Study suggests over-diagnosis of food allergy in children

By Caroline Scott-Thomas

- Last updated on GMT

Related tags Food allergies Allergy

Many children’s diets are being unnecessarily restricted due to overreliance on blood tests for food allergies, claims a new study in the Journal of Pediatrics.

The Centers for Disease Control and Prevention said late last year that there has been an 18 percent rise in the prevalence of food allergies among US children from 1997 to 2007. Parents of almost four percent of American children report a food or digestive allergy in their child.

This latest study challenged the suspected food allergies of 125 children. Together, the children in the study were avoiding 177 different foods, primarily due to blood test results. The authors explained that immunoassays can be difficult to interpret, none is 100 percent accurate, and the tests’ ability to predict true food allergy has only been validated for five foods: Hen eggs, peanuts, tree nuts, cow’s milk and fish.

Depending on the reason for food avoidance, 84 to 93 percent of foods were restored to children’s diets following oral food challenges.

Senior author and Edelstein chair of pediatric allergy and clinical immunology at National Jewish Health​Donald Leung​said: "When you are able to restore foods such as dairy products, egg, peanut, wheat, and vegetables to a child's diet, it improves their nutrition, reduces the need for expensive substitute foods and makes meal time easier for families.”

The authors performed oral food challenges for 71 foods where the existence of a true food allergy was ambiguous. In 86 percent of those cases, the child passed the food challenge and the food was restored to the child’s diet. Sixty-six of the 177 foods avoided because of blood tests were restored to children’s diets.

Overall, the study led to 325 foods being restored to the diets of 125 children.

Lead author of the study and assistant professor of pediatrics at National Jewish Health David Fleischer said: “People with known food allergies, especially those with a history of anaphylactic reactions, should by all means avoid those foods. 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. These overly restrictive diets have been chosen for a variety of reasons, but overreliance on immunoassay tests appears to be the most common cause.”

The most common allergies among children are cow’s milk, eggs, peanuts, tree nuts, soybeans and wheat, according to the American College of Allergy, Asthma and Immunology (ACAAI), while the most common among adults are peanuts, tree nuts, fish, crustaceans, mollusks, fruits and vegetables.

Source: Journal of Pediatrics

Published online ahead of print

“Oral Food Challenges in Children with a Diagnosis of Food Allergy”

Authors: David M. Fleischer, S. Allan Bock, Gayle C. Spears, Carla G. Wilson, Naomi K. Miyazawa, Melanie C. Gleason, Elizabeth A. Gyorkos, James R. Murphy, Dan Atkins, and Donald Y. M. Leung.

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