What is it?Food allergy is an undesirable reaction that occurs after eating certain foods or food additives.The term food hypersensitivity (often used synonymously with allergy to food) can be defined as an adverse clinical reaction, reproducible after ingestion of allergens (substances that trigger allergy) in food, caused by exposure to a stimulus at a dose tolerated by normal people.Food allergy always involves an immune mechanism, expressing itself through a wide variety of symptoms. Food allergy is the most simplified, an exaggerated response of the body to a substance present in food.How can the food undesirable reactions.Toxic reactionscaused by the action of toxins or infectious agents. Secondary to ingestion of contaminated food, usually present acutely with fever, vomiting and diarrhea.Non-toxicFood intolerance (eg lactose intolerance (lack of the lactase enzyme that unfolds the sugar lactose). She is not immune mediated).Hypersensitivity (allergic) reaction is triggered by specific immunologic mechanisms, with an abnormal or exaggerated response to specific food proteins that may be mediated by IgE (immunoglobulin E, a protein linked to defense factors) or not.What is the frequency of allergy to food?The causes of food allergic reactions affect true 6-8% of children under three years of age and 2-3% of adults. However parents believe that the incidence of food allergy in their children reach 28%.Individuals with other allergic diseases have a higher incidence of food allergy?Yes other allergic patients have a higher incidence of allergy to food, for example, 38% of children with atopic dermatitis have food allergy and 5% of asthma.What are the main factors involved in allergy to food? Genetic predisposition (50% of patients with food allergy have a family history of allergy).The ability to produce certain food allergy.Permeability of the digestive system.Failure of defense mechanisms at the level of the gastrointestinal tract.What foods are most often involved in cases of food allergy?Among foods involved find: egg, fish, wheat flour, cow's milk, soy and shellfish. Severe reactions (anaphylactic) are, in most cases, due to ingestion of shellfish, cow's milk, peanuts, and walnuts.The dyes, preservatives and food additives?Adverse reactions to preservatives, dyes and food additives are rare, but should not be overlooked.How to manifest food allergies?Most symptoms appear minutes to two hours after ingestion. Both the nature of the reaction as its start time and duration are important for establishing the diagnosis of allergy to food. Cutaneous reactions (involving the skin) most common are: hives, swelling, itching and eczema, digestive system: diarrhea, abdominal pain, vomiting, respiratory tract, coughing, hoarseness and wheezing. In young children, the loss of blood in the stool, can cause anemia and growth retardation.Anaphylactic reaction that is?This reaction is severe, potentially fatal, sudden onset, which demands immediate relief. Anaphylaxis (anaphylactic reaction) is triggered by the massive release of chemicals that trigger a severe generalized response. Medicines, insect bites, foods, etc.., May be the trigger. In exceptional circumstances the food induces the appearance of generalized itching, edema (swelling), cough, edema, hoarseness, diarrhea, stomach ache, vomiting, tightness in the chest with a drop in blood pressure, cardiac arrhythmias and vascular collapse ("anaphylactic shock").What is oral allergy syndrome?It is a manifestation of food allergy that occurs after oral mucosal contact with certain foods. The events are instantaneous, itching and swelling of the lips, palate and pharynx .. Foods commonly involved are: fruits such as melon, watermelon, banana, peach, plum, and celery.How can the doctor make the diagnosis of food allergy?The diagnosis depends on the joint interpretation of detailed clinical history, physical examination of the data accompanied by laboratory tests.Clinical histories are important information about the food eaten. In some situations it is possible to correlate the onset of symptoms with the ingestion of certain food, in others the picture is not so evident. Chocolate rarely causes allergy, when this happens, it becomes necessary to find an allergy to cow's milk or soya, used in its manufacture.An accurate history is important in determining the "timing" of ingestion and onset of symptoms, type of symptoms, food allergens that may be causing the problem, and the risk of atopy (have several types of allergy). The elimination of an antigen strongly suspected for some weeks is commonly used in clinical practice for the diagnosis of food allergy. There is a need for reliable diagnostic tests for food allergy.Allergy tests? The (skin prick test) skin test, and detection of specific IgE antibodies in the bloodstream are more valuable when they are negative, since its high sensitivity makes them about 95% accurate for excluding IgE-mediated reactions.The RAST (radioallergosorbent test) and other similar semi-quantitative, are being replaced by more quantitative measurement of specific IgE antibodies.The "Glow immunoenzymatic (CAP-system)" was more indicative of food allergy. The use of quantitative IgE specific for food eliminates the need to test for food challenge in approximately 50% of cases.The patch test (patch test) is not currently recommended for routine use.When the history and laboratory tests indicate an immune response is not IgE mediated (cell-mediated), additional tests may be needed to confirm the diagnosis of food intolerance.Though the tests double-blind placebo controlled still constitute the "gold standard" for definitive diagnosis of food allergy, technological advances increase the value of laboratory tests.The measurement of inflammatory markers in blood and feces or immunologic reactions to foods such as hydrogen breath test for lactose intolerance or gastrointestinal biopsy to determine eosinophilic infiltration or atrophy of the villi have shown mixed results.Food allergies IgE-negative provocation tests double-blind, placebo-controlled remain the gold standard for diagnosisThe relationship between atopic dermatitis and food allergy deserves particular attention. About one third of cases of atopic dermatitis has an allergy to cow's milk and almost half of the milk-allergic infants have atopic dermatitis. The implication is that skin tests are less reliable in patients with atopic dermatitis, with up to 24% false positive. The use of tests for determination of serum allergen-specific IgE is useful in such circumstances.
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