Do you start itching when you eat cured meat? What about random headaches you can’t figure out? Or perhaps your tongue gets all swollen when you eat bananas?
If you’ve answered yes to any of these questions, let me assure you that it’s not ‘all in your head’: you could have a histamine intolerance. Or more precisely a ‘mast cell activation disorder’. I’ve experienced histamine intolerance first hand, which is why I wrote this article. So I know how annoying and troubling the symptoms can be.
But the good news is that you can get better. Read on to find out everything you need to know about histamine intolerance and what you can do to address the root cause of your symptoms.
What is histamine?
What comes to your mind when you think of histamine? Allergies and a stuffy nose during seasonal changes? Or perhaps the redness and painful swelling caused by a mosquito bite or a bee sting? Well, these symptoms occur due to the release of histamine, an organic nitrogen compound that causes an immediate inflammatory response.
Many of us see histamine as an irritating bad guy that causes allergies. But the truth is that histamine is a normal physiological response that acts as a red flag to alert the body of any potential attacker.
Moreover, histamine also works as a:
- Neurotransmitter which communicates important messages between the brain and various parts of the body.
- Component of stomach acid which helps the body extracts nutrients from the food you eat.
Immune system meets Invader – a real life story
The production of histamine is very complex but in a nutshell, here’s how that goes:
1. An invader (such as pollen, dust particles or an insect’s venom) enters the body.
2. The immune system encounters the invader and trigger mast cells, white blood cells that act as the sentinels of our innate immune system.
3. The mast cells quickly notify the body by releasing histamine from secretory granules (storage sacs).
4. The histamine produced triggers the release of other immune cells and also dilates capillaries – small blood vessels. This swelling makes the capillaries more permeable to those immune cells, allowing them to quickly find the invader and attack it.
5. Usually, once the invader has been ‘apprehended’, the body releases two main enzymes. These include namely histamine N-methyltransferase (HMT or HNMT) and diamine oxidase (DAO). HMT and DAO break down the histamine produced into N4-methylhistamine and imidazole acetaldehyde respectively. These reactions inactivate the histamine thus preventing its accumulation in the blood.
For most people, this usually marks the end of the story. However, as discussed below, for some individuals, histamine can be a much greater issue.
Histamine intolerance – Not your typical food intolerance
Let me start by saying that, just like ‘adrenal fatigue’, ‘histamine intolerance’ is a collection of symptoms and not a diagnosis. This is why many conventional practitioners will tell you that histamine intolerance does not exist.
A mast cell activation disorder (MCAD) is currently the most accurate diagnosis of what patients with ‘histamine intolerance’ are suffering from. However, since not many individuals know about MCAD, I’ll be using the term ‘histamine intolerance’ in this article.
As mentioned earlier, mast cells act as the guards of the immune system. Therefore, in an attempt to maintain a normal environment within the body, these cells react to changes in the environment or insults to the body. They do so by releasing molecules such as histamine. For optimal body function, we need these mast cells and the molecules they release. Besides their role in allergies, mast cells are involved in:
- The production of new blood cells
- Wound healing
- Immune tolerance development
- Maintenance of the blood-brain barrier function
- Protection against pathogens
However, in the case of MCAD, problems occur when these cells function abnormally, leading to histamine intolerance. MCAD has also been linked to:
- Skin conditions
- Irritable bowel syndrome (IBS)
- Depression and anxiety
- Alzheimer’s disease
- Male infertility
- Autoimmune disorders like rheumatoid arthritis
- Bladder pain syndrome
Why would someone have issues with histamine?
By now, you will have realized that the problem isn’t with the histamine. So why would histamine be so problematic for some individuals?
Well, based on current research, it appears that some individuals produce too much histamine whilst others are unable to break down histamine.
Why would a person make too much histamine?
1. Overactive mast cells (mast cell activation syndrome). This can be caused by:
– Toxicity of heavy metals like aluminum and mercury
– Infections or gut dysbiosis
– Chronic Inflammatory Response Syndrome (CIRS) – individuals who are particularly sensitive to molds, are more likely to be constantly activating their mast cells. That’s because these individuals would be less able to clear out mycotoxins (poisons released by toxic molds) from their bodies.
4. Mastocytosis, a rare genetic condition caused by an excess of genetically altered mast cells.
3. Too many gut bacteria that produce histamine.
Why would a person have trouble breaking down histamine?
Unfortunately, there are numerous possibilities. For instance, a person may suffer from:
- A deficiency of histamine N-methyltransferase (HMT or HNMT)
- Impaired efficiency of DAO due to genetic mutations in the DAO gene. These mutations are more common among Caucasians.
- Reduced activity of HMT due to micronutrient deficiencies which can affect the methylation pathway through which HMT deactivates histamine
- Low levels of bacteria that degrade histamine
- MTHFR mutation – No, it’s not a swear word (although it sure looks like one!): MTHFR actually stands for methylenetetrahydrofolate reductase. This involves a defect in the genes related to the methylation pathway. Individuals who are homozygous for MAO can be more sensitive to histamine. [A 23andMe gene profile run through Genetic Genie or MTHFR Support can help you determine this.]
Some individuals may also be deficient in diamine oxidase (DAO). This deficiency can be caused by:
- A genetic issue with DAO production (more common in people of Asian origin)
- Gluten intolerance
- Increased intestinal permeability (very common among individuals on a standard Western diet)
The following drugs can also interfere with DAO levels in the body:
- Non-steroidal anti-inflammatory drugs like aspirin or ibuprofen
- Antihistamines like Zyrtec, Allegra and Benadryl
- Histamine (H2) blockers like Tagamet, Zantac, Pepcid
- Antidepressants like Cymbalta, Effexor, Prozac, Zoloft
- Immune modulators like Plaquenil
- Antiarrhythmics like metoprolol
Why does the degree of histamine sensitivity vary so much?
That’s a question I get asked all the time. Some may say that a person suffering from poor health or poor lifestyle habits is more likely to be more histamine intolerant. While it is true that health status does determine sensitivity, the issue is much more complex.
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