Histamine intolerance is when you have high histamine levels, which can result in allergy-like symptoms. But what does your gut have to do with it?
Content Outline
Introduction
From the smallest component to the largest, the human body is a complex mass of biological chemicals. Each of these chemicals has a specific role to perform, which is directed and regulated in response to or in interaction with another biological chemical.
The processes that take place have to be regulated to be carried out as required and are integral to your continued good health. However, if there is dysregulation anywhere in the chain of response, these responses can become confusing and lead to a specific role that should protect us from actually presenting a threat and even cause harm.
In this article, we will look at histamine, a compound produced by a specific type of white blood cell, the mast cell, that plays a crucial role in immunity. From allergies, migraines, and even digestive complaints, the gut microbiome and its interplay with histamine could be implicated. Why? Because if your gut health is compromised in any way, it can lead to an increased production of histamine, causing a range of uncomfortable and unpleasant symptoms. Here, we look at the relationship between your gut and histamine, investigate the common triggers for histamine intolerance, and provide tips to reset your gut and improve your histamine tolerance.
What is histamine?
Histamine, in its simplest form, is a chemical messenger for the immune system and has important roles in the body’s inflammatory response, digestion, and even your sleep-wake cycle. It has several functions, perhaps the most well-known being its role in causing allergic and anaphylactic symptoms [1].
Immune and inflammatory responses
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Allergic reactions: Histamine is best known for its central role in immediate allergic and anaphylactic reactions. It is released from mast cells and basophils upon exposure to allergens. This process causes symptoms such as itching, sneezing, a runny nose, and facial swelling.
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Vascular regulation: It causes widening of blood vessels and increases vascular permeability, allowing our immune cells to move easily through the bloodstream to the injury or infection site.
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Modulation of immune cells: Histamine significantly influences the function of many immune cells, including eosinophils, neutrophils, T cells, and dendritic cells, which are integral to both innate and adaptive immune responses.
Neurological functions
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Sleep-Wake cycle: In the brain, Histamine acts as a neurotransmitter, helping you to feel awake and ready to go about your daily tasks. Antihistamines block this process, which is what causes drowsiness.
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Cognitive function: It plays an important role in neurological functioning, including memory, learning, and attention.
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Pain perception: Through distinct effects on the central versus the peripheral nervous system, histamine is involved in the sensation of pain.
Gastrointestinal and Other Bodily Functions
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Gastric acid secretion: Histamine is essential for our digestive system, stimulating the release of hydrochloric acid by the parietal cells in the stomach, which is essential for digestion.
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Smooth muscle contraction: Histamine causes the contraction of smooth muscles in the lungs, uterus, and intestines. This can lead to asthma and even diarrhea relating to food allergies.
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Wound healing: Histamine aids to our wounds healing. This is done by the macrophages and the forming of new blood vessels.
Histamine is also involved in regulating food intake, our body temperature, and partly in sexual function and the regulation of our hormones.
It is clear that histamine is important for the proper function of the immune system and other processes throughout the body, but if it becomes imbalanced, it can contribute to health issues. For example, high levels of circulating histamine or not being able to break it down properly can lead to histamine intolerance, manifesting itself in several uncomfortable and unpleasant ways.
What is histamine intolerance?
As well as your body producing histamine in response to an allergen, it’s also naturally present in many common foods, especially fermented, aged, and processed foods, like wine and cheese, while some foods stimulate the body to release histamine, like shellfish, tomatoes, and spinach.
Some people are unable to break down histamine in their digestive system because an enzyme which breaks down histamine in the gut, diamine oxidase (DAO), is not working properly [2]. So, when DAO levels are low, histamine levels can accumulate, resulting in allergy-like symptoms.
Symptoms of histamine intolerance
Histamine intolerance can present in many ways. This can actually make it difficult to diagnose because it might cause symptoms that are mistaken for an allergy, like:
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itching
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hives
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swelling
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facial flushing
Due to the multiple processes that histamine is involved with, histamine intolerance symptoms can affect several areas in the body, including:
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Respiratory: sneezing, shortness of breath, sneezing, runny nose, blocked nose, wheezing, cough
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Gastrointestinal: abdominal cramping, bloating, diarrhea, nausea, constipation, acid reflux
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Cardiovascular and neurological: fatigue, dizziness, headaches, panic attacks, anxiety, palpitations, irregular heartbeat, low blood pressure, confusion, problems sleeping
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Other symptoms: fluid retention, joint pains, painful and heavy periods, tinnitus
A 2019 study found that bloating was the most common symptom of histamine intolerance, affecting 92% of people. Almost 97% of people experience at least 3 symptoms of histamine intolerance at once, with the average person experiencing 11 symptoms in total [3]. This study highlights the wide variability in histamine intolerance symptoms and why it can be challenging to distinguish from other conditions, making it difficult to diagnose.
What is DAO?
Diamine oxidase, or DAO, is an enzyme that is responsible for helping the body break down histamine. It works within the digestive tract to neutralise histamine before it enters the blood, acting as a defence mechanism for the intestinal mucosal layer [4]. DAO breaks down the histamine that’s naturally present in food or produced by your gut bacteria before it triggers allergy symptoms.
How the gut microbiome influences histamine levels
DAO activity is dependent on gut health, particularly how well your gut lining is functioning. If your gut barrier is compromised for any reason, like chronic inflammation or an infection, your DAO levels can drop, with DAO deficiency being a major factor in the development of histamine intolerance [5].
That’s not all – more recent research is suggesting that changes in the gut microbiome could also result in histamine intolerance [6]. For example, lots of gut microbes produce histamine, including:
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Enterococcus faecalis
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Bifidobacterium pseudocatenulatum
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Lactobacillus gasseri
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Escherichia coli
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Morganella morganii
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Proteus mirabilis
So, having a higher abundance of histamine-producers in the gut could lead to histamine intolerance. Schink and Co found that individuals with histamine intolerance have a 5.4% increase in Proteobacteria and a significantly reduced alpha-diversity (a measure of species diversity within a specified location, in this case, the colon). Healthy individuals had a higher abundance of Bifidobacteriaceae (think Bifidobacteria), whereas those with histamine intolerance had the lowest levels. The researchers concluded that dysbiosis and gut barrier dysfunction play a role in histamine intolerance and may lead to chronic disease [7].
Similarly, a 2022 study found that dysbiosis in the gut was also present in histamine-intolerant individuals, and compared to healthy controls had lower abundances of health-promoting microbes, including Faecalibacterium prausnitzii (Fig. 1). They also had higher numbers of histamine-producing bacteria, such as Proteus mirabilis and E. coli (Fig. 2), favouring an accumulation of histamine in the gut, which will find its way into circulation, even in people who do not have a DAO deficiency [8].
Figure 1. Histamine-intolerant individuals have a lower abundance of healthy bacteria, such as F. prausnitzii, compared to healthy controls.
Figure 2. The relative abundance of histamine-producing bacteria is greater in histamine-intolerant individuals compared to controls.
5 ways to strengthen your gut and improve histamine tolerance
Thankfully, there are ways you can reduce histamine intolerance symptoms. One of the key ways to do this is to address your gut health and support your gut microbiome through healthy diet changes, including adding prebiotic-rich foods and probiotics, and avoiding histamine-rich foods.
Here are some of the things you can do:
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Avoid or limit histamine-rich foods –limiting your intake of foods that naturally contain histamine can help to alleviate intolerance symptoms. Foods include aged cheeses, fermented foods, processed meat, and alcohol.
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Add prebiotics and probiotics to your diet – prebiotic-rich foods, like apples, garlic, onions, asparagus, oats, and legumes, help to nourish your microbiota, while probiotics can help to bolster your health-promoting bacterial communities.
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Get some regular exercise – regular physical activity increases the number of beneficial bacteria species, improves diversity, and helps to bolster commensal species, all of which strengthen gut health [9].
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Prioritize sleep – histamine has important roles in the sleep-wake cycle, so getting good and adequate sleep can help regulate the immune system and keep histamine levels balanced [10].
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Strengthen your gut barrier – resistant starch has been shown to reduce intestinal permeability markers, increase Akkermansia muciniphila abundance, and reduce blood histamine levels [11]. Choose a high-quality Akkermansia supplement to help bolster your gut lining.
Summary
Histamine intolerance occurs when there is an imbalance between accumulated histamine and the enzymes, such as DAO, that break it down, leading to allergy-like symptoms. It’s often a sign of an imbalanced gut, either due to an overgrowth of histamine-producing bacteria or a damaged gut lining, but making some small changes to your diet and prioritising your gut health can help keep histamine intolerance symptoms at bay.
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Written by: Leanne Edermaniger Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome.
