Researchers from the University of Central Florida (UCF) just announced intriguing findings which describe cellular changes that develop when neuronal stem cells are exposed to elevated levels of a chemical typically found in processed foods.

The study serves as an example of the importance of the food pregnant women eat, and how it may potentially affect development of the fetal brain.

The study describes how elevated levels of the preservative, propionic acid (PPA)-used to extend shelf life and reduce mold in packaged foods, breads and cheeses โ€” can adversely affect the development and differentiation of neurons in fetal brains in children with autism spectrum disorder (ASD).

The research was published June 19 in the journal, Scientific Reports.

The Gut-Brain Axis

From clinical experience, healthcare providers have observed for many decades how children with ASD are often afflicted with gastrointestinal ailments, including chronic constipation and irritable bowel syndrome (IBS). The mechanism behind this association is unclear, but ongoing research suggests that the gut microbiome plays an important role in brain development. One of the key questions is how the gut microbiome--the bacteria that live in our intestines--may be unique in those with ASD compared to those without the condition.

Previous studies have demonstrated increased levels of PPA, a short chain fatty acid (SCFA), in the feces of children with ASD; we also know that the gut microbiome in these children is also quite distinct in terms of the type of bacteria that inhabit their intestines.

Clostridia, Bacteriodetes, and Desulfovibrio bacteria are unique to patients with ASD. What's interesting is that these bacteria are also known to be fermenters of carbohydrates that produce PPA, and other SCFAs as well. Ironically, while PPA is the most common compound produced by bacteria in ASD patients, it is also widely used in the food industry as a preservative due to its ability to inhibit grown of fungi (mold).

The Study

In the current study, Saleh Naser, PhD and her team at UCF found that when neural stem cells were exposed to high levels of PPA, the neurons incurred multiple changes resulting in cellular damage and inflammation. One of the major effects of PPA they noted was the overproduction of glial cells , the protective outer cells making up the sheath covering neurons, with a corresponding reduction in the number of neurons themselves. An excess of glial cells may disrupt the connectivity between the neurons and induce inflammation, a common finding in the brains of children with ASD.

While prior studies have suggested the role of genetic factors and environmental influence in ASD, this study, according to the authors, is the first to note a molecular link from elevated levels of PPA, overproduction of glial cells, disruption of neural connections and autism.

PPA is also felt to be a contributor to mitochondrial dysfunction, based on studies in rats exposed to PPA. In fact, nearly a third of ASD patients are felt to have mitochondrial dysfunction .

It also should be noted that PPA is naturally found in the gut, but consumption of processed foods by pregnant women containing PPA may increase maternal levels which are then transmitted to the fetus.

The team's research is preliminary and will require validation in ongoing studies to confirm if this mechanism explains at least part of the significant rise seen in autism rates from the early 2000's to the present. Autism spectrum disorders currently affect about 1 in 59 children, a sharp increase from 1 in 150 children seen in 2000, according to recent data from the CDC.

Naser and her team will attempt to validate the findings in a mouse model by examining whether elevated levels of PPA in the maternal diet induce behavioral changes consistent with autism in mice that are genetically predisposed to develop the condition.