Could there be a link between autism and food allergies? A new study from the University of Iowa suggests one, but researchers are still trying to discover how and why.

The study, published recently, found that children with autism are more than twice as likely to experience a food allergy than children who do not have ASD.

Researchers analyzed the health information of nearly 200,000 children between the ages of 3 and 17 collected by the U.S. National Health Interview Survey, an annual Centers for Disease Control and Prevention survey of American households. The data covered 1997 to 2016.

The study found that 11.25 percent of children reportedly diagnosed with ASD have a food allergy, compared with the 4.25 percent of children who are not diagnosed with ASD and have a food allergy.

The findings, researchers said, add to a growing body of research that already suggests immunological problems as a possible risk factor for developing autism.

Because the study is observational, though, researchers couldn’t identify a cause-and-effect relationship between food allergies and autism. We don’t know which comes first, food allergy or ASD, the researchers concluded.