According to popular theory, the presence of leaky gut syndrome may contribute to the development or symptoms of autism. However, a study published in the Journal of Pediatric Gastroenterology and Nutrition(JPGN) says that children with autism have no unique pattern of abnormal results on endoscopy or other tests for gastrointestinal (GI) disorders, compared to non-autistic children with GI symptoms, reports
The researchers analyzed the results of diagnostic tests in 61 children with autism being evaluated for GI symptoms, such as abdominal pain or constipation. The findings were compared with those in 50 non-autistic, or “neurotypical,” children undergoing similar tests. All tests were performed as part of routine clinical care–not solely for the purposes of the study.
The study focused on certain abnormalities with previously suggested links to autism. These include intestinal inflammation; deficiency of the digestive enzyme lactase, associated with lactose intolerance; and increased intestinal permeability, aka “leaky gut.”
Markers of intestinal inflammation, lactase deficiency, and intestinal permeability were all similar between the children with and without autism.
“The results of this study suggest that common gastrointestinal problems occur in children with autism and should be evaluated,” according to the authors. They add, “There is no evidence to support that gastrointestinal disorders cause autism.”
Previous studies, however, have found links between gut function and autism.
A 2015 study published in the journal Nutrition looked at a small group of children and found that those with autism spectrum disorder had lower counts of short-chain fatty acids, a type of anti-inflammatory fatty acid created by bacteria in the gut. This study had similar findings.
This recent study found that digestive enzymes were able to help decrease certain symptoms of ASD.
Other studies have found differences in the makeup of gut bacteria in children on the ASD.
So, while the recent study may say that there is no link between autism and gut health, we have to look at the parameters used in the study and the entire body of evidence. While those with autism may not have visible intestinal inflammatory markers, lactase deficiency, or increased intestinal permeability, the actual makeup of bacteria in the gut may differ, affecting the production of short-chain fatty acids (among other things) which may create an inflammatory pathway in the body that affects the brain. More studies need to be done to either confirm or deny the link.