Environmental Micro- and Nanoplastics and Metabolic Dysfunction-Associated Steatotic Liver Disease: A Current Review

The widespread use of plastics has increased environmental contamination with micro- and nanoplastics (MNPs), raising concerns about their potential health effects. Lifelong human exposure occurs mainly through ingestion and inhalation and begins from the prenatal period. Human exposure is very difficult to determine, due to the diversity of MNPs in the environment. Metabolic dysfunction-associated steatotic liver disease (MASLD), the most common chronic liver disease worldwide with increased prevalence, is strongly influenced by lifestyle and environmental factors. This review summarizes current evidence linking MNP exposure with MASLD. Experimental studies indicate that MNPs may alter the gut microbiota and intestinal barrier integrity, and following translocation across the intestinal barrier accumulate in hepatic and adipose tissues. Then, they may promote oxidative stress, inflammation, mitochondrial dysfunction, ferroptosis, immune dysregulation, and disturbance in lipid and glucose metabolism. Animal and in vitro studies show that these mechanisms may promote hepatic steatosis, inflammation and fibrosis, particularly in the presence of a high-fat diet. Although human evidence remains limited, the detection of plastic particles in blood and liver tissue supports biological plausibility. Further mechanistic, epidemiological, and clinical studies are needed to clarify whether MNPs contribute to MASLD development and progression.