Most people know someone with food allergies. The frequency of food allergies in Western societies has been steadily increasing for the past decade, with around 8 percent of children now estimated to have food allergies. Parents are often concerned about whether their child has a food allergy and schools are also recognizing the hazards of food allergies and how to manage the problem.
Is it a food allergy?
Parents are sometimes confused by what is an actual food allergy versus an intolerance. There are a number of non-allergic adverse food reactions that incorrectly get labeled as allergies, leading to a misconception about what constitutes a real allergy to food.
Food allergies are immune mediated adverse reactions to food occurring 20 minutes to two hours after ingestion of a certain food. They are triggered by an antibody called IgE and result in immediate allergic symptoms, including any combination of eczema, itchy/runny nose, cough, wheeze, rash, hives, vomiting, diarrhea or anaphylaxis (severe allergic reaction) and even death.
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Another type of food allergy is Food Protein Induced Enterocolitis, a rare condition characterized by repeated bouts of severe projectile vomiting and diarrhea about two hours after eating milk or soy-based formula, and sometimes other foods. Non-immune mediated adverse reactions to foods, which are not allergies, include things like lactose intolerance due to deficiency of the enzyme lactase.
Food allergies are triggered by the release of histamine from allergy cells. About 90 percent of food allergies are due to milk, egg, soy, wheat, peanuts, tree nuts, fish and shellfish, although any food can cause an allergic reaction. The severity of the allergic reaction to the offending food is unpredictable. It can be mild on one occasion, but severe the next.
How are food allergies diagnosed?
Your child’s clinical history is the most important piece of information for the diagnosis of food allergy. History is aided by two forms of testing: the allergy “skin prick” test and a blood test.
Allergy skin prick testing is very sensitive. It is accomplished by introducing the allergen just under the skin, and takes about 20 minutes. Allergies are present if an itchy hive presents at the injection site. The test can be done safely in the allergist’s office, usually on the forearm or back, but patients must refrain from taking antihistamines for several days prior to the test.
The other allergy test is a blood test that detects the quantity of food-specific IgE in the blood stream. Another test, the supervised oral food challenge, can also be done, but to prevent unnecessary reactions, allergists tend to reserve this test for documenting that an allergy has been outgrown.
Can food allergies be prevented and treated?
Once diagnosed and treated with strict dietary adjustments, children with food allergies have about an 80 percent chance of outgrowing most of their allergies. The exceptions are shellfish and peanut/tree nut allergies, which only have about a 20 percent chance.
The single most important factor leading to fatal outcomes with food allergies is failure to administer intramuscular epinephrine in a timely manner. Allergists recommend that patients carry an epinephrine auto injector in case of severe reactions. You should also call 911 because anaphylaxis may need additional medications to be fully controlled. Antihistamines, like Benadryl, alone will not avert a severe reaction, so careful monitoring of the child is important to be sure the reaction is not progressing.
The recommendations for how to prevent food allergies are evolving due to recent landmark studies regarding peanut allergies. Recommendations on treatment are also changing as more research is being done. Studies recently published suggest that the use of probiotics and small doses of allergenic proteins may enhance the possibility of tolerance to allergenic foods. Likewise, the early introduction of allergenic foods, such as peanut, in children without food allergy or mild food allergy may improve chances of not becoming allergic to foods in the long run.
Many questions remain, and generalized protocols are still in development to help attain the best long-term outcomes safely for children affected with food allergies. In the meantime, your best strategy is to work closely with your allergist and learn how to avoid accidental exposures to allergenic foods. This involves special precautions when dining away from home, learning how to carefully read food labels, increasing awareness, having an anaphylaxis management plan available for caregivers and schools, and epinephrine auto injectors accessible in every environment where accidental exposure to the allergenic food may happen. There are excellent resources available for parents at www.foodallergy.org, and with your local allergist.
Elena Perez, M.D., Ph.D., is an allergist-immunologist and associate professor at UHealth – University of Miami Health System. For more information, visit UHealthSystem.com/patients/pediatrics.