In a study conducted by the University of Iowa of nearly 200,000 just children, children  with Autism Spectrum Disorder (ASD) were twice as likely to suffer from a food allergy than children who do not have ASD. Researchers analyzed health-related information from the children ages 3 to 17, which was compiled from 1997 to 2016 through the CDC’s U.S. National Health Interview Survey.

The study showed that 11.35% of American children diagnosed with ASD also have a food allergy, which is more than double the 4.25% of kids without ASD. Wei Bao, Assistant Professor of Epidemiology at the UI College of Public Health and the study’s corresponding author, says that the finding adds to the growing body of research that points to immunological dysfunction as a possible risk factor for the development of ASD.

Additionally, Bao reports, in an article with IowaNow that this study could not determine the causality of the relationship  given its observational nature, “We don’t know which comes first, food allergy or ASD”, suggesting that another longitudinal study of children since birth may be necessary in the future. However, previous studies have suggested possible links between food allergies and ASD, including immune system overreactions causing impaired brain function, neurodevelopmental abnormalities, increased production of antibodies, and alterations in the gut biome.

Bao also reports that previous studies on the association of allergic conditions with ASD focused mainly on respiratory allergy and skin allergy, and those studies yielded inconsistent and inconclusive results.  The new study conducted by Bao and  his team found 18.73 percent of children with ASD suffered from respiratory allergies, compared to only 12.08 percent of children without ASD; and 16.81 percent of children with ASD had skin allergies, compared to 9.84 percent of children without ASD.

Bao says, “This indicates there could be a shared mechanism linking different types of allergic conditions to ASD.”

However, according to Bao, the study may be limited because the NHIS depends on respondents to voluntarily self-report conditions, meaning the number of children with ASD or allergies may be misreported by those taking the survey. Either way, this study reveals an important new link into the study of Autism.

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