If you have children, you know that protecting them against food allergies is a big concern these days. Such a big concern that doctors recommend treatment against allergies start in utero. (Current research suggests expectant mothers load up on peanuts five times a week or more during pregnancy in order to prevent the very common peanut allergy.)
In total, there are eight “big” food allergies that parents and doctors look out for, according to FARE, the Food Allergy Research & Education organization: peanuts, tree nuts, milk, eggs, wheat, soy, fish, and shellfish. Some, like milk, eggs, and wheat, are commonly shed in childhood. But others, like peanuts, tend to stick around.
But while most of the allergy research in the United States has focused on how it affects children (approximately eight percent of children deal with food allergies, compared to five percent of adults), researchers have spent years parsing together anecdotal evidence of another issue altogether: adult-onset food allergies.
Until recently, researchers knew little about the true prevalence of adult food allergies, but thanks to the data collected by a new national study, we now know that more than half of adults in the US with food allergies got them after they turned 18. For adults, shellfish is the most common allergen (3.9 percent), followed by peanuts (2.4 percent), and tree nuts (1.9 percent)
In a representative sample of 40,447 adults across the US, nearly 52 percent of subjects fell victim to what the paper’s lead researcher, pediatrician and allergy specialist Dr. Ruchi Gupta, calls the “turn-on switch.” What’s more, adults appear to have unique methods of developing allergies that children don’t, such as oral allergy syndrome (OAS), which makes your throat or mouth itchy when eating certain types of produce, mostly fruit. As Dr. Sharon Chinthrajah, an allergy researcher involved in the study, explained to The New York Times, oral allergy syndrome typically affects adult sufferers of seasonal allergies and “involves your body getting tricked” by the similarity in protein structures between allergens. For instance, someone with an allergy to birch tree pollen might develop an allergic reaction when they eat certain fruits, like cherries, peaches, and apples, simply because the proteins are structurally similar—though OAS is not the same thing as a true food allergy, which may be life-threatening. Chinthrajah also notes a key distinction between food allergies and food intolerance, the latter of which is not as well-understood. Allergic reactions show up within two hours of eating the offending food, while symptoms of food intolerance show up the next day.
I can, unfortunately, attest to the very real phenomenon of adult-onset allergies, which I suddenly had to apples, peaches, and citrus fruit right after college. If the same is true for any of you, take heart. Although you should stay away from any allergy-inducing produce in their raw form, you can, in some cases, eliminate an OAS reaction by cooking or processing the fruit in question, which sometimes (if you're lucky!) denatures the triggering protein. Bake, jam, and jelly your heart out!