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Useful facts on allergic and non-allergic food sensitivity (matvareoverfølsomhet)

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Allergic and non-allergic food sensitivity

What is food sensitivity?

Food sensitivity is sensitivity to the ingredients in food. In food allergy the body’s immune system is activated against the proteins from food, which are interpreted by the body as “dangerous” intruders. Even small traces of the food to which the individual is intolerant can be sufficient to trigger an allergic reaction. The reactions usually occur rapidly after ingestion of the foodstuffs and in some cases can be serious.

In other types of food sensitivity the immune system is not involved but the symptoms may be similar to those suffered in allergic reactions. The onset of symptoms is less rapid; they are less serious and are dependent on the quantity of food eaten. The term ’intolerance’ is often used to describe a food reaction, without this being demonstrated in laboratory tests. (There are many forms of food sensitivity or ’food intolerance’ – as it is often called.)

Incidence of food allergies

Among younger children, from 1 – 3 years old, 5-8% have reactions to food. In the remaining population, around 5% have food product allergies/intolerance, if pollen-related cross-reactivity is included. Many more are affected in their daily lives, where the problem has practical consequences for families and friends.

Common forms of food intolerance:

In small children, allergies to milk, egg, fish, nuts, shellfish and pulses (peas, peanuts, beans, soya and lentils) are most common. In particular, children with atopic eczema may have non-allergic sensitivity reactions to citrus fruits, strawberries and tomatoes. These reactions depend on the quantity of the substance eaten. Common symptoms are itching and flare-up of the eczema condition.

In older children and adults, allergies to nuts, peanuts, and shellfish are the most common. In addition, there is pollen-related cross-reactivity to some raw fruits and vegetables.

Wheat flour can bring on serious allergic reactions in children; however, this seldom occurs in this form in adults. Children and adults with irritable bowel condition can, however, experience increased bloating and stomach pains after consuming large amounts of wheat, rye and barley.

It is also possible to react to wheat, or other food products, only when consumption is followed by physical activity. This is a type of allergic reaction that can be difficult to diagnose.

Coeliac disease is an autoimmune disorder primarily affecting the small intestine, where gluten proteins in wheat, rye and barley cause inflammation of the intestinal walls. Coeliac disease is treated by adopting a lifelong gluten-free diet.

Lactose intolerance means that the gut mucosa has reduced ability to break down milk sugar (lactose). Symptoms of lactose intolerance do not normally occur before the ages of 4 to 10. Lactose intolerance is not dangerous; however, it causes stomach pains, bloating and diarrhoea if large amounts of lactose are consumed.


Reactions to food allergies and intolerance can vary from mild symptoms, which subside after a short period, to more serious, and sometimes life-threatening, symptoms. Tingling/itching in the mouth and throat and swelling of the mucosa are termed oral allergy syndrome and are typical in cross-reactivity to foods, such as frequently experienced by individuals with pollen allergy.

Typical gut and stomach symptoms are bloated stomach, pain, diarrhoea, nausea and vomiting. Skin symptoms such as urticaria, exacerbation of eczema and itching are also common, particularly in small children. Allergic shock (anaphylaxis) is rare, but is extremely serious and requires urgent treatment. It is characterised by swelling of the throat, breathing problems, often vomiting, and can progress to a drop in blood pressure and loss of consciousness.

How is it diagnosed?

Skin prick test and blood tests are the most common methods. These alone are not sufficient to establish a diagnosis; these must in the majority of cases be combined with food tests in order to confirm the diagnosis. It is essential that important foods are not excluded from the diet without a clear diagnosis. This applies in particular to suspected coeliac disease, where a diagnosis is almost impossible to make after commencing a gluten-free diet. In a trial phase, the suspected foodstuffs can be withdrawn for a period of time, thereafter to be introduced one at a time.

Accurate testing is available for the diagnosis of coeliac disease and lactose intolerance. However, there are no reliable tests to diagnose other food intolerance. Many alternative therapists offer such tests, but there is no documented evidence that these do what they promise. Voksentoppen Barneklinikken, Rikshospitalet HF, is a special hospital for children with allergies. There are no such special institutions for adults. Adults must first contact their general practitioner who thereafter can refer them to an appropriate specialist, e.g. a gastroenterologist, pulmonary physician or Ear, Eye, Nose and Throat (ENT) specialist. There are also regional centres of competence within asthma, allergies and hypersensitivity (RAAO) where patients with complex illnesses can be reviewed.


The only treatment for those with food allergies is to avoid the foods to which you are intolerant. It is often safest to prepare most food yourself. When pre-prepared food is used, it is important to always read the ingredients list carefully. When visiting a restaurant or eating out, it is important to ask about the ingredients in the dishes and to inform the establishment about any allergies or hypersensitivity.

A balanced diet is extremely important, particularly in childhood. Nutrients in foodstuffs that are eliminated must be replaced. In the case of milk allergy, it is important to ensure sufficient intake of calcium and B-vitamins. For very young children, the intake of proteins is important to keep an eye on.

Infants (< 3 years old) with an allergy to cow’s milk should be given a complete milk replacement (available on prescription from a pharmacy). In a wheat-free diet, it is important to ensure that the diet contains sufficient protein, fibre and minerals. Intake of vitamin C can be low if many fruits and vegetables are removed from the diet. A doctor can make a referral to a clinical at the hospital’s outpatients department for individual dietary guidance.


Individuals who are vulnerable to experiencing serious life-threatening allergic reactions should be provided with, and carry, an adrenaline syringe (EpiPen or Jext). The adrenaline injection is given as an “antidote” if a person inadvertently ingests something to which he/she is allergic. Allergy medicines taken for other allergic conditions, e.g. pollen allergy, may also reduce symptoms arising after ingestion of non-tolerated foods. However, it is not usual to take regular medication for food allergies.

The Food Allergy Register

In the event of serious reactions to food, a notification should be sent to the Food Allergy Register at the Norwegian Institute of Public Health. The criteria for reporting of incidences are that the patient has consulted his/her doctor within 24 hours of eating the foodstuff. The Food Allergy Register was created in order to acquire further knowledge about food reactions, their severity, which foods are reacted to and who is affected.