Food allergy: A food allergy is an adverse reaction of the immune system to particular foods/ingredients. It occurs reproducibly and immediately (or with little delay only) on exposure to a given food. It is absent during avoidance. A food allergy can be diagnosed via a test (e.g. skin prick test) as certain reactions of the immune system (IgE-mediated, or T-cell-mediated) are identified in the test.

The most common food allergies, especially in children, are: cow´s milk, peanuts, eggs, tree nuts, wheat, and soy. In many children, these allergies outgrow between 1 – 5 years of age. In adults, the most common allergies are shellfish, peanut, tree nut, and fish. True food allergies are more common in children than in adults – but in general, there seems to be an increasing prevalence of food allergies.

The symptoms can vary widely, from disturbances in the gut, on the skin, or the respiratory system (e.g. itching/tingling of the lips, more severe: blistering, eye itching, redness and watering, respiratory compromise, abdominal pain, vomiting etc.)

Food intolerance: A food intolerance does not involve the immune system. The symptoms normally appear with a delay, and they can last for hours to days.

Food intolerances are more frequently reported than food allergies.

Up to now, most intolerances are harder to explain. In some of these, a known pathophysiological mechanism underlies the reaction (e.g. a deficiency of the enzyme lactase in lactose intolerance people), while in other food intolerances the mechanism is not understood yet.

The symptoms can include gastrointestinal upset, headaches, migraines, tiredness, muscle or mucle/joint-ache, mood changes.

A food elimination diet is often the best appropriate treatment.