The findings were presented at NUTRITION 2025, the flagship annual conference of the American Society for Nutrition, currently underway in Orlando, Florida
Microscopic plastic particles commonly found in food and beverages could impair liver function and glucose metabolism, according to a new animal study raising red flags over potential health risks linked to plastic consumption.
The research focused on microplastics (less than 5 millimetres) and nanoplastics (less than 100 nanometres), which can enter the human body through contaminated seafood, food packaging, and bottled drinks. Estimates suggest that an average person may ingest between 40,000 and 50,000 microplastic particles annually, with some studies placing the number closer to 10 million.
“Our observations that oral ingestion of polystyrene nanoplastics contributes to glucose intolerance and signs of liver injury confirm and extend recent findings in animal models,” said Amy Parkhurst, a doctoral candidate at the University of California, Davis, US, and lead author of the study.
To mimic human exposure, researchers administered a daily oral dose of polystyrene nanoparticles—commonly found in food containers and packaging—to 12-week-old male mice. The dose was set at 60 mg per kilogram of body weight, based on earlier studies showing similar health effects at this level.
While all laboratory animals may be exposed to environmental plastics, Parkhurst noted that the study was designed to measure dose-correlated changes. The mice receiving the nanoparticle dose demonstrated systemic glucose intolerance, a precursor to metabolic disorders, as well as elevated levels of alanine aminotransferase (ALT), an enzyme indicating liver injury.
Researchers also found evidence of increased gut permeability and elevated endotoxin levels, both of which can contribute to liver dysfunction and systemic inflammation.
“We can’t control for all the plastics the mice are exposed to,” said Parkhurst. “However, our controlled dosing helped isolate the effects of nanoplastics more clearly.”
The findings were presented at NUTRITION 2025, the flagship annual conference of the American Society for Nutrition, currently underway in Orlando, Florida. Parkhurst emphasized that while the study was conducted in animals, the results suggest an urgent need to further investigate the human health implications of plastic ingestion.
“Robust scientific evidence plays a key role in shaping monitoring efforts and guiding regulations. Our findings warrant further studies to help inform policy around micro- and nanoplastics,” she said.
