A new animal study suggests that the microscopic plastic particles showing up in food and drink could have a surprising impact on health — specifically, on metabolism and liver function.
Researchers at the University of California, Davis, found that mice fed polystyrene nanoplastics experienced changes in blood sugar regulation, signs of liver injury and increased gut permeability. The findings were presented at the 2025 annual meeting of the American Society for Nutrition.
Nanoplastics are particles smaller than 100 nanometers and can form as plastic packaging breaks down. Over time, these particles enter the food chain through seafood, bottled water and even processed foods. Some estimates suggest people may consume tens of thousands of these particles every year.
“With the growing concern around micro- and nanoplastic exposure, we wanted to evaluate the impact of this exposure on health,” said lead researcher Amy Parkhurst, a doctoral candidate at UC Davis. “Our observations that oral ingestion of polystyrene nanoplastics contributes to glucose intolerance and signs of liver injury confirm and extend what has been recently reported on the effects of nanoplastics in animal models.”
In the study, mice were fed standard chow along with a daily dose of polystyrene nanoparticles, commonly found in food packaging. Compared to a control group, these mice showed signs of liver stress and impaired glucose control, both indicators that plastic exposure may disrupt metabolic function.
While this was a small animal study and not yet peer-reviewed, the findings add to a growing body of evidence about the potential risks of plastic exposure through food. The researchers emphasize the need for more studies to better understand how these particles affect the body and to help guide future public health policy.
This project was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.