Which of These Foods Might Suddenly Kill You?

Adult-onset food allergies are on the rise and can make your life miserable-or worse. Here's what's happening behind the scenes and how to deal with it.

- By Matt Jancer

MARTY SPARGO was in his early 20s when a marshmallow almost killed him.

He was on break from college with his friends, and they'd ducked away to the beach for a bonfire with roasted jumbo marshmallows. A few minutes after he gobbled one down, Spargo began to feel funny. My chest started getting heavy, and my heart was pounding so hard, and my vision was starting to distort, he says. Panic set in among the group as Spargo grew dizzier and dizzier and seemed on the verge of losing consciousness. His friends frantically called the hospital, carried him to the car, and rushed him to the emergency room. Spargo's diagnosis: He had a previously undiagnosed and possibly late-developing allergy to gelatin, which marshmallows are loaded with.

Although childhood food allergies get all the attention, adult-onset food allergies have become a thing, too. A recent report in The Journal of Allergy and Clinical Immunology: In Practice suggests there are more adults in the U. S. with a food allergy than children. While many adult allergies are continuations from child- hood, nearly half of the adults in this report said theirs started in adulthood. And it's only getting worse: Almost every allergy expert agrees that there's been a rise in the number of people in the U.S. reporting food allergies, says Scott Sicherer, M.D., one of that paper's authors.

It's not clear why foods you used to eat cause trouble for you now, and researchers also don't yet know why more and more adults are affected by food allergies. A combination of factors is likely to be responsible. It's not just genetics. It's not just the environment. It's not just the food we eat, says Bruce Roberts, Ph.D., research strategy and innovation officer at Food Allergy Research & Education.