Histamine Facts

Here I have accumulated from the Web some facts about Histamine.

Histamine Intolerance

This is the hypothesis that symptoms can sometimes be caused by excessive histamine in the body, rather than by (or facilitating) reaction to specific allergens; and that, in such cases, Symptoms can be avoided by controlling the amount of free histamine in the body. Different people may have different levels of tolerance of histamine.

Histamine Poisoning

Sometimes the level of histamine in food can be so high that "normal healthy people" (i.e., people without any allergy) can be affected. Histamine poisoning was previously called Scombroid Poisoning because it was exclusively associated with scombroid fish (i.e., oily fish such as mackerel, tuna and salmon). When people had similar symptoms after eating cheese, they put it down to allergy (whereas with fish they correctly put it down to a type of food poisoning).

Histamine Functions

Histamine is present in all cells of the body and constantly active. Scientist have ascertained that it carries out at least 23 different functions. These can be divided into three areas: Brain and Central Nervous System (CNS), Immune System, and Digestive System. In the Brain, it is a neuro-transmitter associated with arousal and wakefulness. If histamine is not firing in the brain, we are asleep or in a coma. In the immune system, it triggers inflammation of various types. Histamine is usually released by Mast Cells, when its action is required; it then combines with a histamine-receptor, prompting some function, and is then immediately neutralised by an enzyme when this job is done. There are two main enzymes that neutralise histamine: N-methyltransferase (HMT) in the CNS and Diamine Oxidase (DAO) in the Digestive System. If the histamine is not neutralised by an enzyme, it sails freely through the blood ready to kick off uncalled-for inflammation at any time. Usually, inflammation happens at a single location, but when it is generalised throughout the body, we have the dangerous situation of anaphylaxis.


Medical anti-histamines prevent Histamine from binding with a Histamine-Receptor, thus avoiding the inflammation. They do not zap the Histamine, which continues to sail through the blood. For this reason, sufferers  often find that their use of anti-histamines increases over time. The answer to this problem is to take steps to reduce the level of Histamine in the body.

Dead Meat

At the moment when an animal dies, its flesh is histamine-free. However, bacteria present in and on the surface of the flesh, immediately start to decompose the meat. Some of these bacteria convert the amino acid, Histidine, into Histamine. If not checked, the level of Histamine in the meat can double every 20 minutes. Histamine is odourless, and meat that has excessive histamine may not be smelly. Other bacteria cause the meat to putrefy, which gives it a rotten smell. 

The Histamine-creating bacteria are inactive below 7 degrees Centigrade. The bacteria that cause putrefaction are inactive below 10 degrees. It can happen, accordingly, if meat or fish is stored in a cool place, but above 7 degrees, that the Histamine can multiply, even though the meat is not visibly "going off."

The EU Regulation of Fish

In the EU, we are fortunate that food is strictly regulated. Fish must be kept in melting ice from the moment it is caught. The temperature of melting ice is Zero C. Fish kept in ice will not rise above 5 degrees, so it is safe from Histamine build-up. The danger points are at processing, when carelessness might cause it to be left exposed to a somewhat higher temperature, or in the retail outlet, where it might be inadequately covered by ice. If histamine build-up occurs, subsequent cooling, or cooking, will not "kill" the histamine, which, of course, is a chemical, not a bacterium.
See: Irish Fisheries Board on Management of Seafood.

Preserved  and Fermented Food

Preserved food, whether tinned, cured, smoked or fermented, usually contains much more histamine than Fresh Food. The process of fermentation of food usually builds up the level of histamine in the food.

Cold Meats

Cooked meat, if stored at above 7°, will continue to convert histidine into histamine. If meat is to be kept for another time, it should be returned to the fridge as soon as it cools. Cold meats in delicatessens will tend to be rich in histamine.

Dairy Products

Fresh milk and cream is histamine free, as is butter, unless rancid. Yogurt can be rich in histamine or not, depending on the particular culture used. Mature cheese is rich in histamine, and can be so rich as to cause Histamine Poisoning.

Dry-aged Meat

Many web sites declare that well-hung meat has to be avoided on a histamine-restricted diet. This appears to be incorrect. Steak dry-aged for 28 days or more is always kept in a highly-controlled environment. It is carefully kept between 1 and 3 degrees C (as well as at a controlled humidity so as to  preserve flavour), so the prospect of Histamine developing is minimised. Meat informally butchered is more open to histamine contamination.

Carbohydrate Basis of Histamine Intolerance

Some scientists suggest that excessive consumption of carbohydrates, and the consequent activity of the Insulin gland, is the basic cause of the modern increase in Histamine Intolerance and allergies. (See: Alison Vickery on The Histamine, Mast-Cell Activation and Blood Sugar Connection).

Floyd H Chilton has carried out research that shows that excessive consumption of Omega 6 oils is also a major contributor. Omega Oils do not contain Histamine, but trigger the Mast Cells to release Histamine. In the case of Omega 3 Oils, they also contain the mechanism to degrade the Histamine, so cause no problem. Omega 6 Oils, however, do not contain this mechanism and, therefore, cause inflammation. Vegetable Oils and food preserved in oil, Dr Chilton found to contain excessive Omega 6.

The Scientific Basis of Histamine Intolerance

The hypothesis of Histamine Intolerance is supported by widespread anecdotal evidence. However, because histamine is actively present throughout the body and performs multiple functions, it has not been possible to provide scientific proof or conclusive tests for Histamine Intolerance

Cause of Histamine Excess

Usually, when it has carried out its physiological function, histamine is immediately de-activated by one of two enzymes, histamine-N-methyltransferase (HNMT) or diamine oxidase,(DAO). Excessive build-up of histamine can be caused by:
  1. Real Allergic Reaction;
  2. Mast-cell Disease: Excessive release of histamine by Mast Cells;
  3. Creation of Histamine by bacteria in the human gut;
  4. Excessive histamine in food, or
  5. Failure of a histamine-deactivating enzyme, (usually DAO).


This is a type of Schizophrenia associated with elevated levels of histamine in the blood. It has been found that the histamine in such cases can be reduced and the disease controlled by giving high doses of Vitamin C and Vitamin B3 (both Niacinamide and Niacin).

Vitamins C and B3

The scientific research on Histadelia seems to confirm the widespread belief that Vitamin C and Vitamine B3 (Niacin) can be used to reduce the level of Histamine in the blood. Interestingly it found that both Flush and Non-flush B3 should be used in concert.

Fruit and Vegetables

Fresh food usually contains little, if any, histamine, but the level builds up as the food matures, ages,  over-ripens, goes stale or spoils. Fruit should be stored in a cool place and eaten while firm. Soft or spoiled fruit should be discarded.

Tomatoes are often listed as histamine-rich foods. Bright firm examples contain less histamine than soft dark examples.

Strawberries are also listed as histamine-rich; again eat while firm and bright and discard if soft. Histamine can often be found in jams made from over-ripe fruit.

Levels of tolerance

Levels of tolerance of histamine in food vary, because histamine intolerance can have many different causes. In general, fresh food contains less histamine than stale, preserved, or over-ripe food. A person must find, by experiment, what foods to avoid. Some sites give very extensive lists of histamine-rich foods; but for many persons the "eat fresh," is a sufficient guideline.

Cheese and Red Wine

A survey of people who believe they are histamine intolerant found that the foods most often faulted as causing symptoms are cheese and red wine. Cheese can, indeed, be very rich in histamine. Scientists, however, have ascertained that "Red Wine Headache," is not caused by histamine, but by other chemicals  released by Mast Cells. A person who is histamine-intolerant can, then, be tolerant of red wine.

Histamine and Niacin Flush

Some authors say that one can test one's histamine tolerance by taking Niacin. If 50 mg of Niacin causes a flush, they say, this indicates a high level of histamine in the body, whereas, if it takes 200 mg, then one is "normal." This appears to be incorrect, because, again, scientists have found that the Niacin Flush is not  caused by histamine, but by other chemicals.

Avoidance of Excess histamine in the diet

  • Eat fresh rather than preserved food;
  • Avoid mature cheese; (this does not apply to full-fat cheese bearing a label to "keep refrigerated and eat within three days of opening");
  • Avoid tinned, smoked, cured, fermented and pickled food. There is some debate over whether salted food, as such, is included in the exclusion list, and whether cooked ham is the same as cured ham or is a fresh food;
  • Avoid minced meat, since the greater surface area can stimulate histamine production;
  • Eat fresh wild salmon and tuna, and other fish and shell-fish, if kept at all times below 5°;
  • Avoid farmed salmon, which can be too rich in omega 6 oils; (Floyd Chilton's book investigating this found that farmed salmon are fed on sunflower seeds; his findings may not refer to Irish farmed salmon, which are fed on off-cuts of fish and supervised by the Fisheries Board);
  • Always keep meat and fish in the fridge and below 5°;
  • Eat fruit when fresh and firm; discard if soft;
  • Eat tomatoes when bright and firm; discard when soft and dark;
  • Eat vegetables when fresh;
  • Eat cream and butter; avoid mature cheese;
  • Avoid yogurt, unless certain that its culture is anti-histamine rather than pro-histamine;
  • If necessary, try a more restrictive and supervised diet.

Controlling DAO

One cause of histamine build-up is failure of the body to produce sufficient of the DAO enzyme to keep it under control. This may be due to an imbalance of gut bacteria. It can also be due to excessive insulin in the system due to excessive digestion of carbohydrate. The gut situation can often be improved by cutting down on carbs and increasing fats, such as cream, butter, eggs, avocado and olive oil. Chicory drink to replace an ocasional coffee can be used to build up friendly gut bacteria. Intermittent fasting (skipping breakfast) can be used to allow the tummy to rest and to  build up its supply of good bacteria, DAO and other good content.

Daosin is a manufactured version of DAO and is taken by many to control their Histamine. Its manufacturer carried out research that shows that 60% of people who believe they are histamine-intolerant are self-diagnosed and that less than 10% take the enzyme. Clearly many people can avoid symptoms by diet alone.

Other Causes

"Histamine Intolerance" can explain some allergy-type symptoms. There are, of course, many other diseases that can be the cause.

My Case

I explored my own experience here: Histamine Intolerance

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