Food allergy

Nausea, an ill feeling, or a rash: people with a food allergy always experience the same symptoms. They occur after eating even tiny quantities of the food concerned.

However, food allergies are less common than many believe. There are often other reasons for the symptoms. So a careful diagnosis is important. The doctor can then determine whether there actually is an allergy and, if so, treat it appropriately. If it turns out that no allergy exists, the foods can often continue to be eaten.

Someone who has a food allergy often reacts when consuming small amounts of a food. There is a wide range of symptoms and various organs may be affected.

Possible symptoms include:

• swelling of the mucus in the mouth and throat
• itching
• rashes and reddening
• hives
• nausea
• stomach or gastrointestinal problems, for example diarrhea
• breathing problems

The allergic reaction usually begins within half an hour, but at most a few hours after consuming the food.

A food allergy can also cause an anaphylactic reaction: drop in blood pressure, loss of consciousness, rash, and swellings in the face are possible symptoms. If swelling occurs in the airways it can cause breathlessness.

With fruit and vegetable allergies, the symptoms tend to be milder, such as rashes. It is more often nuts and shellfish that cause more severe allergic reactions.

With food allergies, the immune system reacts to proteins that are actually harmless as if they are foreign bodies.

Some people have a genetic tendency to have allergic reactions. In addition, a food allergy may occur in conjunction with a cross-sensitivity to pollen. In other words, people with a pollen allergy may also have an allergic reaction to certain foods. This is because the proteins in the triggering food are very similar to those in pollen. For example, birch pollen can cause a cross-sensitivity to apples, celery, nuts, or carrots. Apart from this connection, however, the precise causes of a food allergy are not understood.

Typical triggers include: 

• peanuts, walnuts, hazelnuts
• pulses (legumes)
• cow’s milk, hen’s eggs, soya, wheat
• stone fruit and pome fruit
• vegetables such as celery or carrots
• fish and seafood
• meat

Around 4 percent of the population in Germany have a food allergy. They can begin at any age. How it progresses varies greatly, depending on the trigger and the age of the person.

It is difficult to say how long a food allergy will last and how it will evolve. Children who are allergic to milk protein, wheat or soya have a good chance that their problems will disappear after a few years. This is because the body learns to cope with the substances triggering the allergy.

Someone who first reacts to foods such as fish or seafood when they are of adult age usually finds that the allergy is long-term. Nut allergies also often last longer or for life. Around half of children with a food allergy later develop an allergic asthma or an allergic rhinitis.

The probability that an allergy will be permanent rises along with the severity of the complaints. Significant reactions in allergy tests also point to a lasting allergy.

Skin and blood tests, for example, can verify whether someone has a food allergy. Doctors use the tests to see whether the immune system reacts excessively, i.e. allergically, to particular substances.

In a skin prick test, various potential allergens are placed on the forearm, spaced out at regular intervals. The skin is then scratched lightly in these locations to allow the substances to enter the skin. The skin on the forearm is then observed to see whether it reddens or itchy hives break out. In a blood test, the doctor determines whether the body has formed specific anti-bodies (in particular IgE antibodies) against a food.

However, these types of tests are usually not enough to identify a food allergy definitively. So a provocation test is also often carried out: with this, the sufferers eat the suspicious food under medical observation.

Depending on the individual situation, a daily diary of food and intake and symptoms or an elimination diet may help.

With a food allergy, the main thing is to avoid the trigger food. In the short term, severe symptoms can also be treated with drugs. As a rule, drugs are not used on an ongoing basis with food allergies.

The most severe form of allergic reaction is called anaphylaxis. With this, the entire body reacts and at least two organs are affected simultaneously – for example the skin and the airways or the gastrointestinal tract and the cardiovascular system. Should this type of anaphylactic reaction occur, a special emergency kit is used. Severe symptoms can be treated with the drugs in the kit. They also help prevent any deterioration.

It is also possible to save information about severe allergies in the emergency data record on the electronic medical data card.

For more detailed information, for example on how a food allergy is treated, go to gesundheitsinformation.de.

There is more information on food allergies at allergieinformationsdienst.de (in German).