Bread with soft cheese - Food intolerance - aha! Swiss Allergy Centre - Info on allergies - © Image: Barbara Pheby / Fotolia

Food intolerance is a collective term for various non-allergic reactions to foods. Depending on the form of intolerance, up to 20% of the population are affected in Switzerland. Food intolerances cannot be detected by an allergy test. Milk sugar (lactose), fruit sugar (fructose), gluten and histamine are the most common triggers of intolerance, which is more common in adults than in children. Unlike food allergies, however, intolerances are not life-threatening.

Causes and triggers of a food intolerance

In a food intolerance, the body has partly or totally lost the ability to digest a certain substance – or it has never had that ability. The body does not form antibodies but reacts immediately to a food with symptoms. Small quantities of the food that triggers the symptoms can usually continue to be eaten without any consequences.

Symptoms of a food intolerance

The symptoms of a food intolerance can be many and varied. Most commonly these are general digestive complaints such as abdominal pains, flatulence, diarrhoea or constipation, queasiness. Other possible reactions: fatigue, irritability, skin rashes, headaches (migraine), circulatory problems, rheumatic complaints, etc. The symptoms often start insidiously. That is why it is not always easy to link these symptoms to a food intolerance.

Diagnosis and differential diagnosis

It can be difficult to prove so-called intolerances. History-taking forms the basis of the diagnostic investigation . Depending on what is suspected, tests (e.g. genetic test in the blood for suspected lactose intolerance or H2 breath test for suspected lactose intolerance or fructose malabsorption) may be performed to confirm the suspicion. If no test is available, an elimination diet (diagnostic diet) is followed. Food intolerances include the following groups:

  1. Malabsorption diseases: gluten intolerance (coeliac disease, sprue) and fructose intolerance (fructose malabsorption) come under this heading.
  2. Enzymatic intolerance: The cause is an enzyme deficiency or an enzyme defect, which results in the fact that certain food constituents cannot be (fully) digested. The following are known and inherited: hereditary fructose intolerance and galactose intolerance (galactosaemia). The following are acquired: lactose intolerance, histamine intolerance, sucrose intolerance, sorbitol intolerance, fructose malabsorption.
  3. Pharmacological food intolerances: Certain substances in foods are pharmacologically active and, if they are consumed in large quantities, can lead to symptoms of food intolerances (relative intolerance): biogenic amines such as histamine in tomatoes, red wine and mature cheese, phenylethylamine in chocolate, tyramine in mature cheese or chocolate, serotonin in bananas and nuts, glutamate (glutamate intolerance) and caffeine.
  4. Undefined intolerance reactions (pseudoallergic reactions to food additives): The symptoms are similar to those of an allergy. Undefined intolerance reactions are reactions to natural foodstuffs or certain additives such as salicylates, benzoate, colourings, emulsifiers, sulphites and taste enhancers.

Therapy and treatment

After diagnosis, those affected must eliminate the symptom-causing foods from their diet. In lactose, fructose and histamine intolerance the individual’s tolerance is ascertained in consultation with an HF/FH certified nutritionist. In coeliac disease, a strict gluten-free diet must be followed.
In terms of medication, the enzyme lactase can be taken as a tablet for lactose intolerance and the enzyme diamine oxidase for histamine intolerance.

Tips and tricks

  • If dishes containing lactose, fructose or histamine are eaten in small quantities and spread throughout the day, they are better tolerated.
  • Gluten-free and lactose-free products are available nowadays from major retailers.
  • When shopping, always read the ingredients list to make sure you can tolerate the food.

Editors: aha! Swiss Allergy Centre in co-operation with the Scientific Advisory Board. For prevalence figures, see source references.

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