What is histamine intolerance?

What is histamine? 

Histamine is a biological molecule naturally synthesized in humans and animals. It is a so-called "messenger substance" that transmits and disseminates information between cells and plays an important physiological role in several body functions. Histamine is synthesized from histidine (an amino acid) and stored mainly in immune cells, mast cells and basophilic cells. In our body, it is mainly degraded by the enzyme diamine oxidase (DAO).

Histamine plays a role in the digestive system by stimulating the secretion of acidity necessary for digestion and sterilization of food. At the neurological level, it is involved in wakefulness and sleep.

Histamine exerts its effects via the activation of four histamine receptors: H1, H2, H3 and H4. 

H1 receptors can be found in almost the entire human body, H2 receptors are present in the stomach, H3 receptors in the lungs, intestine and the brain, and finally H4 receptors are located mainly in the brain. Histamine therefore acts on different organs (the brain, stomach, cardiovascular and respiratory systems, etc.), which may explain the diversity of signs when too much histamine is released.

What symptoms are caused by histamine intolerance? 

In case of an allergy, histamine is released en masse when the body is in contact with a substance to which it is sensitive. This causes the dilation of the small blood vessels (called capillaries) which in its turn leads to redness of the skin, and increases the release of water from the vessels, leading to edema, lowered blood pressure, increased heart rate and constriction of the bronchi.

In fact, due to a deficiency, dysfunction or altered activity of the enzyme diamine oxidase (DAO), some people cannot tolerate histamine. It has been estimated that 1% of the population is histamine intolerant.

The clinical picture of histamine intolerance includes many symptoms:

• Sudden redness of the face,
  

• Itching and redness on the body skin,
  

• Digestive disorders such as nausea, vomiting, diarrhea, abdominal pain,
  
• Drop in blood pressure, dizziness, tachycardia,
  
• Runny nose, chronic cold,
  
• Headache, migraine,
  
• Red eyes, swelling of the lips,
  
• In women: menstrual disorders.
  

These symptoms do not manifest themselves in the same way in everyone. Some people develop only some of the symptoms listed above.

The main trigger for such disorders is a high intake of histamine through the person's diet. In some people, the body can no longer sufficiently break down histamine that comes from food when there is not enough DAO.

Histamine is found in large quantities in both animal and plant products. The fermentation process influences the histamine content of food. The fresher the food, the better it is generally tolerated. 

Foods such as fermented cheeses, cold cuts, fish - especially when dried or smoked - fruit (especially strawberries), vegetables (tomatoes, spinach), sauerkraut, chocolate, beer, wine, etc. are rich in histamine. 

Moreover, histamine secretion is increased if a person is stressed. Prolonged stress can lead to a constant increase in histamine secretion.

Drugs or alcohol, even in small amounts, can temporarily block the activity of the enzyme diamine oxidase (DAO). It can also be impaired as a result of chronic inflammatory bowel disease (IBD) such as Crohn's disease or celiac disease. In the case of chronic disease, the enzyme deficiency is permanent.

How do you know if you are intolerant to histamine? 

Histamine intolerance is different from histamine allergy. However, it is often difficult to distinguish between the two conditions since the symptoms appear after eating certain foods and are almost identical.

Since the symptoms are not specific, certain food allergies and intolerances such as lactose intolerance, celiac disease or fructose malabsorption, or other disorders with similar symptoms, should be excluded in the first place.

Usually, the doctor will test for food intolerances and allergies. However, these tests do not detect histamine intolerance.

The diagnosis of histamine intolerance is initially clinical, through questioning. It is also possible to measure the activity of the enzyme diamine oxidase (DAO), which becomes disturbed in the case of histamine intolerance.

If histamine intolerance is suspected, a low-histamine diet can be prescribed for 10 to 14 days and should be supervised by a dietician or a nutritionist. Histamine intolerance is confirmed if the symptoms tend to improve during this period.

How can histamine intolerance be treated? 

Diet

Once histamine intolerance has been diagnosed, the most effective treatment is to avoid histamine-rich foods. However, this can be complicated as histamine is present in many foods and manufacturers are not obliged to indicate this on the packaging.

Many food lists are available on the Internet but few contain scientific measurement data on the histamine content. This is because the histamine content is influenced by several factors, such as the amount of food consumed and the individual tolerance level. 

Foods that have undergone a fermentation or ripening process should generally be avoided:

Source: nutritionbyerin.com

Medication 

In order to limit the symptoms that occur after a significant release of histamine, antihistamine drugs can be used. 

Histamine acts on cell receptors called H1 receptors. Anti-H1 antihistamines will take the place of histamine on these receptors and prevent its activation. 

There are two categories of antihistamines:

• First-generation anti-H1 drugs: they have many side effects such as drowsiness and fatigue,
  

• Second-generation anti-H1 drugs have few or no side effects.
  

Histamine intolerance cannot be cured by medication. However, antihistamine drugs can help relieve symptoms in the short term.