Notebook with the word histamine on it next to a pair of glasses and stethoscope

The Truth about Histamine Intolerance – Symptoms and Causes

Histamine seems to be a big buzz word recently. A low histamine diet is becoming more popular and more people are wondering if this is a diet they should be following.

The term “histamine intolerance” is also floating about, giving us the allusion that some of us may be intolerance to histamine. 

But did you know that histamine is in each and every one of our bodies on a daily basis? So how could there be an “intolerance” to it?

Histamine “intolerance” is not a true intolerance in the sense that most of us would think. Read on to find out why. 

To understand what this term means, we need to understand what histamine is and what it does in our bodies. 

What is Histamine?

Histamine is a chemical that acts as a signaling “messenger” of sorts in our bodies. It alerts our immune system when there is an issue that the immune system needs to pay attention to.

An example of this may be a chronic dysfunction of some sort or even an infection. Histamine is involved in any type of allergic reaction that happens in the body. 

Sometimes, when we hear of people following a “low ______ diet” (fill in the blank), we tend to form a negative association with the substance that is being limited. In this case, a low-histamine diet may cause negative associations with histamine. 

But it’s important not to demonize histamine. As you can see, it is actually a mechanism within the body intended to help protect the host (us). 

So why would we want to limit histamine? Good question, and we will get to that. But first, we need to understand where histamine comes from. 

Where Does Histamine Come From? 

We mentioned that histamine is inside all of us. But how does it get there? Where does it come from? 

Actually, certain bacteria in our system can make histamine. In addition, certain opportunistic pathogens may make histamine as a way of distracting the immune system if you will. When the immune system is activated, stress and inflammation occur.

Since histamine alerts the immune system, an elevated level of histamine will result in a elevated level of inflammation in the body. 

These are the conditions in which these opportunistic pathogens can replicate because it will go unnoticed by the immune system. The immune system’s attention is elsewhere due to the histamine. 

Another source of histamine in our body is the immune system itself. Histamine is created in our body and stored in our mast cells. It is then released in response to a trigger stimulus. 

This trigger may be something in the environment that your body sees as a threat like pollen or pet dander. It may also be a food allergen that you consume. Whatever the trigger may be, it results in histamine release. 

Also, foods that are naturally high in histamine contribute to the overall histamine load in your body. 

High-Histamine Foods

Here are some foods that are high in histamine. 

  • Spinach
  • Fermented foods
  • Strawberries
  • Green tea
  • Egg plant
  • Alcohol
  • Avocado
  • Packaged, processed or smoked meats
  • Aged cheeses
  • Legumes
  • Citrus fruits

Other foods may actually stimulate the release of histamine in our bodies even though they are not high in histamine themselves. 

Histamine Releasing Foods

Here are some foods that may trigger the release of histamine.

  • Bananas
  • Nuts like walnuts, peanuts and cashews
  • Papaya
  • Chocolate
  • Beans
  • Tomatoes

Please keep in mind, these are not exhaustive lists but meant to provide examples.

What is Histamine Intolerance? 

So where does the “intolerance” to histamine come in? Generally, when our histamine levels are high, our body breaks it down with enzymes. 

The enzyme responsible in large part, for breakdown of histamine, is called diamine oxidase or DAO. Though, another enzyme called histamine n-methyltransferase, or HNMT, also helps break down histamine.

Histamine “intolerance” occurs in certain people who are unable to break histamine down. SO, to answer the big question, histamine intolerance is not necessarily an intolerance in a traditional sense like you would think of food intolerances. It is an OVERLOAD or too much histamine, resulting from the inability to break it down when levels get high. 

That said, some people may have a higher histamine load in their body to start with. This could be due to a diet high in high histamine foods as well as foods that cause histamine release. 

It could also be due to the state of the microbiome and whether it has a larger population of high histamine producers. 

It certainly could be from the way the immune system is functioning as well. There are different immune response processes and if the immune system is leaning toward the histamine producing route, this could result in high levels of histamine overall. 

DOA Enyzme

So back, to the “intolerance” issue. High histamine levels compound the problem, but generally, the true issue is that the histamine intolerant person is not breaking it down effectively. This results in their histamine levels STAYING high after becoming elevated. 

So why would someone not be able to break down histamine? Much of this has to do with the enzymes that are supposed to break it down.   

The DAO enzyme may not be functioning properly or in short supply compared to the amount of histamine in your body. Some people also have a DAO deficiency. 

One reason for this is leaky gut, due to the inflammation of the digestive tract lining that occurs with this. The gut lining is where much of our DAO enzyme is produced. If our gut lining is inflamed, this enzyme, as well as many others, could decrease in production. 

Inflammatory bowel disease like Crohn’s or Ulcerative Colitis, for the same reason, could impact DAO production and consequently histamine breakdown capability. If the person is not in remission and their gut is chronically inflamed, enzyme production will likely be low. 

Untreated celiac disease could also result in DAO deficiency from the inflammation that occurs with this as well. 

Also, some medications may interfere with DAO activity. In addition, some foods inhibit DAO function or production. These may include anti-emetics, blood pressure medications or antidepressants.

Histamine Intolerance Symptoms

Here are some common symptoms of histamine intolerance. 

  • Headaches
  • Flushing, especially in the head and neck area
  • Gastrointestinal symptoms
  • Nasal congestion or runny nose
  • Difficulty regulating body temperature
  • Hives 
  • Itching 
  • Dizziness
  • Tissue swelling
  • Irregular heart rate
  • Red, itchy eyes
  • Bloating

Managing Histamine Intolerance

Here are some ways to help manage histamine intolerance. 

First, we can make some dietary changes. We can attempt to lower the excess histamine in our bodies by reducing our dietary histamine.

Limiting our intake of foods with high histamine content as well as the foods that may contribute to histamine release, will of course, lower the overall histamine load in our body. 

Another management technique is to take a DAO supplement if the level of DAO is low. We can check DAO enzyme levels by doing a blood draw to know if this is the case. 

We can also change, or potentially stop in some cases, certain medications that may be interfering with DAO enzyme production or functionality. 

Treating Histamine Intolerance

It’s important to note the distinction between treatment and management. Treatment implies that something can be fixed and that is how I am using it here. The management techniques listed above are simply “managing” the condition – not necessarily fixing the true problem. 

The best way to approach seeking treatment for histamine intolerance is finding out what the root cause of it is. There are multiple different causes of histamine intolerance.

Some, as previously mentioned, include leaky gut related to inflammation. This inflammation could be due to inflammatory bowel disease or untreated celiac disease as just a few examples. 

Another condition that causes leaky gut and inflammation is something called small intestinal bacterial overgrowth, or SIBO for short. This condition not only causes inflammation but is also a displacement and overgrowth of certain bacteria in your small intestine. Some of the bacteria that tends to overgrow in this condition are high histamine producers as well. 

Once the underlying cause of histamine intolerance is addressed, histamine will likely be better managed in the body. 

For more information, check out these related posts:

As always, thanks for reading!