Written by Dr. Soteres in the Starfit Kids Newsletter – www.starfitkids.org
Food allergy is of increasing concern in the United States. The most common food allergens are: peanut, egg, milk, wheat, soy, tree nuts, fish, and shellfish. Any food can trigger cause an allergic reaction.
Food allergy is different than food sensitivity. Food allergies are controlled through a specific branch of the immune system and can be identified by tests for IgE (Immunoglobulin E) like the allergy skin test or a blood test. Food allergy reactions usually occur within minutes of an exposure and can be life threatening. In general, food sensitivities are not associated with life threatening reactions. Food allergy may trigger symptoms that affect the respiratory, gastrointestinal, skin, and/or cardiovascular systems. Severe reactions can occur at any age and on first known exposure to a food. The greatest risk for a fatal allergic reaction appears to be adolescents and young adults with asthma and a known food allergy to peanut, tree nut, or seafood.
The natural history of food allergy varies. For children with allergy to egg, milk, wheat, and soy, about 80% will outgrow the allergen at around 5 years old. For peanut allergy, only 20% will outgrow it.
There is no cure for food allergy. However, some clinics and research studies have had success by desensitizing patients with severe food allergy. In this procedure, the patient is introduced to tiny amounts of the allergic protein. Over the course of several weeks the immune system is trained to tolerate exposures. Successful desensitization seems to reduce the risk of a life threatening reaction due to an accidental exposure. Much research remains to gain a better understanding of the procedure and the risks.
The cornerstone for managing food allergy is: Evaluation, Education, Avoidance, and Preparation.
Evaluation and diagnosis of food allergy should start with a thorough history followed by appropriate testing. The best screening test for food allergy is the allergy skin prick test. However, both the skin prick test (SPT) and the serum IgE test (RAST Immunocap IgE) may be used. They are highly sensitive but only modestly specific. Therefore, these tests are good when suspicion of a food allergy is high.
Both the skin test and the blood test, RAST Immunocap, can identify food allergies. However, the double-blind placebo-controlled oral food challenge is the gold standard to diagnose food allergy. Food challenges can be time consuming and dangerous. It is often proposed that the IgG test for foods can identify a food-sensitivity. However, this test is not validated and making dietary changes based on IgG testing is not advised. So, referral to a board-certified allergist with expertise in food allergy is vital.
The primary treatment for food allergy is avoidance. Elimination of the causal foods from the diet is difficult to accomplish. One resource for this information is the Food Allergy & Anaphylaxis Network (www.foodallergy.org). A local resource is the support group, MOSAIC (Mothers of Severely Allergic Infants and Children) that meets monthly.
Exposure to a potentially life threatening food allergen is a fact of life for those who live with food allergy. The single most important and potentially life-saving therapy is the use of injectable epinephrine for a life threatening reaction. Delayed administration of epinephrine is a risk factor for poor outcomes like death due to an allergic reaction.
In general, having more than one injector is advised. Approximately 30% of patients with anaphylaxis will relapse. The effect of epinephrine lasts only about 15 minutes. Therefore if one must use the epinephrine then be prepared to call emergency services.
Living with food allergy can be a source of great distress, especially when the patient is a child. Many studies confirm the high degree of anxiety that parents and caregivers experience when their children are allergic to foods. Evaluation, Education, Avoidance and Preparation are the key factors in learning to live with food allergy. Seek out guidance from a board-certified allergy/immunology specialist for more information.
Information Provided By:
Asthma and Allergy Associates