Food allergy in adults

What is it about ?

A food allergy occurs when foods or food ingredients such as colorings and preservatives trigger allergic symptoms. In the event of an allergic reaction, the body produces an abnormal amount of antibodies directed against these products.

The foods that most commonly cause serious reactions are nuts, seeds, fruits and vegetables, but also milk and wheat. Certain medications, such as anti-inflammatories and antihypertensives, as well as alcohol can play a role in the development of an allergic reaction to food.

People who are allergic to dust or pollen also have a higher risk of developing an allergic reaction to certain foods, because both the food and the dust contain proteins that share similar characteristics. This is called a cross allergy. For example, someone allergic to birch pollen is more likely to be allergic to fruits, root vegetables, legumes and nuts.

What is its frequency?

3 to 4 adults out of 100 have a food allergy. Studies show that 20 out of 100 people avoid certain foods because they experience symptoms when eating them. However, this does not always mean it is an allergy. In these cases, we will speak of a pseudo-allergy.

Symptoms usually begin in childhood, but an allergy can also begin in adulthood.

How to recognize it?

A food allergy can trigger both local and general symptoms. Oral allergic syndrome (OSA) is common. This is a set of symptoms (a syndrome) that occur following contact with food. These symptoms can be, for example, tickling of the lips and tongue, swelling of the throat. They can be triggered, for example, by eating raw fruits and vegetables. People who are also allergic to trees (birch) particularly suffer from this. Additionally, gastrointestinal symptoms are often present, such as nausea, vomiting, diarrhea, and abdominal pain. On rare occasions, an extreme, life-threatening reaction ( anaphylactic shock ) may occur, with a drop in blood pressure, difficulty breathing, and an itchy rash. This reaction sometimes occurs due to the association of a food allergy with exercise. The reaction occurs only if you exert yourself within 4 hours of eating.

Other pre-existing allergy symptoms may then also worsen, such as asthma , hay fever or skin rashes (eczema).

How is the diagnosis made?

The doctor will first carefully check which foods trigger the symptoms, what your complaints are, their severity, how long it takes for them to appear and their duration. He will also check if you have other allergies and if there are cases of allergies in your family.

The most important additional test is the skin allergy test (prick test). Droplets containing a suspect food are applied to the skin. With a fine needle, the skin is pricked through the drop. In the event of an allergy, a red swelling (blister), sometimes irritating, appears after about fifteen minutes. If this test is not available, a blood test will be carried out to determine specific antibodies directed against the suspect foods. If we think of an association between a food allergy and a respiratory allergy (cross allergy), we will also test you for pollen allergy.

It is possible that you react to a test, even though you have no symptoms when you ingest the tested food. In this case, we will speak of a non-significant allergy: you are indeed allergic, but this is of no importance in relation to your diet. You can therefore eat the food in question without worrying.

What can you do ?

Avoid foods that trigger symptoms. It can be helpful to keep track of everything you eat for a while to find out which ingredient is causing you problems. If symptoms are severe or you don't know what you are allergic to, get tested first.

In fact, the fact of not tolerating certain food components is far from always being synonymous with an allergy. For example, an irritable bowel , lactose or gluten intolerance (celiac disease) can trigger the same type of symptoms, even though there is no question of allergy.

What can your doctor do?

If it is unclear which food triggers the symptoms and the symptoms are not too severe, the doctor sometimes suggests an elimination diet (elimination diet). A certain number of foods are then eliminated from the diet. If the symptoms disappear, they can be added back to the diet one after the other. The product that causes the symptoms to reappear is likely the cause of the allergy.

In case of mild forms of allergy, the doctor may prescribe an antiallergic medication (antihistamine). In case of severe symptoms, the doctor sometimes gives a single dose of cortisone or a short course of cortisone treatment.

People who have already had a serious, life-threatening reaction ( anaphylactic shock ) should always carry an adrenaline injector (Epipen®, Jext®). Thus, they can self-inject if the situation arises again. The pharmacist will explain to you how it works. The doctor will also explain to you whether treatment for a pollen allergy may be helpful.