Histamine intolerance & Gut health
Recent research shows that there is a clear connection between histamine intolerance (HIT) and the gut microbiome. Here we review the effect of histamine on the intestinal mucosa, how a “leaky gut” can worsen histamine intolerance, and which specific microbes are involved in HIT.
This is part 2 of the series on Histamine. Also read part 1: Histamine Intolerance and part 3: Histamine and Irritable Bowel Syndrome (IBS) to gain a greater understanding of histamine and histamine intolerance.
What do we know today?
As described in the previous blog about Histamine Intolerance , histamine is a signaling molecule with a wide range of effects throughout the body. White blood cells (such as mast cells and basophils) as well as certain microbes produce histamine. Histamine is found in relatively high levels in the gastrointestinal tract, especially during inflammatory reactions . Low levels of the histamine-degrading enzyme DAO are a typical cause that leads to high levels of histamine in the body, thus causing symptoms of histamine intolerance (HIT).
The effect of histamine on the intestinal mucosa
The body's mucous membranes are in constant contact with food, microorganisms, and inhaled particles, and function as a defense against the outside world. The mucosal surfaces are also home to the microbiome , and have an important role in the health of the host, including in the functions of the immune system.
In the gut, the mucosa protects the intestinal wall from unwanted particles. If the mucosa is damaged and particles from food come into direct contact with the intestinal wall, it will irritate and cause an immune reaction. This will then cause mast cells to release histamine as a safety mechanism, which over time will result in high levels of histamine in the body . In addition, the DAO enzyme is constantly produced and released in the mucosa, ensuring the breakdown of histamine.
Dysbiosis, which is an imbalance between beneficial and harmful gut bacteria, can cause inflammation in the mucosa and damage the DAO-producing cells. This will result inreduced levels and function of DAO , and therefore poorer breakdown of histamine. The increased histamine levels in the body will therefore lead to HIT symptoms .
“Leaky gut” can affect histamine release
The intestinal wall is responsible for letting the good stuff like vitamins, minerals, etc. into the body and keeping the bad stuff like toxins, pathogens, and whole food particles out. Several barrier layers ensure this, as well as a layer of tightly packed epithelial cells . However, if this layer is defective, unwanted particles can leak through the intestinal wall into the bloodstream, resulting in a condition known as “leaky gut.”
Abnormal particles in the bloodstream are perceived as a threat by the immune system and cause an inflammatory response, which in turn leads to the release of histamine. With a “leaky gut” this inflammation becomes constant, which in turn results in higher histamine levels and HIT symptoms .
What is the connection between the gut and HIT?
An altered microbiome has been shown to be an important factor that can influence histamine intolerance. Dysbiosis and reduced alpha diversity are frequently observed in HIT patients. This is shown, among other things, by reduced levels of bacteria associated with gut health: Bifidobacteriaceae, Butyricimonas and Hespellia, as well as increased levels of the more harmful bacteria: Proteobacteria .
Additionally, HIT patients have been shown to have more histamine-producing bacteria in the gut, such as Escherichia coli , Lactobacillus vaginalis, and Morganella morganii . This can contribute to higher levels of histamine in the body, more inflammation, and is associated with inflammatory diseases like asthma and IBD .
Key messages
- Both a damaged mucosa and “leaky gut” can contribute to higher levels of histamine in the body and thus HIT symptoms.
- An altered microbiome (dysbiosis) and reduced alpha diversity have been observed in HIT patients, so restoring and maintaining a healthy gut microbiome is important to reduce the symptoms of HIT.
- Histamine intolerance and gut health is a relatively new and complicated field of research, and further studies are needed to gain more knowledge and draw further conclusions.
Author: Ingeborg Amble Holtmann
