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Dermatologists Caution That Atopic Dermatitis is a Strong Precursor to Food Allergies

Posted: March 7, 2011

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In contrast, sensitization to food is not the same as being allergic to food. Specifically, an allergic sensitization to food is determined by the presence of specific IgE antibodies – which are antibodies made in response to foreign proteins that come into contact with the body – in the blood and confirmed by blood or skin tests.

In order to understand the complex relationship between food allergies and atopic dermatitis, Hanifin noted that people with atopic dermatitis make larger amounts of IgE than any other group of patients.

“As dermatologists, we have seen children with highly restrictive diets who might have more than 20 positive skin or blood tests – but we now know that a positive test is not an allergy unless it is confirmed by an actual food challenge,” said Dr. Hanifin. “In the meantime, children may be malnourished and experience a host of other problems by not having proper nutrients in their diets. The fact is that children may only have a sensitization to the foods, but are being treated as if they have food allergies. We’re hoping that these new guidelines will help clear up this misinformation and ensure a proper diagnosis.”

According to the new guidelines, it is recommended that “… children less than 5 years old with moderate to severe atopic dermatitis be considered for food allergy evaluation for milk, egg, peanut, wheat and soy, if at least one of the following conditions are met:

  • The child has persistent atopic dermatitis in spite of optimized management and topical therapy.
  • The child has a reliable history of an immediate reaction after ingestion of a specific food.”

Hanifin further explained that in the past, positive blood tests and skin tests would be mistaken for a food allergy, because they would indicate the presence of IgE antibodies—which are higher in patients with atopic dermatitis. “However, those antibodies are not diagnostic and the only way to diagnose food allergy is with a strong history of reactions or a challenge—where you feed patients the food indicated by tests and see if they have an immediate reaction to it,” said Dr. Hanifin. “This is done in a doctor’s office, using small increments of the food in question and increasing the amount until an allergic reaction occurs or does not occur. Usually a parent can pinpoint if a child has a true food allergy because the allergic reaction will appear so quickly with lip swelling or hives, quite distinct from simply food intolerance.”