Gluten, peanuts, shellfish, pistachios… Food allergy is characterized by a set of abnormal immune reactions triggered by the body during the ingestion of food.
Food allergies concern 2 to 6% of the population and mainly affects children. Health professionals benefit from few therapeutic responses, while the number of consultations for allergic symptoms is increasing. However, symptomatic management is possible and knowing how to apply the right gestures makes it possible to avoid serious manifestations such as anaphylactic shock.
What is a food allergy?
food allergy is characterized by a set of abnormal immune reactions triggered by the body during the ingestion of food. Normally, this food is not harmful to the body, but when it causes an allergy, it becomes a allergen : we speak then food allergy. “Allergy is defined as the reaction of the immune system to a substance foreign to the body, to something that should normally be tolerated. Food allergy is to be differentiated from food intolerance, which causes symptoms with respect to an enzyme”, specifies Doctor Madeleine Epstein, allergist. And to complete, “we see more and more allergic patients, especially babies. This growth is explained by the increasingly strong presence of processed and ultra-processed food, causing inflammatory phenomena.
What is the list of the most common food allergies?
Foods that may trigger an allergy are reviewed periodically based on scientific evaluations. Here is the list of allergens food The most common :
- Gluten (frequently found in cereals, wheat, rye, barley, oats, spelled, kamut);
- Eggs ;
- Milk ;
- The fish ;
- The crustaceans ;
- Peanuts ;
- soy;
- Nuts (almonds, walnuts, pecans, Brazil nuts, cashews, macadamia, pistachios);
- Celery;
- Mustard;
- Sesame seeds ;
- Sulfur dioxide commonly referred to as “sulphites” (present in wines, spirits, dried fruits)
; - Lupine (herbaceous plant);
- Molluscs.
When is a food allergy triggered?
Food allergy is triggered by two major steps.
► You must have been first contact with the allergen : this first contact is asymptomatic, but generates sensitization to the food. Antibodies are produced, in particular immunoglobulin E (IgE). These IgE bind to reactive cells called mast cells.
► Subsequent contact with ingested food leads to binding with IgE, which stimulates mast cells, which release histamine. “Histamine is the first chemical mediator released during hypersensitivity reactions. Mast cell degranulation allows the release of histamine and then other inflammatory mediators.
However, allergic reactions do not always occur during the second contact. “The allergic reaction can start very late in lifeand we do not know why, says Doctor Epstein. It occurs the day when all the co-factors are met, such as the nature and quantity of allergen, the state of the immune system, the possible taking of medication, etc. This is exactly why the allergic reaction is unpredictable and fickle. And to add that “just because the patient had a violent reaction once, does not mean that all subsequent reactions will be as severe”even if the ingestion of the food can be a source of anxiety.
What are the symptoms of a food allergy?
THE food allergy symptoms are very varied and depend on each patient. Usually, food allergies can lead to symptoms:
- Cutaneous : localized or generalized urticaria, more rarely an outbreak of eczema;
- A oral syndrome : edema of the lips, itching of the palate and tongue;
- digestive : abdominal pain, diarrhoea; colic, frequent crying and gastroesophageal reflux in the baby;
- Respiratory : allergic rhinitis, asthma.
Some food allergy symptoms require emergency medical carenotably laryngeal edema and the anaphylactic shock. Laryngeal edema (formerly called angioedema) is characterized by rapid swelling of the mucous membranes of the upper respiratory tract (larynx, pharynx), which can extend to the neck and head. It’s a severe allergic manifestationresulting in respiratory discomfort that can go as far as asphyxiation.
THE anaphylactic shock is more common in adults than in children. Anaphylaxis affects one or more organs with varying severity: urticaria, laryngeal oedema, dyspnoea, digestive signs, cardiovascular damage (heart rhythm disorder) and malaise (pallor, drop in blood pressure, loss of consciousness). This is the strongest allergic reaction that can involve the vital prognosis. Allergic shock is therefore a vital emergency.
How long does a food allergy last?
The duration of food allergies depends on the allergenic foods. “Most often, an allergy to milk or eggs in children heals when they start kindergarten. Some patients will heal spontaneously at some point in their lives“. On average, a food allergic reaction occurs within 30 minutes of ingesting the food. Often the manifestations are immediate.
Treatment is mainly symptomatic. Of the antihistamines are prescribed in case of allergic rhinitis, digestive or cutaneous symptoms. Atopic eczema is treated by applying topical corticosteroids while asthma attacks are treated with a bronchodilator.
What to do on a daily basis?
The first reflex is to avoid ingesting the substance responsible for the allergy, by checking the lists of ingredients, whose allergens are highlighted in bold type: this is the elimination diet. But be careful: each patient must find their allergen, which is not necessarily on the list. Patients with known food allergies are advised to carry a first aid kit constantly. This emergency kit will mainly contain:
- A self-injectable adrenaline pen in the event of a severe reaction (anaphylaxis);
- Of the antihistamine drugs if the symptoms are mild;
- Possibly a bronchodilator.
However, Doctor Epstein would like to remind you that it is not enough to have the first aid kit. “Therapeutic education is essential. Every patient, parent and those around an allergic child should know how to use the self-injectable pen. It is very easy to use, but you have to practice several times with a training pen in order to overcome apprehension and act very quickly in the event of anaphylactic shock.“The gesture consists of positioning the pen on the outer edge of the thigh and maintaining pressure on the trigger button for 10 seconds. And the allergist continues”you must use the pen as soon as you are afraid: if you are wondering whether to use it, the answer is yes, especially in the event of respiratory signs“. After one adrenaline injectionhospital treatment is necessary.
When to desensitize to a food allergy?
“Desensitization is indicated in case of allergies to pollens or dust mites (air allergens), those for which we have extracts.“In the case of food allergies, the treatment is induction of tolerance. This treatment is often offered to adult patients whose diet of fruit is considerably reduced or in the event of a cross-pollen-food allergy (eg birches/fruits). “We offer apple tolerance induction, which is an effective treatment not only for food allergy, but also for pollen allergy“, illustrates the allergist. “It is also offered to children for foods that are difficult to avoid, once the allergic diagnosis has been confirmed.. Treatment consists of administering small doses of the allergen in an increasing fashion. “This treatment is performed under medical supervision, in a hospital environment. The protocol is quite cumbersome, but well supervised, and in some patients, the induction of tolerance can really help“, continues Doctor Epstein. Due to the loss of tolerance if the regular consumption of the allergen is interrupted, there is currently no possibility of stopping treatment. For the time being, immunotherapy (desensitization ) remains a lead in the research stage.
Thank you to Doctor Madeleine Epstein, allergist doctor.