Even though there is no scientific evidence supporting the idea that a gluten-free diet can mitigate the symptoms of autism spectrum disorders (ASD), many parents and people with ASD have espoused gluten-free diets like those of people with celiac disease. This treatment most likely stems from the theory that autism is caused by problems with the digestive system, which in turn is related to the fact that many people with ASD have significant gastrointestinal problems. However, new research strongly suggests that there is no connection between ASD and celiac disease, despite popular belief.

This study is based on health records data from Sweden. The country not only has relatively high rates of celiac disease, but it also has a robust health record system, making it an ideal target for research of this nature. First, the research team gathered data from 290,000 people who had internal biopsies—the most reliable way to test for celiac disease—on their record. They found that approximately 27,000 people had celiac disease and another 15,700 had some kind of celiac-like inflammation. The remaining 213,000 had no traces of celiac disease.

Next, the researchers tallied up the number of people with ASD in both the celiac-having and celiac-free groups. Individuals in both groups were age- and sex-matched to each other. The researchers were also careful to compare only those people who had internal biopsies in the same year and who lived in the same region of Sweden.

The results showed no evidence of a relationship between ASD and celiac disease. However, they did find that in a smaller subset of children, a diagnosis of celiac disease increased the odds of being diagnosed with autism later on by around 40 percent.

“If there was a connection between these two diseases—either hidden celiac disease causing autism or autism causing celiac disease, it should have shown up in the study of this size. So, I think that’s the big message. This brings some finality to that debate,” said Dr. Joseph Murray, celiac specialist at the Rochester, Minnesota Mayo Clinic.

This study is published in the journal JAMA Psychiatry.

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