Researchers from the University of Central Florida (UCF) College of Medicine in Orlando found that high levels of propionic acid (PPA) -- used in processed foods to extend shelf life -- change nervous system development in the fetal brain.
The study links maternal PPA exposure to "possible precursors for autism," say the researchers, who were led by Saleh Naser, PhD.
"This is an intriguing finding and a first in the field," they add, cautioning that much more research is needed.
The study was published online June 19 in Scientific Reports.
"There are good reasons to suggest the gut-brain axis is a potential culprit” in autism disorders, the researchers point out.
Naser told Medscape Medical News he was interested in understanding why children with autism disorders often get gastrointestinal disease. He says he was "intrigued" by reports that linked digestive system problems and higher levels of PPA in stool samples from children with the disorder.
"I wanted to know more about the role of the microbiome and GI disorders, if any, with brain development," he said.
In laboratory experiments, the UCF team found that exposing human fetal nervous system stem cells to high PPA levels disrupted the natural balance between brain cells by cutting the number of cells that change into neurons and by boosting the number that become glial cells, which are key parts of the nervous system.
Although glial cells help develop and protect neurons, if there are too many glial cells, they might affect the connection between neurons and cause inflammation, which was seen in the brains of children with ASD.
"The combination of reduced neurons and damaged pathways impede the brain's ability to communicate, resulting in behaviors that are often found in children with autism, including repetitive behavior, mobility issues, and inability to interact with others," the investigators say in a news release.
Previous studies have proposed links between autism and the environment and genes, but the UCF researchers note that their study is the first to show a link between high levels of PPA, the growth of glial cells, disturbed nervous system functions, and autism.
The researchers hope to repeat the findings in mice and to study whether a high-PPA maternal diet leads to offspring with ASD-like behavior.