ARI SHAPIRO, HOST:
There's a widespread assumption that food allergies are on the rise in the U.S. Now a new report from the National Academies of Sciences, Engineering and Medicine says that may not be the case. They say it's hard to know how many people actually do have allergies. Part of the challenge is that food allergies are often self-diagnosed, and they're sometimes confused with completely different conditions, such as lactose intolerance or gluten sensitivity. NPR's Allison Aubrey reports.
ALLISON AUBREY, BYLINE: These days, it seems everyone knows someone with a food allergy, so to assess the prevalence of food allergies, the National Academies put together a panel of experts to evaluate. But Virginia Stallings, a professor at the University of Pennsylvania who chaired the committee report, says they really couldn't figure this out, in part because food allergies are often not well-diagnosed.
VIRGINIA STALLINGS: There are a lot of misconceptions about what a food allergy is.
AUBREY: A common scenario is this. A parent of a young child introduces a new food - say, milk - and then notices something isn't right. There's a slight rash or an upset stomach. Is this a food allergy, which is an immune response to normally harmless substances? Or is it something quite different, such as lactose intolerance, where the body can't easily digest the natural sugar found in milk?
STALLINGS: The reason food allergy symptoms are often confused with other symptoms - for example, lactose intolerant - is because there really is an overlap in some of the symptoms.
AUBREY: Adding to the confusion, food allergies can be complicated to diagnose.
STALLINGS: We do not have an optimal diagnostic tool. There isn't one skin test or one blood test that allows you to say, yes, you definitely do or do not have an allergy to a specific food.
AUBREY: Stallings says if parents recognize clear signs of allergic reactions, such as swelling lips or difficulty breathing, they should seek emergency care, but oftentimes, the symptoms are much milder. So rather than self-diagnosing an allergy, Stallings says the best option is to see an allergist.
STALLINGS: The committee really does recommend that people seek more expert advice.
AUBREY: Bruce Lanser directs the pediatric food allergy program at National Jewish Health in Denver. He says lots of families do jump to conclusions before being tested.
BRUCE LANSER: We unfortunately see kids avoiding food unnecessarily because of some fear of a potential allergy.
AUBREY: He says skin tests are not completely accurate. Plenty of people test positive for a particular food, but then it turns out they can tolerate the food just fine. Lanser says the gold standard they use to diagnose a food allergy is a food challenge. Patients go to the allergist's office and are given small amounts of the food that they may be allergic to.
LANSER: We start with a small amount of food and slowly give increasing doses up to a full serving. And obviously, if we react at some point, we stop it and treat.
AUBREY: Lanser says he tests his patients every year to see if they've outgrown the allergy, which they often do. In fact, he says about one in five people outgrow their peanut allergy. Allison Aubrey, NPR News.
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