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  • Writer's pictureAshley Sauvé Health

Gut Health and Histamine Intolerance

If you struggle with allergies (seasonal or otherwise), hay fever, rashy skin, and watery, itchy eyes, you’ll be no stranger to this naturally occurring substance: histamine.

Most people who struggle with allergies and hayfever will be familiar with using a subset of drugs called “anti-histamines” to help manage their symptoms. These products help to “block” histamine, which really helps with the symptoms associated with it!

In this article, we’re going to dig deeper into what histamine is, and how it relates to your gut health.

What is Histamine?

Histamine is a substance that has roles in the function of the immune system, digestive system, and central nervous system.

As it relates to our immune system and allergies, it’s released from the mast cells in response to a foreign allergen or ‘antigen’ (something that the body doesn’t recognize, and perceives as a potential threat!), in order to neutralize the threat.

This response can cause a number of symptoms that we associate with having allergies: things like congestion, hay fever, coughing, a runny nose, rashes or hives, shortness of breath, itchy, watering eyes, etc.

Histamine is also a naturally occurring substance that is found in foods like fermented foods (kimchi, natto, sauerkraut, kombucha, etc.), cured meats and cheeses, wine, nuts, seeds, and some fruits and vegetables.

Histamine, as you can maybe guess from the title of this article, also plays an important role in our gut!

As far as digestive function goes, histamine plays a role in the secretion of stomach acid, which aids in the digestion of protein, and helps to neutralize pathogens.

What is Histamine Intolerance?

In order to keep histamine levels managed in the body (and not in excess), there are two enzymes that actually degrade histamine: DAO, or diamine oxidase (which is the predominant one that's secreted in the gut to degrade histamine there), and HNMT, or histamine n-methyl transferase.

When there aren’t adequate amounts of these enzymes available to break down excess histamine, we can start to see symptoms develop, like the ones mentioned above.

Histamine intolerance can be tough to pinpoint, because it can create a variety of symptoms, across many systems in the body. It can affect digestion, our skin, our neurological function (think brain fog, headaches, fatigue), and even contribute to things like joint pain, heart palpitations and increased blood pressure.

In the gut, we often see histamine tolerance arise as it relates to the enzyme DAO. When we have histamine in the digestive system, whether because of histamine-containing foods, bacteria that release histamine, or the immune system’s response to allergens or antigens in the gut (such as in the case of leaky gut!), DAO can have a hard time keeping up with the demand, leading to symptoms.

Symptoms of Histamine Intolerance

As histamine has its hands in many systems throughout the body, it’s understandable that symptoms associated with it will reflect that!

Here are some of the symptoms associated with histamine intolerance:

  • fatigue

  • brain fog

  • headaches (or migraines)

  • digestive complaints (diarrhea, bloating, cramping, constipation, nausea, etc.)

  • rashes, hives, flushing

  • nasal congestion

  • swelling

  • itching, watery eyes

  • shortness of breath

  • dizziness

  • racing heart, heart palpitations

Histamine Intolerance & your Gut

There are a few ways in which histamine intolerance can be related back to what’s happening in your gut.

Let’s explore a few of them:

Low DAO Output

DAO is the enzyme you were introduced to above, that helps to breakdown excess histamine; especially histamine local to the GI tract.

DAO is actually produced within the intestinal lining. When we have conditions that impact the health and integrity of the intestinal lining (such as in the case of Chron’s disease or Ulcerative Colitis), we can see DAO levels impacted as a result.

Likewise, if there is intestinal permeability (aka “leaky gut”), or a blunted brush border present, the intestinal lining may not be able to adequately made and secrete DAO to keep histamine levels at bay.

These situations can result in an excess of histamine in the gut, and ultimately histamine intolerance.


Dysbiosis is an imbalance in the microbiome — whether it’s a lack of beneficial flora, an overgrowth of opportunistic flora, or even an overgrowth of normal flora, but in the wrong spot (like in the case of SIBO) — we can see an increase in inflammation and intestinal permeability.

We know that this damage to the intestinal lining can result in a lacking of DAO to manage histamine levels in the gut, which again, can ultimately lead to histamine excess and intolerance.

If you’re struggling with the symptoms mentioned above, and think you may be struggling with a histamine intolerance, it could be important to rule out any imbalances in the microbiome that could be contributors.

Navigating Histamine Intolerance

So you think you’ve got a histamine intolerance. What do you do?

Here are some things to consider:
  • Focus on eating anti-inflammatory foods, and experiment with avoiding high-histamine foods. Following an “anti-inflammatory diet,” or avoiding common offenders and allergens can take a lot of stress on the body, and contribute to an environment that supports good digestive function. To go one step further, you can be mindful about avoiding high-histamine foods, which can help reduce symptoms associated with histamine intolerance.

  • Address any underlying imbalance or infection in the GI tract that could be compromising the integrity of your intestinal lining. This is really important, as this can help address root causes associated with why you’re experiencing histamine excess and intolerance. I help my clients to explore this via GI MAP stool testing in my program Gut Rehab, which you can learn more about here.

  • Avoid consuming foods that block the DAO enzyme. Believe it or not, certain foods actually block the DAO enzyme production. Things like alcohol (which is also a high-histamine beverage), black tea, mate tea, etc. can block the production of this enzyme, leading to excess histamine.

  • Make sure you’re getting the nutrients you need to make DAO! Nutrient deficiencies can also be at play here. Ensure that you’re getting adequate vitamin C and copper (which are required to make DAO), as well as vitamin B6 (which is cofactors to DAO).

Getting Help

If you figure you’re dealing with histamine intolerance, because you’re experiencing many of the symptoms mentioned above, and you’ve tried the recommendations here, it could be worth looking for some support with this.

In my program Gut Rehab, I help my clients to investigate their microbiome, and digestive function, through the GI MAP comprehensive stool test. This can help us get a better idea of the health of your microbiome, your mucosal barrier and intestinal lining — which can all ultimately impact histamine intolerance!

To learn more and book in a free Q&A call, you can click here.

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