Food-allergy fear drives restrictive diet

DENVER, Nov. 9 (UPI) -- Food allergy patients may have too restricted a diet if doctors rely only on blood tests to determine an allergy, U.S. researchers suggest.

Researchers at National Jewish Health in Denver recommend examining a patient's history, previous reactions, type of reaction and the results of food allergy skin testing. If the evidence is mixed, they say an oral food challenge -- where patients eat the suspected food -- is the gold standard.

"People with known food allergies, especially those with a history of anaphylactic reactions, should by all means avoid those foods," lead author Dr. David Fleischer says in a statement. "However, a growing number of patients referred to our practice are being placed on strict, unproven food-elimination diets that have led to poor weight gain and malnutrition."

Overly restrictive diets have been chosen for a variety of reasons, says Fleischer, but the most common cause is over reliance on immuno assay tests -- blood tests -- which have been validated for only five foods -- cow's milk, hen egg, fish, peanut and tree nuts. For other foods, these tests are suggestive but not definitive, Fleischer says.

The study, published online in advance of print in The Journal of Pediatrics, found in cases where clinical allergy was equivocal, 84 percent of foods being avoided could be restored after an oral food challenge.