What is histamine intolerance

Histamine degradation process

There are two main histamine metabolic pathways, i.e., the enzymes diamine oxidase (DAO) and histamine N-methyltransferase (HNMT), responsible for the breakdown of excess histamine.
The DAO enzyme contains copper, found mainly in the small intestine, liver, and white blood cells, and is produced in large quantities by the placenta.

Its cofactors are 6-hydroxydopa, pyridoxal phosphate (vitamin B6), and vitamin C.DAO degrades extracellular histamine. DAO is produced primarily by the small intestine, ascending colon, placenta, and kidney. In the intestine, DAO activity gradually increases from the duodenum to the ileum, and the enzyme itself is found mainly in the intestinal wall.

Most of the histamine, primarily in the central nervous system, is broken down by the enzyme methyltransferase. HNMT can be synthesized intracellularly but can also enter the cell from the extracellular space and is responsible for inactivating intracellular histamine. Insufficient amounts of S-adenosyl methionine (SAM) are available in case of undermethylation, which can also cause histamine to build up in the blood.

Undermethylation may also be due to micronutrient deficiencies, such as the lack of magnesium, and the digestive system e.g., vitamin B12 deficiency due to stress.

Positive effects of histamine

Some foods containing histamine have an exceptionally high micronutrient content, and dietary intake also increases gastric acid levels, which are important for protein digestion, killing of otherwise histamine-producing pathogenic bacteria, and absorbing vitamin B12 and micronutrients in food.

It is no coincidence that foods containing histamine are among the most popular delicacies, cf. e.g., Mediterranean food (Ripe cheeses, tomatoes, matured ham, red wine).

Other positive effects

– helps the production of stomach acid, thus the functioning of the stomach and digestion
– dilates blood vessels, lowers blood pressure
– regulates the sleep-wake cycle, makes you alert
– controls appetite, reduces weight
– improves learning skills and memory, increases intelligence
– regulates cell differentiation and growth
– regulates the neuroendocrine and immune systems
– accelerates wound healing

Negative effects of histamine

Other adverse effects are that it increases the tendency of smooth muscle tissue (gastrointestinal tract, lungs, uterus), dilates blood vessels (redness, itching, edema, drop in blood pressure), and increases the permeability of blood vessel walls.

The forms of symptom formation associated with histamine metabolism are not always clearly distinguishable and, in some cases, are referred to as histamine intolerance or mast cell activation syndrome (MCAS).

There is a significant overlap between the three problems in terms of both symptoms and causes, and thus the path to living without symptoms is similar.

Sources of histamine

• The downsides of histamine appear when the total intake and production of histamine significantly exceeds the histamine-degrading capacity of DAO and methyltransferase enzymes.

  • Histamine can be formed by the breakdown processes carried out by bacteria, e.g., during fermentation.
  • The histamine content of fresh food and meat increases rapidly during storage.
  • The intestinal flora also produces histamine in large quantities when certain bacteria settle in the intestinal tract.
  • Histamine is released in the body under stress, most notably at high cortisol levels, by mast cells, basophilic white blood cells, lymphocytes, neurons, and gastric mucosal cells. It also plays a significant role in the functioning of the digestive, nervous, and immune systems.

So how does excess histamine develop in the body?

• Foods containing histamine
• In case of dysregulation of mast cells
• From mental/emotional stress
• From physical stress – overtraining is also included
• By taking certain medications
• As a result of inflammatory processes: inflammation of the intestinal tract (e.g. SIBO) and damage to the intestinal mucosa are among the primary causes, as the intestinal wall is unable to produce DAO.

Histamine ingested with food

Histamine from the diet first encounters the intestinal epithelium in the body where its breakdown begins. Therefore, although HNMT is also present in the gastrointestinal tract, the higher presence of DAO plays a major role in protecting the body against externally occurring histamine, whether from ingested food or histamine produced by the intestinal microbiota.

Histamine is present in a wide range of foods in highly variable concentrations. The main cause of histamine formation in foods is the type of histidine produced by enzymes of bacterial origin. Many bacteria are responsible for microbial spoilage of food or fermentation processes that can produce histamine.

What foods cause symptoms?

Histamine is heat stable and cannot be neutralized during baking or cooking. Foods containing histamine:

Cheeses, sour milk products (cheeses made from raw milk and long-aged cheeses contain the most)

Red wine, sparkling wine, white wine, beer (Alcohol also blocks the action of the enzyme that breaks down histamine so that it can cause increased symptoms)

Dried, matured, smoked, canned fish and fish sauces, tuna (rich in histidine, from which a lot of histamines is quickly formed due to the large body during slow cooling), e.g., mackerel, sardines, herring, and salmon

Seafood only after long transport and storage (not fresh)

Dried, smoked, and processed meat products (e.g., salami), ham, sausages, bacon

Sauerkraut, pickles, and other pickles

Wine vinegar, balsamic vinegar

Emmental, camembert, Roquefort, gouda, cheddar, moldy and smoked cheeses

Mustard, ketchup, soy sauce

Chocolate, cocoa (tyramine, phenylethylamine), coffee, black tea

Bread and cakes made with yeast

Nuts, hazelnuts, sunflower seeds