A new study from researchers at the University of Iowa reveals a link between food allergies and autism, though many questions remain.

The study showed 11.25 percent of American children diagnosed with autism spectrum disorder (ASD) also have a food allergy, more than double the 4.25 percent of kids without ASD who suffer from a food allergy.

“It is possible that the immunologic disruptions may have processes beginning early in life, which then influence brain development and social functioning, leading to the development of ASD,” Wei Bao, assistant professor of epidemiology at the UI College of Public Health and corresponding author of the study, told Iowa Now.

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The researchers analyzed health information from about 200,000 children, ages 3 to 17, that was compiled from 1997 to 2016 through the CDC’s U.S. National Health Interview Survey.

The results, which also showed that children with ASD were significantly more likely to have respiratory and skin allergies than kids without the condition, add to a growing body of research revealing links between immunological problems and ASD.

“This indicates there could be a shared mechanism linking different types of allergic conditions to ASD,” Bao told Iowa Now, adding that it’s still unclear how these conditions interact, or whether one causes the other. “We don’t know which comes first, food allergy or ASD.”

Bao said establishing a timeline showing how these conditions develop in children is crucial to answering that question.

“A future study that prospectively collect data on the timing of onset for food allergy and autism is needed to establish the temporal relationship between these two conditions,” Bao told the American Journal of Managed Care.

Past studies show that children are at higher risk of developing ASD if their families have a history of type 1 diabetes or (on the mom’s side) rheumatoid arthritis, or if the mother has immunological problems during pregnancy

The new study is limited by the fact that rates of both allergies and ASD have been on the rise in recent years, and the findings rely on self-reported data that don’t provide a long enough timeline from which to draw conclusions. In some cases, self-reported data on children with food allergies and ASD might not be reliable because it can be hard to differentiate between an allergic reaction and aberrant behavior that might be explained by another factor.

Some medical professionals say parents shouldn’t overreact to the new study. 

“I wouldn’t want people to misinterpret this to say that a food allergy is causing autism,” pediatric allergist Scott H. Sicherer at the Icahn School of Medicine at Mount Sinai in New York, told the American Journal of Managed Care.

The new study was published in JAMA Network Open.

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