Histamine Intolerance (HI)

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Histamine intolerance can occur when a person has an excess of histamine in the body and/or the body is unable to effectively break down histamine

It’s often described as a bucket that fills up little by little (from food, stress, pollen, etc) and once it overflows, you have symptoms. When your bucket is full/your histamine load is high, you often have triggers that you didn’t react to when your bucket was lower.

Histamine is important for various bodily functions and there are 4 types of histamine receptors located all over our bodies. This is also why histamine intolerance can cause so many symptoms. Your body makes histamine and has various pathways to break it down, such as the DAO enzyme or methylation. 

Histamine is found in varying quantities in food

Some foods are high in histamine, while other histamine liberators, meaning that they can trigger histamine release when you ingest them. The body normally breaks down histamine: for example, the DAO enzyme helps break down histamine in the gut. If your body isn’t breaking down your histamine as it normally should, due to low/impaired DAO production or something else, this contributes to your rising histamine load.

How to know if you have histamine intolerance?

I don’t know if there is any type of diagnostic criteria for this. Many people figure it out when they realize that have symptoms to high histamine foods, or that symptoms they have disappear when they take antihistamines.

Some contributing factors to histamine intolerance

• ingesting too many high histamine foods
  
  
• gut infections (some bacterias can produce histamine) or SIBO. Some probiotics strains also increase histamine in the gut.
  
  
• the interplay of hormones with histamine and DAO (estrogen can stimulate histamine release from mast cells and also inhibit DAO)
  
  
• having impairment of histamine breakdown pathways due to genetics or nutrient deficiencies
  
  
• mast cell activation syndrome (many people with MCAS have HI, but you don’t necessary have to have MCAS if you have histamine intolerance)

Some ways to help histamine intolerance

Low histamine diet

This can be very helpful for a lot of people to get symptoms more under control, but it’s important to be careful that you are meeting your nutritional needs. Unfortunately, when I started having MCAS symptoms 5 years ago, I had to severely restrict my diet because my reactions were so severe (including anaphylaxis), but over a few years I was able to work on contributing factors to my MCAS and slowly reintroduce a huge number of foods. This has been a huge win for me! I still need to avoid the highest histamine foods like dairy, fish, nuts, tomatoes, fermented foods, and a few others, but my eating situation is so much better than it was when I first got sick. Also, since my main histamine symptom is insomnia, I stopped drinking all tea and caffeinated drinks.

H1/H2 antihistamines

These can be helpful to help get your symptoms under control, although typically this isn’t a long term solution, as my understanding is that it’s not actually helping your body lower or break down histamine.

There are newer antihistamines that aren’t associated with dementia or scary health risks like some of the older generation ones are. I wish I had used antihistamines more when I was really struggling 5 years ago with an onslaught of symptoms, but I didn’t know for months that my symptoms were histamine related, and then when I did, I was feeling somewhat traumatized and scared to take them. Currently, I take them as a rescue when I have intolerable symptoms (insomnia or vertigo), and I take them every day as a preventative if I go on vacation (otherwise I would be incapacitated by MCAS with all the triggers that come from traveling).

Everyone needs to determine their comfort level with taking antihistamines. These are a medication so it’s important to speak to your doctor too.

Support pathways for histamine breakdown

If you know that you have low DAO or problems with your histamine methylation, there are vitamins and supplements you can take to support these pathways.

Look at your hormones

Especially if you are a women or person AFAB, estrogen can stimulate histamine, while progesterone can support DAO production. You may notice that depending on where you are in your menstrual cycle, you have higher or lower symptoms, or your histamine bucket fills faster or lower. Going on progesterone was a huge help for me. 

Genetic testing

I worked with a naturopath who suggested I do a DNA test from 23andMe, and then use the raw data to upload to Genetic Genie. This showed me SNPs in my DNA involving methylation and detoxification. From there, she recommended supplements to help me support those pathways.

I also know people have put their DNA raw data into ChatGPT and asked it to identify SNPs related to histamine and methylation. 

If you also have MCAS, take steps to manage it

More on my Managing MCAS page here