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We are all familiar with Histamine and allergic reactions, particularly when related to hay fever or house dust mites for example. But this is only a small part of the story related to these chemicals.
Histamine is a neurotransmitter chemical which is essential for body functions. It is involved in the regulation of stomach (gastric) acid, the permeability of blood vessels, muscle contraction, and brain function. Histamine is also essential in defending the body against invasion by potentially disease-causing agents such as bacteria, viruses and other foreign bodies. This is part of the body’s normal inflammatory immune reaction. Everyone has a level of histamine that they tolerate without symptoms. Exceeding that level can result in symptoms which can be very similar to a whole raft of other issues. Skin rashes for example, which can also be from external sources.
Certain foods contain levels of histamine which can build up to the point that the controlling mechanisms in the body are overwhelmed.
The normal control mechanism in healthy people for histamine balance is by two enzymes, histamine N-methyl transferase (HMT) and in the intestine diamine oxidase (DAO), which breaks down the histamines. In general the system is in balance with some processes creating histamine and others destroying it. However we now know that a deficiency or overload of DAO can cause a wide array of symptoms and these symptoms can often mimic allergic reactions so that diagnosis becomes difficult.
An overload of histamine may cause a constellation of problems, including puffy eyes, rashes, hives, runny nose, swelling in the throat, itching, migraines, digestive upset (constipation and/or diarrhoea), nausea, and low blood pressure.
Histamines can also be absorbed from histamine-containing foods, and produced by bacteria in the gut. About 1% of people in this country will suffer from conditions which often feel like a regular allergy attack but the reactions can be quite severe and often apparently randomly related. One day you eat tomatoes and everything is fine, the next day -skin rashes appear.
Different foods cause histamine release at varying levels but with a balance of DAO, gut flora and other foods for example, negative reactions do not necessarily manifest every time.
There are also times when the DAO is naturally disrupted particularly in women during pregnancy, and during the normal menstrual cycle. Other elements like stress, processed foods, and some prescription drugs can also either release histamine or inhibit DAO. Very young children who are still developing their immune system can be severely effected by an imbalance. (This may explain the rise in eczema conditions in toddlers for example).
The biggest non-food source of histamines in most people’s bodies, though, is their gut flora. Some kinds of bacteria produce histamines, while others degrade them. The current tests for how good your DAO is functioning are generally considered to be inaccurate. The way forward if you think histamine might be the issue is through the gut. Amending the balance of bacteria from the food chain may be the answer.
Fresh foods are generally less prone to histamine content and refined, processed, fermented, stale and non-fresh products the opposite. (Fish gutted within half an hour are generally low level but histamine levels double every 20 mins if not gutted). So are you allergic to shell fish or the histamine build up in the fish after being caught?
Histamine could be a problem to many and because it is a complex area it needs a personal assessment rather than a simple cure. No two cases will be the same the tolerance levels and digestive capability vary considerably. If you think this could be a problem to you then a controlled elimination diet may be recommended.
The importance of gut flora in creating and destroying histamine can give rise to a sudden onset of histamine intolerance later in life, if you take antibiotics or make a drastic change to your diet. When the gut flora start growing back after this kind of trauma, the environment is ripe for bacterial overgrowth problems, and a predominance of histamine-producing bacteria might be just one of those issues.
To sum it all up, good gut health is just as important for histamine tolerance as it is for everything else. Unhealthy gut flora might even be able to create histamine intolerance problems in a person who would otherwise be completely healthy. Studies show that the probiotic bifidobacterium actually suppressed histamine release and in another study, Lactobacillus rhamnosus helped suppress histamine receptors.
(Ref :-National Centre for biotechnology information. www.ncbi.nlm.nih.gov/pubmed/18544899 )
Do remember that the vast majority of healthy people can metabolize the histamine found in foods without a problem, but it may explain some of the issues you encounter which are difficult to diagnose.