Food intolerance

Do you often suffer from abdominal cramps or other digestive problems? Or do you always have coughing attacks, rashes or wheals? When the body reacts sensitively to food components, it can manifest itself in many different ways. That's why the diagnosis is often not that easy. But the opposite is also true: similar symptoms can be caused by different forms of food intolerance - which does not exactly simplify the cause search. To make matters worse, the terms are often not clearly defined or used differently.

Food intolerance: What does that mean?

Food intolerances (food intolerances, LMU) are the generic term for any unwanted, sometimes serious reactions that occur after eating food within minutes to a few days. These include complaints of food poisoning in healthy people, as well as symptoms caused by food constituents only in the case of particularly sensitive individuals, which is referred to as food hypersensitivity.

These are in turn based on various mechanisms: either processes in which the immune system is involved - as in food allergy (see below) and celiac disease - or those that run without immunological reactions, the so-called food intolerances (see below). Unfortunately, the term food intolerance is often equated with food intolerance - which does not exactly facilitate understanding.


The following terms should be distinguished in the context of food intolerances:

  • Food allergies (allergic food hypersensitivity): This hypersensitivity to a few or even many foods is one of the real allergies. The immune system reacts with a defense reaction to certain food components (especially eggs and other animal proteins, soybeans, nuts, seafood), which do not cause any reactions in healthy people.
  • Food intolerances (food intolerances): Again, certain food components are not tolerated, but in contrast to food allergy no immunological mechanism is detectable. Here again a distinction is made between two main groups:
  • Enzyme deficiency, the most common form of food intolerance, lacks or has limited protein that is needed for the digestion of certain nutritional components: in the intestine for its breakdown or in the blood for metabolism. Mostly the enzyme lactase is affected, which is needed to utilize the milk sugar (lactose) in the milk. If there is a lactase deficiency, the milk sugar is not split and thus no longer absorbed from the intestine (lactose intolerance, lactose intolerance). Rarely does a fructose intolerance occur.
  • The pseudoallergies are not easily distinguishable from the real allergies because they have the same symptoms and often the same triggers as these. The difference is that messenger substances such as histamine, which cause the discomfort, are not released by the activated immune system, but directly by the food. Common triggers are biogenic amines (for example in cheese, sauerkraut, spinach, tomatoes), salicylates (for example in fruits and vegetables, honey), coloring and preservatives.

Symptoms of food intolerance

As described above, there are several causes that can cause the same discomfort - and these in turn are not only in the gastrointestinal tract, but can also affect the respiratory system, the skin or - in pronounced cases - the cardiovascular system, Typical symptoms are:

  • Digestive tract: abdominal cramps, flatulence, nausea and vomiting, diarrhea (possibly bloody).
  • Skin: itchy, red spots or wheals; on the oral mucosa tingling, burning and swelling
  • Respiratory system: symptoms such as hay fever (stuffy noses, sneezing, watery eyes) or, due to swelling of the mucous membranes in the airways, respiratory distress as in asthma attack. In the worst case, it can lead to life-threatening allergic shock with rapidly increasing shortness of breath.

Allergic and non-allergic intolerances

The main difference between the allergic and non-allergic forms is that allergies are already triggered by very small amounts, while these are often still tolerated in intolerance reactions. Thus, a "milk allergic" can drink no milk, while someone who suffers from a lactose intolerance, can take quite small amounts without developing significant complaints.

Another distinguishing feature is that allergies (and pseudoallergies) occur at regular intervals (depending on the type of food allergy) (for example itching and tightness in the mouth after a few minutes, vomiting and diarrhea after one to two hours, in some allergy symptoms possibly even after one to two days), whereas in the case of enzyme deficiency, the reactions from person to person differ greatly in strength and time. This is also due to the fact that the function of the affected enzyme is individually disturbed to different degrees.

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