Microplastics may spread from gut to brain, finds study

Microplastics, found in various substances, are ubiquitous in the environment, from soil to food and water. Upon ingestion, they traverse the digestive tract and can enter the bloodstream through the gut lining. These particles can circulate throughout the body, potentially reaching the blood-brain barrier, which normally shields the brain from harmful substances. Under certain conditions, smaller microplastic particles may breach this barrier, accumulate, and possibly induce adverse effects.

In the study, researchers sought to understand the impact of different types of microplastics on various organs in mice. They defined microplastics as plastic particles smaller than 5 millimeters and aimed to replicate human exposure levels. Mice were orally fed varying amounts of polystyrene or mixed polymer microspheres. After ingestion, the researchers examined serum, brain, liver, kidney, and colon tissues to assess the presence of microplastics and any resulting effects.

The results showed microplastics in multiple organs including the brain, liver, and kidneys of exposed mice. These findings show how microplastics are capable of spreading to other, distant areas of the body. After microplastic exposure, they also found that specific metabolic changes occurred in the colon, liver, and brain. These changes depended on how much exposure the mice received and what type of microplastic they were exposed to.

“Previous research from our group has demonstrated that microplastics can disrupt immune function. This could be a problem when dealing with infections or could possibly worsen conditions like inflammatory bowel diseases. Additionally, our study was performed over a 4-week period, showing significant alterations in metabolism. This brings insight into the long-term accumulation of microplastics in the body, raising concerns about chronic exposure. Furthermore, our study revealed substantial metabolic alterations linked to various metabolic and immune disorders, including changes in amino acid, lipid, and hormone metabolism,” said study author Marcus Garcia, postdoctoral fellow at the University of New Mexico College of Pharmacy.

Reference: Marcus M. Garcia, Aaron S. Romero, Seth D. Merkley, et al,; In Vivo Tissue Distribution of Polystyrene or Mixed Polymer Microspheres and Metabolomic Analysis after Oral Exposure in Mice; Environmental Health Perspectives; https://doi.org/10.1289/EHP13435