What is DAO deficiency and what are its consequences?

The DAO enzyme has an important role in the body. Its deficit can cause some symptoms. We meet them in this article.

Last update: 12 March, 2022

Has it ever happened to you that you eat something in particular and the next day you feel a headache, nausea or itching? Well, it is probably a deficiency of DAO or of the enzyme known as diamine oxidase. It is responsible for degrading histaminean active compound that in certain amounts could harm the body.

A malfunction of DAO or a chemical blockade of its action through drugs or alcohol can prevent the degradation of histamine. The excess of this amine in the blood comes from certain foods or from some cells where it is stored.

What is DAO deficiency?

Before explaining what DAO deficiency is, we must remember that digestive enzymes are responsible for breaking down nutrients and prepare them for intestinal absorption. One of them is DAO or diamine oxidase, which is responsible for metabolizing histamine.

DAO deficiency is a lack of the enzyme diamine oxidase in the intestine. When DAO is not present, an imbalance occurs between ingested and released histamine. In this way, the amine accumulates in the plasma and adverse effects appear.

The onset of symptoms is not immediately after eating foods rich in histamine. They appear later, from the sustained accumulation of that molecule in the blood.



What is histamine?

histamine is a non-protein nitrogenous molecule classified within the biogenic amines. These compounds are obtained from the transformation of some free amino acids, such as histidine.

Amines play an important role in the body’s defense against external agents. In the specific case of histamine, it is a mediator of allergic diseases, so the consumption of food with it can cause symptoms similar to those of allergic processes. And although they are often confused, they are not the same.

When DAO production is deficient, histamine is not degraded and passes directly into the blood. The increase in its concentration can cause diarrhea, hives and migraine.

Where does histamine originate?

In general, the presence of biogenic amines in food is attributed to some bacteria that degrade the proteins of the raw material. According to the Institute of Dairy Products of Asturias, these microorganisms may be the lactic acid bacteria that are used to obtain fermented foods.

However, biogenic amines can also be formed in contaminated food. Some authors describe the cheese reaction and the scombroid poisoning as forming processes in dark meat fish, for example.

Martucelli and other experts explain that during fermentation, proteins are broken down to free amino acids. From here, some are decarboxylated to form biogenic amines.

Histamine is stored in some cells such as basophils and mast cells. In the presence of an antigen, it is released into the blood.



Causes of DAO deficiency

There are several reasons that can cause a deficiency of the enzyme diamine oxidase:

  • Genetic alteration: this is considered the most common factor of DAO deficiency.
  • Pharmacological: Some common medications, such as painkillers, antihistamines, antidepressants, antihypertensives, diuretics, and antibiotics, block the activity of the enzyme.
  • Drink alcohol in excess: ethanol is a potent inhibitor of the oxidative activity of the enzyme DAO.
  • Inflammatory bowel diseases: such as Crohn’s disease, ulcerative colitis or celiac disease.
The genetic cause is the main responsible for the lack of the enzyme in humans.

Foods that contain histamine and can give symptoms

Within the foods that are sources of histamine we find all those fermented in which lactic acid bacteria are involved:

  • Ripened cheeses: As the goudathe brie, Camembert, Parmesan and Roquefort, among others. They contain between 80 to 4500 milligrams per kilogram of cheese.
  • Fermented vegetables: sauerkraut.
  • Sausages and other meat derivatives: They can contain up to 300 milligrams per kilo of food.
  • Fresh, salted and canned fish: They have a value that ranges between 1500 to 5000 milligrams per kilo.
  • Wine and cider: they contain from 5 to 130 milligrams per 100 milliliters.
  • Beer: provides between 2.8 to 13 milligrams per 100 milliliters.

According to International Society of DAO DeficiencyFoods that release histamines from mast cells include citrus fruits, strawberries, pineapple, kiwi, shellfish, chocolate, and tomato sauce. The consumption of pork, egg whites and mushrooms also stimulates this release.

Some additives, such as sulfites, nitrites, monosodium glutamate, benzoate and dyes from the yellow range are triggers for cells to release histamine.

Consequences of DAO deficiency

The consequences of DAO deficiency will depend on the accumulated histamine. In the magazine Food Chemistry point out that histamine and tyramine produce intoxication in different organs:

  • Central Nervous System: migraine, headache and dizziness.
  • Cardiovascular system: dilation of blood vessels, low blood pressure, headache and facial flushing.
  • Skin: eczema, dermatitis, urticaria.
  • Digestive system: irritable bowel, diarrhea, constipation, nausea, vomiting.
  • Muscles: sharp pains.
  • Woven bone: osteopathic pain.
  • Respiratory system: asthma.

What is the risk of poisoning?

As the literature indicates, there is still no consensus on the minimum dose of histamine that can produce toxic effects in the general population. In histamine intoxication, the levels contained in the food have to be very high, with more than 600 milligrams per kilo.

However, in people who are intolerant or deficient in DAO, much less can trigger symptoms. These threshold values ​​range from 50 micrograms (a 125-milliliter serving of wine) to 75 milligrams.

The presence of other amines in food or drink can increase the toxicity of histamine. Although it is not yet clear, it is suspected that it occurs due to receptor competition in the intestine.

The alcohol contained in wine, for example, increases the effects of histamine in people with DAO deficiency.

How should the diet be in a DAO deficiency?

Diets to treat a DAO deficiency should not be based only on being low in histamine, but it will also be necessary to adapt the combination of certain foods. The suggested guidelines are well documented.

some recommend eliminate foods that contain more than 20 milligrams of histamine per kilo of product. While others are more demanding and consider using foods with a maximum of 1 milligram per kilo.

The diet must exclude fermented foods. Among them the sausage, salami, chorizo, mature cheeses, canned fish or fresh fish with dark meat. Some vegetables, such as sauerkraut and fermented soybeans, should also be avoided.

Fermented or distilled alcoholic beverages should be removed from the diet. It is even recommended not to combine certain foods with these drinks due to their DAO inhibitory power.

Although trace amounts of histamine are reported in Swiss chard, tomatoes, olives, legumes, and cereals, this presence is occasional and is not eliminated from the diet. Spinach should be avoided.

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