Adults and children appear unequal in food allergy. If only 3.5% of adults are subjects, almost 10% of children are concerned. How to recognize symptoms? What are the foods most commonly involved? What treatments favored? The point with Doctissimo.
Food allergies in children The gut has a very rich local immune system in the mucosa, supplemented by draining lymph node very important. This system protects the body from viral antigens, bacterial and parasitic by an effective immune response that seeks to eliminate them. The immune system must recognize the dietary protein to accept their passage through the mucosa. A food actually contains many proteins. Many of them turn out to be allergens. A food can contain forty different allergens
A predisposition to allergy
Natural tolerance to food proteins is a peculiarity foreign biologically quite original. In some children, there is a family plot called “atopic”. Atopy is a genetic predisposition to develop antibodies to the IgE class against the natural allergens (protein environment) contacting the body by natural means: skin and mucous membranes (respiratory, digestive).
Breast milk and inflammation
Food allergens are the first natural allergens in contact with the body. Indeed, we know that food allergens pass, in trace amounts in breast milk. These very low amounts of dietary protein are probably the baby’s immune system to establish its immunological tolerance. In the case of atopy, there is likely a runaway process and the creation of a food allergy. It is possible that food allergy is also favored by the existence of an inflammation of the intestinal mucosa under the influence of various factors (viral infections, stress response, destruction of intestinal flora, irritation of the gastrointestinal mucosa, presence of a parasitic or intestinal candidiasis and causes of increased intestinal permeability to protein foods).
The infant may become sensitized to the food very early, even in utero during pregnancy. Food allergy in infants often reaches the gastrointestinal tract (vomiting, diarrhea, abdominal pain). It can cause total villous atrophy with persistent diarrhea, as is the case with gluten intolerance. In the older child, the symptoms are very different: anaphylactic shock, hives, swelling of lips and tongue, atopic dermatitis, diarrhea, vomiting, colic, eczema, asthma, ear infections repeatedly, etc.. The share of food allergy in anaphylactic shock for example is 3 to 15%. In asthma, it accounts for 8% of seizures. In atopic dermatitis (eczema), some argue the numbers 30 to 50%. More atopic dermatitis is severe, the more likely a food allergy is involved.
If food allergies can in theory apply to all foods, twenty, according to Prof. Monneret-Vautrin DA, food in France are the most commonly involved. Some allergens are responsible for 90% of allergies: eggs, saltwater fish, peanuts or peanut, hazelnut and drupacées (almond, walnut, apricot, cherry, quince, peach, apple, pear, plum, olive), milk cow, celeriac, celery salt and other Umbelliferae (anise, angelica, carrot, chervil, coriander, cumin, fennel, parsley, green pepper), crustaceans (spider crab, crab, shrimp, crayfish, lobster, langoustine, lobster ). Other foods are less frequently involved (10% of cases): exotic fruits (pineapple, banana, passion fruit, kiwi, persimmon, lychee, mango, coconut, papaya), legumes (beans, beans, peas , chickpeas, soybeans), wheat flour, mold, beef, potatoes, nuts, coconut, chicken, pork, mustard with a possible inducing role of mustard poultices in childhood.
Other allergens are exceptional: garlic, lamb, artichokes, calamari, coffee, chestnut, chocolate, red cabbage, chives, Saint-Jacques shell, squid, spices and condiments, snail, strawberry, royal jelly, rabbit, bay, lilicées, yeast baker, onion, orange, pigeon, pistachio, pollens, radishes, grapes, kidney, buckwheat, sesame, tomato …
Before age 1 year, the major allergens are egg, peanut and cow’s milk. Between 1 and 3 years, the main allergens are the egg (31%), peanuts (18%), milk (12.5%), fish (12.5%), peanut oil , mustard.
Some risk factors were identified: the diversification of supply, the widespread use and growing of food proteins added to the preparations for their industrial properties, etc.. The food industry, in fact constantly introduced new ingredients in their preparations.
Some are potentially allergenic;
Various dried fruits (peanuts, hazelnuts, walnuts, pistachios, almonds);
Various exotic fruits (persimmon, kiwi, lychee, etc.).
Various seeds (poppy, sesame, etc.).
Various protein food additives (alpha-amylase, carmine, caseinates, vegetable gums, lysozyme, etc.).
Presence of traces of protein in vegetable oils (peanut, tree nuts, sesame, soybean, sunflower);
Allergenic proteins modified (textured soy, fish surimi, etc.).
Development of latex allergy is the cause of cross allergies with some plants. Allergy to dyes and other food additives is often suspected but difficult to prove. The main incriminated food additives are mostly synthetic azo dyes such as patent blue (E131), erythrosine (E127), cochineal red A (E124) and yellow tartrazine (E1O2).
The role of chemical preservatives is itself unclear. Most sensitizing are probably those based on sodium metabisulfite (E222 to E227). Sulfites are so widespread in the food and pharmaceutical industry that questioning them is not always possible.
The diagnosis of food allergy
The diagnosis is difficult. It requires the use of an immuno-allergist specializing in food allergy that will decide the strategy of care.
Urticarial rash after eating can be such an element of presumption. The risk of food allergy was 20% when neither parent is allergic. This risk is 40% when one parent is allergic and up to 60% when both parents are atopic. Keeping a food diary where the ingestion of all food is carefully noted the doctor can help. Skin tests, the measurement of specific IgE, challenge testing (or exclusion diets) generally allow the diagnosis.
The problem of allergens “hidden” is important. The examples are more numerous: there caseinates in the chicken, the egg white lysozyme in some cheeses (Gruyere, Emmental), for example. Peanut oil contained in some dietary milk was the cause of atopic dermatitis. Currently, the formula milks do not contain more. Observations of children sensitized to peanuts in utero revealed that pregnant mothers ate large amounts of peanuts sitting watching television.
The absolute displacement of the food responsible should be recommended. It requires vigilance at all times when it comes to eggs, milk, peanut or soy. When an allergy to many foods is demonstrated, the regime must be established recommended by a dietician experienced in order to avoid nutritional deficiencies, especially vitamin.
Pharmacological treatment includes an anti-histamine medication and protecting the gastrointestinal mucosa of the risk of local release of histamine (cromolyn sodium: Nalcron). In case of severe allergic accidents, corticosteroids and adrenaline are necessary. When the child is at high risk of shock or acute asthma, it is necessary to fulfill a contract for custom home school as provided by the circular of July 22, 1993, No. 93-248 .
Still many unknowns about the natural history of food allergy. It is not currently possible to predict the evolution: allergy to cow’s milk proteins often heals to 5 years; the peanut allergy often persists throughout life. Many factors, not all identified, combine to that after one to three years, randomly, the child is healed, or healing, or in a stable state.