What is histamine intolerance?
Histamine intolerance (abbreviation: HIT, also referred to as histaminosis) is a food intolerance, which affects at least 1% of the population. An imbalance between intake/release and degradation of histamine results in an increased level of histamine in the body. The disease is mostly acquired; the congenital (genetically determined) type is rarer. Four out of five sufferers are women from the age of 40 years. HIT is not an allergy but a metabolic disorder (impaired degradation of histamine) without involvement of the immune system.
Normal histamine metabolism
Histamine is a substance, which is naturally produced in the body and regulates various functions (mediator, messenger, transmitter). In case of infections and allergic reactions, histamine puts the body's defense mechanisms on the alert. Histamine is also an inflammation mediator, a tissue hormone and neurotransmitter; it plays a role in the circadian rhythm, the bowel movements and many other processes. The body may produce histamine, store it in certain cell types and if necessary release it all at once.
Pathological mechanism in people suffering from histamine intolerance
Influenced by a wide range of factors, histamine may on the one hand be released from the body's own reservoirs and on the other be ingested. The body of a healthy subject is able to quickly degrade this histamine, so that it will normally not lead to any problems. If the amount of histamine in the body is - for whatever reason - too high for the body to eliminate, the histamine level increases too much. Food is usually the main source of histamine, and insufficient enzyme activity of diamine oxidase (DAO) and/or histamine-N-methyltransferase (HNMT) are the causes of an imbalance between the histamine intake/release and degradation.
The symptoms of histamine intolerance are similar to those of an allergy, food poisoning or the common cold. They usually occur in connection with food intake, either occasionally or chronically, so that it may be difficult for the people concerned to tie the symptoms to the foods ingested. There is a wide range of partly unspecific symptoms, which vary between individuals. Typical guiding symptoms are:
- Swelling of the nasal mucous membrane, runny nose, sneezing, expectoration, irritation of the throat, breathing troubles
- Digestive problems: diarrhea, abdominal pain, flatulence, heartburn
- Itching, rash, flush (particular in the face)
- Hot flashes, attack of sweating, impaired temperature sensation
- Tachycardia, allodromy, palpitation, drop in blood pressure
- Headache, migraine, dizziness
- Sleep disturbance, fatigue
- Nausea, vomiting
- Menstrual molimina
- Oedema (Swelling, water retention, i.e. swollen eyelids)
Unlike with allergies, where even traces of a substance may trigger a violent reaction, the intensity of HIT symptoms depends on the dose.
It is not possible to diagnose or exclude histamine intolerance based on symptoms. There is also no laboratory test that can diagnose HIT. The analytical determination of the enzyme level (DAO, HNMT) or the concentration of histamine and its metabolites in blood or urine may be included in the diagnosis, but do not constitute reliable indicators if they are considered out of context. Usually, the diagnosis at a consultation with a general practitioner is inconspicuous without any pathological findings, so that doctors often cannot relate to the suffering of their patients and do not see any need for further examinations. Many research findings are still new and not always known to the physicians. Often doctors would look for allergens as trigger when presented with histamine-related symptoms. They often simply do not consider the option, that there may be no trigger at all, but that an impaired degradation of histamine may be the cause of the histamine symptoms. That is the reasons why many cases remain undiscovered or are misdiagnosed or only identified months or years later. Typically, people suffering from HIT have spent a lot of time and energy, going from one doctor to the next, always undergoing costly examinations just to be eventually - out of a lack of understanding - declared perfectly healthy or labelled mentally ill (psychosomatic, hypochondriac, pathological attention seeker).
The only reliable method to diagnose HIT is an elimination diet lasting several weeks, where you consistently pass on all foods with histamine potential. The thoroughly instructed patients meticulously record all the symptoms and foods ingested. If the suspicion of histamine intolerance is confirmed, the symptoms will decline and conditions improve already within the first days. In case of doubt, a placebo-controlled provocation with encapsulated histamine may provide additional certainty. Subsequently, the patient determines his or her individual tolerance threshold by introducing the avoided foods one by one and by observing the reactions.
Histamine intolerance must be treated with a low-histamine diet. In addition, the therapy may be complemented with medicines and food supplements.A stress-free way of life has a positive effect. It is important for allergy sufferers to avoid allergens.
Histamine is a product of fermentation, maturation and putrefaction, which may be found in most foods in varying concentrations. Particularly products, which are easily perishable, are almost free of histamine when they are fresh, but may turn into veritable "histamine bombs" with increasing duration of storage. Particularly high concentrations of histamine may be measured in putrid fish and canned fish, sausage products and dried meat, mature cheeses, wine, champagne, beer and vinegar as well as in other fermented products. As histamine is heat and cold resistant, it cannot be removed from the foods by cooking or other methods.
Some foods do not contain histamine directly but certain substances called histamine liberators, which non-specifically release histamine, produced and stored by the body, and thus may also result in histamine-related symptoms. Other foods have the characteristic to block the enzymes that break down histamine or that facilitate the absorption of histamine in the intestines. That is why sufferers should avoid sauerkraut, spinach, tomatoes, aubergines, avocado, pulses (lentils, beans, soya), strawberries, raspberries, citrus fruits, bananas, pineapple, kiwi, pears, papaya, nuts, many sauces, condiments and spices, but also certain food additives. In principal, people affected by HIT should prepare their meals with fresh and preferably unprocessed products and consume them quickly or freeze them immediately.