Why Are Peanut Allergies on the Rise?

Typically, the immune system treats peanuts as safe, but some scientists believe that early and heavy exposure to peanutladen products might cause the immune system to misidentify them as dangerous. This theory is strengthened by the fact that 8 out of 10 allergic kids have a reaction the first time they eat a peanut, indicating a previous indirect exposure, possibly even in the womb or through breast milk. Theories about peanut allergies abound and most involve an overactive immune system. “We have done such a good job of eliminating the threats that the immune system is supposed to manage that it’s looking for something to do,” says Anne Muñoz-Furlong, former CEO of the nonprofit Food Allergy and Anaphylaxis Network. Parents today feed their kids a lot of ready-made snacks, many of which contain peanuts or their derivatives.

“We’re bombarding the immune system with these [food-based] allergens, so it’s attacking those instead.” Indeed, food allergies in general are on the rise. But peanuts seem to trigger especially violent immune reactions. This might be because they contain several proteins not found in most other foods, posits Robert Wood, an allergy specialist at Johns Hopkins University, and the structure of these proteins can stimulate a strong immune response. Research suggests that roasting peanuts, as American companies do, might alter the proteins’ shape, making them an even bigger target. Allergy rates are lower in China, where it’s customary to boil peanuts, which damages the proteins less. (It’s worth noting, though, that China is also more polluted, so people’s immune systems might be concentrating on traditional threats.) Or maybe it’s all the time indoors. Children who spend little time outdoors tend to be deficient in D, Wood says, so their bodies might mislabel peanut proteins as dangerous. Parents looking to protect their kids might consider sending them outside—and not washing their hands when they come home.

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