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.

Food allergy, what is it

 A food allergy is an abnormal reaction of the body's defense system (immune system) to a food: the immune system considers the food as something foreign that it must reject.

This is not the same as a food intolerance. In case of food intolerance, there is no allergic reaction. Generally, with food intolerance, the person lacks certain substances (enzymes) to digest certain foods.

What are the causes of food allergies in children?

In infants and young children, cow's milk is most often the cause of the allergy.

When you start giving your baby solid foods, (chicken) eggs are a common cause.

We see that school-age children who are allergic to birch pollen are also more sensitive:

• raw fruits and vegetables;
• with nuts ;
• vegetables that grow in the ground (like carrots or turnips).

In adolescence, wheat is a common cause of allergies.

How common are food allergies in children?

One in 2 parents think their child under 2 has a food allergy. But figures show that out of 100 children, only 2 to 7 children have a food allergy.

Parents mistakenly think that their child is allergic to foods when they see, for example:

• that he has a bad appetite;
• that he vomits;
• that he makes a lot of referrals;
• that his stools are a little softer.

How to recognize food allergies in children?

Several different signs (symptoms) may appear. They can appear immediately after the meal or several hours (and even days) later. The child may have:

• skin problems: itchy rash and red spots. This can be hives , but also eczema ;
• eye problems: itchy, watery eyes ( conjunctivitis ), swollen eyelids;
• gastrointestinal problems: vomiting , diarrhea , stomach aches . Itching in the mouth, the gateway to food, is common;
• respiratory problems: sneezing, runny nose and wheezing are rather rare and most often due to hay fever present at the same time;
• other signs of illness: the baby cries constantly, he sleeps poorly , he does not gain enough weight.

How is a child's food allergy diagnosed?

Your doctor can get a lot of information by asking the parents questions:

• What are the symptoms ?
• when did they start?
• at what age did the child start eating different foods?

In infants

There is no good test to diagnose a cow's milk allergy in infants. Your doctor thinks of an allergy if symptoms appear a few weeks after introducing cow's milk into the diet. These symptoms disappear as soon as cow's milk is replaced by another milk, such as soy milk. They reappear immediately when the child drinks cow's milk again.

In the case of a very severe allergy, it is possible to have the baby take an exposure test at the hospital. We give the baby a little cow's milk, then more and more. Doctors monitor his reactions.

In older children

In older children, skin tests (prick tests) and blood tests are of little use. To make the diagnosis, the doctor advises parents to no longer give the food suspected of causing the reactions to the child. Then they will give it to him again, gradually. During this test period, parents will have to note what happens in a notebook (logbook). They will observe what happens first when the food is removed from the child's diet, then when it is reintroduced. If several foods are suspected, parents will have to start giving them again one by one. If symptoms return after reintroduction of a specific product, it is likely that food the child is allergic to.

The child is generally referred to a pediatrician if he presents a severe allergy, that is to say in the event of serious symptoms or immediate reactions that could endanger his life.

What can you do ?

Breast milk is the best food for an infant.

If you think your child is allergic, write this information in a logbook:

• when do symptoms appear?
• what are the symptoms (explain them)?
• How long after the meal do the symptoms appear?
• When do you give your baby new foods?
• How does your child react when he eats these foods?

All this information can help your doctor a lot.

Monitor your child's growth, especially height and weight.

When your doctor has diagnosed a food allergy, it is important to follow the proposed diet as closely as possible.

• Until the age of 2, cow's milk is preferably replaced by special milks such as soy milk and whey. If that doesn't work, there are other (more expensive) special milks.
• In older children, foods that cause an allergy should also be completely removed from the diet. There is no point in giving them in small quantities.

It is very difficult to completely avoid certain foods in children. It often happens that the child eats it at a friend's house or during a party. This is why it can be useful for the child to always have medication with him to calm the reactions.

Most food allergies fortunately disappear around age 6.

What can your doctor do?

Parents have the most important role to play in monitoring their child's diet.

Your doctor can advise you and if necessary prescribe a medication capable of blocking the allergic reaction. If your child has serious problems, they will refer you to a pediatrician.