Histamine is a biological substance naturally found in the body that affects the immune, digestive, and nervous systems. Under normal conditions, histamine regulates immune responses and can also play a role in allergic reactions. However, in some people, an excessive accumulation of histamine in the body can lead to a condition known as histamine intolerance. This occurs because the body cannot break down histamine sufficiently, resulting in symptoms similar to allergies.
What is Histamine?
Histamine is a chemical compound naturally present in the human body and plays roles in many biological processes. In the body, histamine is produced and stored by immune cells.
The primary function of histamine is to protect the body against foreign substances, microbes, or allergens and to initiate the immune response. When encountering an allergen or infection, histamine is released quickly, which can help dilate blood vessels, increase blood flow, and allow immune cells to reach the target area.
Sometimes when the defense mechanism works excessively or uncontrollably, various reactions may occur in the body. Symptoms such as runny nose, itchy eyes, skin flushing, nausea, or headache can arise when there is too much histamine in the body.
What Does Histamine Do?
Histamine is a versatile biological mediator involved in the functioning of many different systems in the body. Its primary function is to regulate the defensive response of the immune system and maintain physiological balance. Histamine also acts as a neurotransmitter, carrying messages from the body to the brain.
H1 (histamine receptors) are located in various parts of the body. H1 receptors can cause different allergic reactions in the body.
In addition to allergic reactions, H1 receptors can regulate the following conditions:
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Sleep cycles
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Food consumption
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Body temperature levels
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Memory
What is Histamine Intolerance?
Histamine intolerance occurs when the body cannot sufficiently break down the amount of histamine ingested. Although commonly known as histamine allergy, it is not actually an allergic disease, but a metabolic imbalance.
The body can break down histamine ingested through food or naturally formed, with the help of special enzymes. The most crucial part of this process is an enzyme called Diamine Oxidase (DAO). When the DAO enzyme functions inadequately or there is an excess histamine load, histamine accumulates in the blood. This leads to symptoms resembling allergic reactions.
What Are the Symptoms of Histamine Intolerance?
Symptoms of histamine intolerance usually develop within a few hours and can affect various organ systems. The severity of symptoms varies from person to person; sometimes, transient symptoms such as mild flushing and headaches are observed, while in other cases, stomach and respiratory system complaints may be more noticeable.
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Headaches and migraine attacks
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Attention deficit
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Insomnia and excessive fatigue
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Anxiety and restlessness
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Nasal congestion, runny nose, and sneezing
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Itchy and irritated throat
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Shortness of breath, cough, and chest tightness
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Nausea
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Abdominal pain
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Loss of appetite
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Low blood pressure or sudden blood pressure changes
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Itching, hives, or rash
Why Does Histamine Intolerance Occur?
Under normal conditions, histamine obtained from food or produced naturally in the body is broken down and inactivated by two enzymes called Diamine Oxidase (DAO) and Histamine-N-Methyltransferase (HNMT). However, when the activity of these enzymes decreases or the intake of histamine exceeds what the body can tolerate, histamine accumulates in the bloodstream. This imbalance presents itself with allergy-like symptoms but is independent of the immune system.
The most common causes of histamine intolerance:
Deficiency of the DAO (Diamine Oxidase) Enzyme
The cause of histamine intolerance is the deficiency or malfunction of the DAO enzyme. This enzyme is produced in the intestinal mucosa and is responsible for breaking down histamine ingested with food.
Conditions that can lead to a decrease in DAO activity:
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Genetic predisposition
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Long-term use of antibiotics or medications
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Poor nutrition
This situation can cause histamine to accumulate in the blood and intensify symptoms.
Excessive Consumption of Foods High in Histamine
Some foods contain histamine directly, while others increase histamine release. When consumed excessively, the histamine load increases, and the body cannot balance it:
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Fermented products (cheese, pickles, wine, beer, kefir)
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Processed meats (sausages, salami, pastrami)
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Types of fish (tuna, mackerel, sardines)
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Tomatoes, spinach, eggplant, avocado
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Chocolate, vinegar, soy sauce, shellfish
The Effect of Medications on the DAO Enzyme
Some medications can suppress the effectiveness of the DAO enzyme, slowing down histamine metabolism.
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Antidepressants
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Painkillers and anti-inflammatories
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Blood pressure medications
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Antihistamines
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Antibiotics
Imbalance in the Gut Flora
A significant portion of histamine is processed in the gut. Disturbance in the gut microbiota makes it difficult to break down histamine.
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Imbalance in probiotics
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Infections or chronic inflammation
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Long-term poor dietary habits can adversely affect this process.
Alcohol and Stress Factors
Alcohol suppresses the DAO enzyme and can slow the clearance of histamine from the blood. Stress can increase histamine release by altering cortisol balance in the body. When these two factors occur together, histamine intolerance symptoms such as facial flushing, headaches, and stomach discomfort can become more pronounced.
Hormonal Imbalances
In women, histamine activity increases during periods when estrogen levels are high.
Therefore, symptoms may be more intense in the premenstrual period, during pregnancy, or when using birth control pills. Estrogen's inhibitory effect on the DAO enzyme can facilitate histamine accumulation.
Which Foods Contain Histamine?
Histamine is naturally present in some foods, while others can increase histamine release in the body. Therefore, it is essential for individuals with histamine intolerance to be aware of which foods are rich in histamine in their dietary plan.
The histamine content depends on factors such as the freshness of the food, processing method, storage conditions, and fermentation duration. The histamine level is high in foods that are aged or fermented for a long time.
Foods High in Histamine That Should Not Be Consumed
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Varieties of aged cheese
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Processed meat products
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Tuna, mackerel, sardines, herring, anchovies
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Fermented foods
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Alcoholic beverages
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Tomatoes, eggplant, avocado
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Chocolate, cocoa, coffee, energy drinks
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Citrus
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Shellfish
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Nuts, walnuts, cashews
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Foods kept for a long time or reheated and consumed again
Low-Histamine Consumable Foods
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Freshly cooked meat
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Fresh fish
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Egg
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Rice, quinoa, oats
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Zucchini, carrots, broccoli, lettuce, cucumber, green beans
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Apples, pears, watermelon, melon, blueberries
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Olive oil, coconut oil
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Chamomile, rooibos, ginger tea
How is Histamine Intolerance Treated?
The primary aim in the treatment of histamine intolerance is to reduce the histamine load in the body and increase the effectiveness of the Diamine Oxidase (DAO) enzyme that breaks down histamine. Although there is no permanent treatment method, symptoms can be largely controlled through proper nutrition and lifestyle changes.
The first step in treatment is a low-histamine diet. Fermented, processed, or foods kept for a long time should be avoided; freshly prepared meats, vegetables, and fruits should be preferred. In some cases, DAO supplements recommended by a physician can help break down the histamine in foods.
Keeping the gut flora balanced is also important in the treatment process. Fibrous foods, probiotic supplements, and adequate water intake contribute to maintaining intestinal health and supporting histamine balance.
With an appropriate diet, lifestyle adjustments, and supportive treatments under a physician's supervision, histamine intolerance symptoms can be alleviated, and quality of life can be significantly improved.
Frequently Asked Questions
What is histamine allergy?
What is known as histamine allergy is actually histamine intolerance. In an allergy, the immune system overreacts to a substance, whereas in intolerance, histamine accumulates in the body and produces symptoms similar to an allergy. Therefore, histamine intolerance is not an allergy but a condition related to enzyme deficiency.
How is a histamine intolerance test conducted?
Tests measuring DAO enzyme levels and histamine amount in the blood can be applied for diagnosis. An elimination diet can also be used to observe symptoms by limiting the consumption of histamine-containing foods. Differential diagnosis can be made with allergy tests if necessary.
Can histamine intolerance be treated?
Symptoms can be reduced through a low-histamine diet, stress control, DAO supplements, and supporting intestinal health.
Who is more likely to experience histamine intolerance?
It is more common in women, especially during periods of hormonal changes; in those with digestive system diseases or who have an imbalanced gut flora.
