Food allergies in children, as a diagnosis, are more common than before. But are we over-diagnosing? The main issue is that the tests we perform, especially the blood tests for allergens, may show a positive “in vitro” allergy but “in vivo”, AKA in real life, there may not be a clinically significant allergy.

This growing issue is discussed in the always excellent Wall Street Journal Health Section (When Is Your Kid’s Food Allergy Really a Food Allergy?). One of their good quotes:

“Are these blood tests being overused? Possibly. Misinterpreted? Absolutely,” says Robert Wood, director of Pediatric Allergy and Immunology at Johns Hopkins Hospital, who is part of a task force writing guidelines for diagnosing and managing food allergies. “A lot of these kids truly have food allergies, just not to all the foods that they are being told they have allergies to.”

A national sampling from 2005-2006, which also included blood tests, found that 9% of U.S. children had a sensitivity to peanuts, 7% to egg; 12% to milk and 5% to shrimp. But experts believe that only about one-tenth of those children will actually have allergic reactions to those foods. Even the true rate of fatal reactions to food allergies is hard to gauge: Estimates range from as low as five to as high as 200 per year.

Here’s an excellent graph from the article:

The bottom line?

Many children do have serious food allergies, but perhaps they should be evaluated more frequently, if possible, by an allergist who can also perform allergy skin tests or a food challenge.