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True food allergies must be distinguished from intolerances, particularly in children and teenagers, so a child is not needlessly restricted from certain foods.
Food allergies are caused by a specific, reproducible immune response to a particular structural aspect of a "problem food." Food allergies are most commonly caused by allergic antibodies. This means the body produces a protein that reacts with an "antigen" from the particular food to release histamine, which causes adverse reactions in the digestive or respiratory systems, or on the skin.
While any food can be the source of an allergic reaction, the most common food allergies are caused by peanuts, eggs, milk, shellfish, wheat, tree nuts, soy and fin fish, explains Melinda Braskett, M.D., medical director, UCLA Food and Drug Allergy Care Center.
In many cases, an allergist can diagnose food allergies from the history and supportive testing using either a simple skin prick test or blood work. Oftentimes, the diagnosis of a food allergy is still unclear. Your child's allergist may recommend an oral food challenge, where a small amount of the problem food is given to the child under direct supervision, in a safe and controlled setting. Once the allergy is accurately identified, avoidance of the specific problem food resolves all symptoms. Antihistamines, epinephrine and steroids are used to treat the symptoms of allergic reactions. For people with severe allergies, epinephrine, a small dose of adrenaline, should be kept on their person at all times. This therapy can be life saving.
Many food intolerances can be thought of as irritant responses rather than an immune system problem. Food intolerances can occur when a child is unable to properly digest or break down the food. For example, people with lactose intolerance are missing the enzyme lactase, and have trouble digesting milk and dairy products. In general, children with food intolerances do not have acute health risks if the food is ingested in small amounts.
"Parents who believe their children suffer from severe food allergies typically restrict them from eating numerous foods," notes Dr. Braskett. "Proper diagnosis and treatment of food allergies are key to ensuring that a child is not needlessly restricted from enjoying foods and activities that may, in fact, not pose a threat."
Symptoms appear within a few minutes or can take up to two hours
Symptom onset are usually delayed: