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A Beginner Guide to Histamine and DAO

Know All About Histamine

Histamine is a natural compound that is present within the human body and directs a large number of important functions in day-to-day life. The adaptability of Histamine positions it as a conductor in the intricate symphony of human physiology. To clearly understand Histamine, it is essential to understand the meaning and instances of physiological activities.

Physiological activities mean various processes and functions that take place within the human body at the cellular, tissue, organ, and systemic levels. These activities are vital for the crucial maintenance of life and the proper functioning of the body. The well-being of an individual heavily depends upon proper physiological activities and in the absence of which a list of health issues arises.

Key Roles of Histamine:

  • Histamine acts as a crucial neurotransmitter and is essential for maintaining normal brain functions and central nervous system.

  • Histamine takes center stage in digestion by signaling the release of gastric acid, initiating protein breakdown for efficient digestion.

  • Histamine also acts as a defender of the body's immune system and safeguards against threats like infection and trauma.

  • Histamine is essential for the robust defense mechanisms of the human body and prevents the occurrence of disease considerably.

Apart from these crucial functions, it is a multifaceted performer ensuring the seamless functioning of various physiological processes ranging from neurotransmission to digestion, immune response, and much more.

What is Histamine Sensitivity?

  • Histamine in excess of the body's requirements leads to the development of adverse effects.

  • Histamine-mediated reactions may be clinically indistinguishable from food allergy.

  • Histamine sensitivity is becoming recognized as a disease entity quite distinct from allergy.

  • "Idiopathic" urticaria and angioedema (hives) are examples of histamine sensitivity.

Understanding Histamine Sensitivity

Excess of anything causes problems and so does histamine. When there is an excess of Histamine in the body it tends to cause side effects that may get serious sometimes. The reactions caused by histamine are mostly similar to those of food allergies, however, with the advancements in the healthcare industry, it is feasible to understand the hidden causes too. Histamine sensitivity is detectable and it is quite different from regular allergies that hamper your normal routine. Conditions like "idiopathic" urticaria and angioedema (hives) show us that histamine sensitivity is more than just a symptom. It's its own separate health concern that requires special attention and care.

How Histamine Sensitivity Mechanism Works?

The excessive histamine level is controlled by two enzyme systems, viz;
Histamine N-methyltransferase (HNMT or HMT): Acts as a guardian, preventing prolonged binding of histamine to its receptors.
Diamine Oxidase (DAO): The superhero in this narrative, DAO swiftly degrades excess histamine to its inactive metabolites.

These metabolites find their way out through urine, ensuring a natural detoxification process.

In the mechanism of histamine sensitivity, maintaining optimal DAO levels and function emerges as a strategic move. This not only keeps histamine in check but also opens avenues for effective control. By understanding this mechanism one can develop potential strategies for managing histamine sensitivity, paving the way for a harmonious balance in the body.

Identifying Effects of Excessive Histamine


  • Flushing

  • Reddening


  • Tachycardia (increased heart rate)

Increased Vascular permeability:

  • Urticaria (hives)

  • Angioedema (Swelling)

  • Rhinorrhoea (runny nose)

  • Otitis media (earache)

Pruritus (itching)

Increase in gastricsecretions:

  • Heartburn

  • Reflux

  • Night work / shift work

Symptoms of anxiety: panic attack

Fatigue: listlessness


Mechanism of histamine sensitivity

Excess histamine is controlled by two enzyme systems:

  • Histamine N-methyltransferase (HNMT or HMT)

  • Diamine Oxidase (DAO)

Normally DAO rapidly degrades histamine to its inactive metabolites, which are excreted in urine.

HMT prevent prolonged binding of histamine to its receptors

Supporting DAO levels and DAO function can be an effective strategy for controlling histamine.

Histamine in Foods

FMD Histamine

Histamine is produced by microbial action in manufacture of foods such as:

  • Vinegar

  • Yeast extract

  • Sauerkraut

  • Cheese

  • Wine

  • Beers

  • Fermented meats and sausages

FMD Histamine

Histidine, a naturally occurring amino acids in foods, can be converted to Histamine by intestinal bacteria. Histidine may develop in fish that have been improperly processed or refrigerated, especially:

  • Tuna

  • Mackerel

  • Bonito

  • Bluefish

  • Mahi Mahi

  • Shelfish

FMD Histamine

Some foods naturally contain histamine, such as:

  • Spinach

  • Aubergine (eggplant)

FMD Histamine

Some foods develop histamine during the ripening process:

  • Tomatoes

  • Cherries

Histamine releasers and blockers

Some compounds cause the release of histamine:

  • Benzoates (commonly used as preservatives, canalsooccur naturally)

  • Tartrazine and other azodyes (commonly used color ingagents.)

Some compound block the action of DAO & HNMT:

  • Alcohol

  • Some antidepressants (e.g. Prozac, Zoloft)

  • Some prescription and OTC pain relivers (e.g. aspirin, ibuprofen)

  • H2 blockers (Tagamet, Zatac)

The role of diamine oxidase (DAO)

  • Diamine oxidase (DAO) is the first-line defense against histamine ingested through the diet or released within the gut.

  • When DAO levels are adequate and there is normal DAO activity, only a small portion of extrinsic (Outside) histamine enters circulation.

  • Those who consume a histamine-rich diet and/or use medications that block DAO activity experience greater sensitivity to extrinsic histamine.

  • Histamine restricted diets and DAO supplementation can be effective strategies for managing histamine sensitivity.

  • Diamine oxidase (DAO) supplements should be taken 15 minutes prior to consumption of histamine rich foods.

  • Those who take medications that block DAO activity may benefit from taking DAO supplements daily regardless of diet.

  • While DAO supplementation can be helpful, dietary restriction may also be necessary to properly manage histamine sensitivity.

FMD Histamine