Food Allergies

Adults and children appear to uneven food allergy. If only 3.5% of adults are subjects, nearly 10% of children are concerned. How to recognize the symptoms? What are the foods most commonly involved? What priority treatment?
 
The digestive tract has a very rich local immune system at mucosal completed by draining lymph node is very important. This system protects the body from viral antigens, bacterial and parasitic an effective immune response that seeks to eliminate. The immune system must also recognize the dietary protein to accept their passage through the mucosa. A food does contain many proteins. Many of them turn out to be allergens. A food may well contain some forty different allergens.

A predisposition to allergy
The natural tolerance to foreign food proteins is a biological feature entirely original. In some children, there is a family plot called "atopic". Atopy is a genetic predisposition to develop antibodies of class IgE against allergens (protein environment) coming into contact with 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 develop 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 parasite or an intestinal candidiasis and any cause of increased intestinal permeability to protein foods).

Symptoms
The infant may be sensitive to the food early, even in utero during pregnancy. Food allergy in infants often reaches the digestive 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, recurrent ENT infections, 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 figures suggest 30 to 50%. More atopic dermatitis is severe, the more likely a food allergy is involved.

The main food in question
Some allergens are responsible for 90% of cases 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, crab, lobster, langoustine, lobster ). Other foods are more rarely involved (10% of cases): exotic fruits (pineapple, banana, passion fruit, kiwi, persimmon, lychee, mango, coconut, papaya), legumes (beans, beans, peas , chick peas, soya), wheat flour, mussels, 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, laurel, lilicées, yeast baker, onion, orange, pigeon, pistachio, pollen, radishes, grapes, kidney, buckwheat, sesame, tomato ...

Before the age of 1 year, the major allergens are egg, peanut and milk cows. Between 1 and 3 years, the major allergens are the egg (31%), groundnuts (18%), milk (12.5%), fish (12.5%), peanut oil , mustard.

Some risk factors have been identified: the diversification of food, widespread use and increasing protein added to processed food industry because of their properties, etc.. The food industry introduces indeed constantly new ingredients in its preparations.

Some are potentially allergenic:

-News cereals;
-Various dried fruits (peanuts, hazelnuts, walnuts, pistachios, almonds);
-Various exotic fruits (persimmon, kiwi, lychee, etc.).
-Mixed seeds (poppy, sesame, etc.).
-Food additives varied protein (alpha-amylase, carmine, cochineal, caseinates, vegetable gums, lysozyme, etc.).
-Presence of traces of protein in vegetable oils (peanut, nuts, sesame, soybean, sunflower);
-Modified allergenic proteins (textured soy, surimi fish, etc.).
The development of latex allergy is the source of cross allergies with some plants. Allergy to dyes and other food additives is often suspected but difficult to prove. The main food additives under investigation 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 meanwhile well known. Most sensitizers are probably those containing sodium metabisulfite (E222 to E227). Sulfites are so prevalent in the food and pharmaceutical industry that their questioning is not always possible.



The diagnosis of food allergy
The diagnosis is difficult. It requires the use of an immuno-allergy specialist specializes 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 is 20% where 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 IgE specific 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 broth, lysozyme from egg white in some cheeses (Gruyere, Emmental) for example. Peanut oil contained in some milk diet was the cause of atopic dermatitis. Currently, the formula milks do not contain more. Observations of children sensitized in utero to peanuts have shown that pregnant mothers ate large amounts of peanuts sitting watching television.

Treatment
The absolute foreclosure of the food responsible should be recommended. It requires vigilance at all times when eggs, milk, peanut or soy. When an allergy to many foods is proved, the plan recommended to be established by a dietician experienced in order to avoid nutritional deficiencies, particularly vitamin.

Pharmacological treatment comprises an antihistamine and a medication to protect the intestinal mucosa of the risk of local release of histamine (disodium cromoglycate: Nalcron). In cases 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 complete a contract for custom home schools as provided by the circular of July 22, 1993, No. 93-248 .

Many still unknown about the natural history of food allergy. It is not currently possible to predict the evolution of allergy to proteins in cow's milk often cured at 5 years, the peanut allergy often persists throughout life. Many factors, not all identified, combined to that after one to three years, randomly, the child is healed or healing, or in a stable condition, or otherwise in a state of sursensibilisation.