RODALE NEWS, EMMAUS, PA—Nearly every school nowadays has peanut-free lunch options for kids with peanut allergies, and it has become de rigueur at children’s get-togethers and birthday parties to include alternatives for kids with dairy allergies. All this anecdotal evidence suggests that food allergies are skyrocketing. There’s scientific evidence as well. A recent study in the Journal of Allergy and Clinical Immunology found that peanut allergies alone have tripled over the past decade.
But another study just published in the heavyweight Journal of the American Medical Association suggests something else may be going on. Namely, that many of these food allergies may be a result of simple confusion—confusion over what defines a food allergy, how we test for them, and how we treat them. "The world of food allergies is evolving all the time," says the study's lead author Jennifer Schneider, MD, MS, healthy policy fellow at Stanford University and the VA Palo Alto Healthcare System. "There's not a widely accepted clinical test for diagnosis," she says, "And as practitioners we haven't been able to definitively say what a food allergy is."
THE DETAILS: The study reviewed existing literature on the prevalence, diagnosis, management, and prevention of food allergies. The authors analyzed 72 studies of food allergies to cow’s milk, eggs, peanuts, tree nuts, fish, and shellfish, and came up with some interesting findings.
Most important, there doesn't seem to be a single accepted mode of diagnosing food allergies. Some of the studies under review used self-reports (the authors noted that allergy prevalence was always higher when this method was used), others used skin-prick tests, and still others used a blood test that measures immunoglobulin E (IgE), an antibody produced during an allergic reaction. Very few studies used food challenges, a clinical test whereby a patient is exposed to the suspected food and monitored for allergic reactions. This despite the fact that food challenges are by far the most accurate tests for diagnosing food allergies. Due to this lack of diagnostic uniformity, the authors noted that it's unclear whether food allergy prevalence actually is increasing. Some studies suggested that 1 to 2 percent of the population suffers from them, while others put the number as high as 10 percent.
WHAT IT MEANS: Bottom line is, the study authors believe the lack of uniformity in diagnosing and defining food allergies is likely leading to an overdiagnosis of the condition. Other research has shown that people with purported food allergy symptoms (such as rashes or stomach aches) who test positive for food allergies via skin prick or IgE blood test have a less than 50 percent chance of having a food allergy. Which could lead to unnecessary dietary restrictions that result in nutrient deficiencies. It can also cause angst, and needlessly put people in awkward social situations.