Food allergies are serious business -- just ask 18-year-old Dane of Charlotte, North Carolina. With milk, eggs, peanuts, shellfish, chicken, potatoes, and garlic, and many other foods, on his do-not-eat list, he suffers from true, life-threatening food allergies.
To avoid a trip to the emergency room, everything Dane eats must be made from scratch: "I don't eat in restaurants or from vending machines," he says, "[and] I try not to be around a lot of food, which makes it a little isolating because so much of our culture and socialization revolves around food."
But there are many allergy sufferers who practice the same devout food avoidance as Dane but don't really have to, according to a paper published Wednesday in the Journal of the American Medical Association.
While a considerable percentage of Americans report that they have a food allergy, the true incidence of food allergies may be far less, says Dr. Marc Riedl, an allergist and immunologist at the University of California, Los Angeles, and an author of the paper.
"If you look at the numbers, roughly half of the people who believe they have an allergy, do not," Riedl says.
Some of these misled patients are self-diagnosed, misinterpreting heartburn or food intolerance for an allergy, he says. Others have seen doctors who have misinterpreted allergy test results and hence have been told to avoid foods that they don't actually have to.
the problem might lie in testing. Traditional methods, such as the skin prick test or a blood test, indicate only whether the body produces enough antibodies to fight against a certain type of food. But that doesn't necessarily mean the body can't tolerate the food.
Dane says this is true of some of the families in his allergy support group.
"Some have mistakenly been told that a positive skin test means that their child is allergic," he says. "This is not the case."
This is one of the biggest take-home messages of Wednesday's paper, says Dr. Hugh Sampson, chief of pediatric allergy and immunology at New York's Mount Sinai School of Medicine: One positive allergy test result does not a food allergy make.
While many agree that tests can produce many false positives, some worry that this study might make people less vigilant about food allergies.
"It presents one side of the story," said Robyn O'Brien, director of the Allergy Kids Foundation. "We absolutely should exercise precaution until further testing and further science is available."
The problem is, there is no unified definition of what a food allergy is or how to test for it reliably, Riedl says, which can result in overdiagnosis.
In an attempt to address the issue, the National Institute of Allergy and Infectious Diseases commissioned Riedl and his colleagues to review the research on food allergies from 1988 to 2009. The resulting paper will be used to help a panel of experts write new guidelines on how to define, diagnose and treat food allergies. The new guidelines are scheduled to be released by the end of June.
Prevalent overdiagnosis or mistaken self-diagnosis of food allergies is nothing new, says Dr. Wesley Burks, chief of the Division of Pediatric Allergy and Immunology at Duke University Medical Center.