Exploring the Connection Between Gut Health and Autism

Rising Autism Rates and Unknown Causes

A recent article published in Nature has delved into the relationship between gut health and autism. Over the past two decades, the prevalence of autism among children in North America has surged, yet the definitive causes of the disorder remain unclear. Researchers have traditionally attributed autism to a mix of genetic and environmental influences. However, emerging studies suggest a potential connection to gut health.

Microorganisms and Their Impact

Certain microorganisms, such as Clostridia spp. and Bacteroidetes, are present in higher levels in the intestines of children diagnosed with autism compared to their neurotypical peers. A significant by-product of digestion by these microbes is propionic acid, an acid frequently utilized as a preservative in processed foods. While propionic acid naturally occurs in the body and plays a role in regulating various internal functions, excessive amounts can lead to negative outcomes, including developmental delays.

The Hypothesis of Maternal Gut Health

Researchers propose that elevated levels of propionic acid in a mother’s gut, potentially due to high consumption of processed foods, might be transferred to the fetus’s bloodstream, influencing their neural development. To investigate the connection between gut health and autism, researchers conducted experiments analyzing the growth patterns of in-vitro neural stem cells treated with propionic acid.

Experimental Findings on Neural Stem Cells

In their experiments, researchers treated neural stem cells with either propionic acid, butyric acid (another by-product of microbial digestion linked to autism), or a control substance. Typically, neural stem cells differentiate into neuroepithelial progenitor cells, which can then develop into glial cells or neurons. Glial cells play a crucial role in protecting neurons and supplying them with essential nutrients. The cells were incubated, and the researchers measured the sizes of the resulting neural stem cell clusters, along with gene expression and protein levels in the neural cells.

Effects of Propionic Acid on Glial Cell Production

The study revealed that propionic acid significantly increased the production of glial cells and elevated levels of glial fibrillary acidic protein, which supports neural activity and protects neurons while inhibiting neuron production. Additionally, the treatment with propionic acid resulted in higher concentrations of inflammatory compounds compared to the butyric acid and control groups.

The Implications of Glial Cell Overproduction

Although glial cells contribute positively to neural health, their overproduction can be harmful. This alteration in neural composition may disrupt normal neural pathways and hinder effective communication within the brain, potentially leading to some symptoms commonly associated with autism. Given the influence of a mother’s gut microbiome on fetal health, further research is needed to examine the relationship between processed food consumption, propionic acid production in mothers, and neural development in their fetuses.

Reference

Naatey-Ahumah, M. (BSc). Abdelli, L.S., Samsam, A., & Naser, S.A. (2019). Propionic Acid Induces Gliosis and Neuroinflammation through Modulation of PTEN/AKT Pathway in Autism Spectrum Disorder. Scientific Reports, 9. https://doi.org/10.1038/s41598-019-45348-z

Image by mohamed Hassan from Pixabay