Processed food: Key reason for rise in autism

Washington: According to a recent study, processed foods may hold key to rise in autism. With the number of children diagnosed with autism on the rise, the need to find what causes the disorder becomes more urgent every day. With the findings of this study, researchers suggest that they are now a step closer to showing the link between the food pregnant women consume and the effects on a fetus' developing brain.

As part of the study, a team of researchers identified the molecular changes that happen when neuro stem cells are exposed to high levels of an acid commonly found in processed foods. In the study published June 19 in Scientific Reports, a Nature journal, the scientists discovered how high levels of Propionic Acid (PPA), used to increase the shelf life of packaged foods and inhibit mold in commercially processed cheese and bread, reduce the development of neurons in fetal brains.

Saleh Naser, who specialises in gastroenterology research at the College of Medicine's Burnett School of Biomedical Sciences, began the study after reports showed that autistic children often suffer from gastric issues such as irritable bowel syndrome. He wondered about a possible link between the gut and the brain and began examining how the microbiome or gut bacteria differed between people with autism and those who do not have the condition.

"Studies have shown a higher level of PPA in stool samples from children with autism and the gut microbiome in autistic children is different. I wanted to know what the underlying cause was," Naser explained.

In the lab, the scientists found exposing neural stem cells to excessive PPA damages brain cells in several ways. First, the acid disrupts the natural balance between brain cells by reducing the number of neurons and over-producing glial cells.

While glial cells help develop and protect neuron function, too many glia cells disturb connectivity between neurons. They also cause inflammation, which has been noted in the brains of autistic children.

Excessive amounts of the acid also shorten and damage pathways that neurons use to communicate with the rest of the body. The combination of reduced neurons and damaged pathways impede the brain's ability to communicate, resulting in behaviours that are often found in children with autism, including repetitive behaviour, mobility issues and inability to interact with others.