages high in histamine.

*These statements have not been evaluated by the Food and Drug Administration. OmneDiem dietary supplements are not intended to diagnose, treat, cure, or prevent any disease or health condition. This content is for general educational and informational purposes only and does not constitute medical advice. References to third-party sources are provided for informational context only and do not imply endorsement of those sources or their content. Individual results may vary. Consult your healthcare provider before beginning any new supplement regimen, particularly if you are pregnant, nursing, taking prescription medications, or managing a health condition. OmneDiem Histamine Digest products contain a porcine-derived ingredient and are not suitable for individuals with pork allergies or those following vegetarian, vegan, kosher, or halal diets.