These days, any parent worth her salt knows to inquire about food allergies before a playdate begins. Allergies are everywhere, to all sorts of nuts, or eggs, or dairy. Rustling up a snack has never been more complicated, as Andrew Liu learned when he was responsible for providing it in his child’s kindergarten class.
A pediatric allergist, Liu asked who was allergic and got a list of six names out of 28 students. “I thought, Could this really be?” says Liu, who practices at National Jewish Health in Denver. Over the course of the year, he became convinced. “These kids were having full-out allergic reactions. I came to believe anecdotally something had changed.” (More on Time.com: Figuring Out Food Labels)
That experience prompted Liu to try to quantify just who out there has food allergies. The National Institutes of Health funded him, and he recently published his results: About 2.5% of Americans — nearly 8 million — suffer from food allergies, and children suffer the most. (Not only are they hit hardest physiologically, but more than 30% of kids with food allergies report they’ve been bullied.) In the Journal of Allergy and Clinical Immunology, Liu reports that 4.2% of kids between the ages of 1 and 5 are allergic, a rate that dips slightly, to 3.7%, for children between the ages of 6 and 19. Black boys are 4.4 times as likely as other children to have food allergies. (The least allergic segment of the population? The over-60 crowd, at 1.3%.)
The dreaded allergy to peanuts — with its corresponding horror stories of anaphylactic shock — is found in 1.8% of children ages 1 to 5, and 2.7% of kids ages 6 to 19, according to the research. Just .3% of adults can’t tolerate the legume.
Liu’s is the first study to rely on an objective test to determine whether people are truly allergic or only think they are. He scrutinized immunoglobulin E (IgE) or antibody levels to determine whether common foods — including peanuts, milk, eggs, and shrimp — trigger allergic reactions. Food allergies occur when IgE antibodies are produced in response to a specific food protein. Once IgE antibody is present, future exposure to the trigger food sets off an allergic response. What’s particularly interesting is how the results dovetailed neatly with those of recent U.S. Centers for Disease Control and Prevention (CDC) research that simply asked people if they have a food allergy. (More on Time.com: Photos: From Farm to Fork)
When I was in school, I don’t remember any students being allergic to anything. But now there are peanut-free tables in the lunchroom and EpiPens are as ubiquitous as Sharpies in a teacher’s desk drawer. Even the ritual of shared snack has taken on a new dimension: Because of myriad and extensive food allergies among the gaggle of 5-year-olds in my daughter’s class, each child must come equipped with her own edible pick-me-up.
“Now there is better awareness,” says Liu, explaining that heightened consciousness can lead to more people realizing they have allergies. “But there is also a sense something has changed.”
Theories about the spike in food allergies abound, but they’re just that: theories. “We don’t really know,” says Liu, “and we’re realizing just how little we know about how it develops.”
Some experts believe early exposure to peanuts, for example, increases the likelihood of peanut allergy. (I remember asking my doctor about eating peanut butter while pregnant; he advised me that unless I had a family history of food allergy I should be okay — fortunate news considering that gestating made me crave peanut butter straight from the jar.) Others hypothesize that eating peanuts early on — as Israeli children do — helps develop resistance; researchers are studying this now. (More on Time.com: The ‘Other’ Salt: 5 Foods Rich in Potassium)
There also appears to be a link between food allergies and asthma. People with both are seven times more likely to end up in the emergency room with a severe asthma attack than those without food allergies.
For now, avoidance is the name of the game when it comes to preventing allergic reactions. But there’s intriguing progress at Johns Hopkins, where scientists have figured out how to shut down the immune system’s allergic reaction to some food proteins in mice. If the research, published online in the journal Nature Medicine, could be replicated in humans, it could represent a way to desensitize severely allergic people, who visit emergency rooms about 300,000 times a year. Up to 200 people die each year because of allergies to food.
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