Food allergies develop when the immune system misinterprets a food as harmful and develops an immune response against the food. If a child develops allergy antibodies (called IgE) to a food protein, reexposure to that food may be accompanied by a release of chemicals that produce the allergic symptoms.
Leonard Bacharier, M.D., associate professor of pediatrics at Washington University School of Medicine in St. Louis and Clinical Director of Pediatric Allergy, Immunology and Pulmonary Medicine at St. Louis Children's Hospital, said that eight foods that cause 90 percent of food allergies, including:
- Tree nuts (such as walnuts, pecans, cashews, almonds)
Symptoms of an allergic reaction can range from mild to severe, and may include one or more of the following:
- Hives (a red intensely itchy rash)
- Tingling or swelling of the lip, tongue and/or throat
- Difficulty breathing, coughing and/or wheezing
- Nausea and vomiting
- Abdominal cramps
- Drop in blood pressure
- Loss of consciousness
Anaphylaxis is a combination of several of these symptoms and is a life threatening medical emergency.
The only effective approach for the treatment of food allergy is dietary avoidance.
"This requires extreme dedication and attention to detail," Bacharier says. "Parents and caregivers of food allergic children must become experts at reading ingredient labels on all foods. Peanuts, soy, wheat, milk and eggs are common ingredients in many packaged foods, recognition of the other terms used on labels which indicate the presence of milk or egg proteins, such as casein and albumin is critical."
"As a general rule: if a product doesn't have a label, people with food allergies should not eat that food," Bacharier says.
Even with meticulous attention to ingredients, accidental ingestions occur. Children who have experienced a significant allergic reaction to a food should always carry and know how to use injectable epinephrine and antihistamines to treat reactions, and should also wear an identification bracelet describing the allergy.
The good news is that most children allergic to milk, soy, egg, and wheat will lose their sensitivity as they grow. While allergy to egg and milk carry a good prognosis in terms of being "outgrown" during the preschool years, allergy to peanuts, tree nuts, fish and shellfish are generally lifelong.