A deficiency or low activity of the enzyme diamine oxidase (DAO) can lead to altered dietary histamine metabolism. Its causes are very diverse and may be due to genetic, pharmacological or even pathological factors.
In this post we will explore more about this enzyme and its consequences for the body. We will also explain what the DAO test consists of and how it can help physicians when treating cases of this type.
What is DAO deficiency?
Do you ever remember eating a particular food and feeling a headache, nausea or itching the next day? If this has happened to you, it was probably due to a DAO deficiency. This enzyme, known as diamine oxidasehas the task of degrading histamine, an active compound. Its mission is very important, because if there is a higher than normal amount of this compound in our organism, it could damage it. and cause adverse effects.
DAO is one of the many digestive enzymes responsible for degrading nutrients and preparing them for intestinal absorption. In this case, this enzyme metabolizes histamine. You may experience a blockage for different reasons. This ‘malfunctioning’ of the enzyme causes histamine not to degrade as it should and accumulate in the body.
If a DAO deficiency is observed in a person, it means that there is not enough of this enzyme in the intestine. There is an imbalance between ingested and released histamine. This accumulates and adverse effects begin to appear. It is important to note that the symptoms do not appear as soon as foods rich in histamine are ingested, but have to accumulate in the blood.
What is histamine?
To understand the enzyme and the DAO test, we first need to explain what histamine is. This molecule derived from an amino acid (histidine) has many physiological functions related to circulation, capillary permeability, immediate hypersensitivity, allergic processes, etc. The main source of this molecule in the body is the organism itself (it produces it) and the second is food. Histamine from both sources is degraded upon passage through the intestinal mucosa by the enzyme diamine oxidase (DAO).
Normally, the presence of biogenic amines (or histamine) in food is attributed to some bacteria that degrade the proteins of the raw material. This study suggests that they could be the acid lactic acid bacteria used to obtain fermented foods. Contaminated food can also suffer from the presence of these amines. During fermentation, proteins are degraded to free amino acids. Thereafter, some are decarboxylated to form biogenic amines. Histamine is stored in some cells (basophils and mast cells). which, over time and depending on various circumstances, is released into the blood.
Although the first way of obtaining histamine is completely regulated, the second way depends on the individual and the food he/she eats. If any alteration in metabolism appears and blood histamine concentrations are not maintained in the range of 50 to 70 mg/L, the free circulation of this amine in high concentrations can produce migraine, fibromyalgia, asthenia and/or atopy.
Causes of the deficit
As mentioned above, the causes of DAO deficiency can be due to pharmacological and pathological factors, although the main cause is genetic. This is why migraine was thought to be hereditary, but what was actually inherited was the enzyme deficiency. There are several causes of such a decline:
- Genetic alteration, the most common factor in the deficit.
- Common medications (such as painkillers, antihistamines, antidepressants, antihypertensives, diuretics and antibiotics) that block the activity of the enzyme.
- Drinking alcohol to excess. Ethanol is a potent inhibitor of the oxidative activity of the DAO enzyme.
- Inflammatory bowel diseases (Crohn’s disease, ulcerative colitis or coeliac disease).
People with DAO deficiency usually have one or more of the following symptoms:
- Migraine, headaches, dizziness (central nervous system).
- Irritable bowel syndrome, constipation, diarrhoea, satiety, stomach pain, vomiting (gastrointestinal).
- Urticaria, atopy and psoriasis (dermatological).
- Fibromyalgia, muscular pain, chronic fatigue (muscular system).
- Osteopathic pain (bone system).
- Asthma, nasal congestion (respiratory).
- Hypotension, hypertension, arrhythmias (respiratory).
- Attention deficit and hyperactivity disorder (ADHD), related to childhood and adolescence.
Foods that can cause symptoms
Some foods contain more histamine than others. These are all fermented products in which acid lactic acid bacteria are involved:
- Matured cheeses (gouda, brie, Camembert, parmesan and roquefort, among others). They contain between 80 to 4500 mg per kilo of cheese.
- Fermented vegetables (sauerkraut).
- Sausages and other meat products. can contain up to 300 mg per kilo of feed.
- Fresh, salted and canned fish. Its value ranges from 1500 to 5000 mg per kilo.
- Wine and cider contain 5 to 130 mg per 100 ml.
- Beer. It provides between 2.8 and 13 mg. per 100 ml.
The Society of DAO Deficiency explains that citrus fruits (strawberries, pineapple, kiwi…), seafood, chocolate and tomato sauce release histamines from mast cells, which can help to balance levels. Pork, egg whites and mushrooms also help to stimulate release. Certain additives (sulphites, nitrites, monosodium glutamate, benzoate and yellow dyes) cause the cells to release histamine.
How is DAO deficiency diagnosed?
Initially, it is recommended that an enzyme activity study be carried out. In a later step, if the reasons for alterations in this enzyme are to be found, a genetic study of the DAO gene can be carried out to see if there are mutations that could affect its functionality.
To measure the activity of enzyme diamine oxidase in blood the DAO test is used. It may help us to discover if the origin of the symptoms lies in a histamine metabolism disorder present in certain foods rich in this substance. The test measures DAO enzyme activity and expresses the results in histamine degrading units (HDV). A histamine intolerance is moderate if it is at a value below 80 HDV, and high if the value is below 40.
To perform the test, a simple blood draw is required. Thanks to it, the medical specialist will be able to identify if the origin of the symptoms is in the diet. The DAO test is usually recommended for patients suffering from migraine or other vascular headaches, gastrointestinal, muscular, dermatological or skeletal disorders and chronic fatigue.
No special preparation is necessary to perform the DAO test, as it is a blood test. You should simply go to the consultation on an empty stomach (between eight and ten hours) and stop taking DAO inhibitor medication, if you are taking it.
To perform the genetic test, an EDTA-blood collection is required.
What is the risk of intoxication?
There is no consensus today on the minimum dose of histamine that can produce toxic effects in a common organism. In histamine intoxication, the levels contained in the food must be very high (more than 600 mg. per kilo).
However, intolerant people or those with a DAO deficiency, a much lower amount can trigger consequences. These threshold values range from 50 micrograms (a 125 ml. serving of wine) to 75 ml. If other amines appear in food or beverages, histamine toxicity may increase. In any case, although it is suspected that it may occur due to receptor competition in the intestine, it is not yet clear.
How to organize the diet in a DAO deficit?
If, after the DAO test, the doctor tells us that we do indeed have a deficiency, we must follow a diet not only low in histamine, but also adjust the combination of certain foods. You can find some guidelines here, but from AmbarLab we recommend that you only follow the orders of a qualified professional and do not organize a diet without prior consultation. The doctor knows your personal case and will know how to advise you appropriately.
Some professionals recommend eliminating foods containing more than 20 ml. of histamine per kilogram of product. Others, however, are more demanding: they consider consuming foods with a maximum of 1 mg per kilo.
The point on which everyone agrees is that fermented foods should be excluded. This list includes sausage, salami, chorizo, matured cheeses, canned fish and fresh dark-fleshed fish, among others. Certain vegetables (sauerkraut, fermented soybeans and spinach) are also not exempt from the ban.
Any fermented or distilled alcoholic beverages should also be withdrawn from the diet. It is even recommended not to combine some foods with these beverages, since they have a very high DAO inhibitory power. Although chard, tomatoes, olives, legumes and cereals contain histamine, their amounts are minimal, so they are not usually eliminated from the diet.Having the opinion and diagnosis of a professional and trained team is the only way to arrive at an adequate treatment for the patient. At AmbarLab has a wide variety of laboratory tests ,these include the DAO test, which can help you clarify any doubts or symptoms. If you cannot find the test you are looking for on our website, do not hesitate to contact us, we will be happy to create a project to suit you.
