Micro- and Nanoplastics: A Paradigm Shift in the Pathogenesis of Inflammatory Bowel Disease

Micro- and nanoplastics (MNPs) are pervasive environmental contaminants with growing recognition as potential contributors to human disease. Widespread human exposure occurs primarily through ingestion of contaminated food and water, and MNPs have been detected in multiple human tissues, including the gastrointestinal tract. Experimental evidence provides a plausible biological basis for disease associations, including impairment of intestinal barrier integrity, activation of mucosal immune pathways, and alteration of gut microbial communities caused by MNP exposure. Although human data remain limited, early studies demonstrate MNP detection in stool and suggest potential correlations with inflammatory biomarkers such as fecal calprotectin. These findings, together with mechanistic data from in vitro and animal models, raise concern that MNP exposure represents a paradigm shift in the pathogenesis or modulation of inflammatory bowel disease (IBD); however, methodological variability, small sample sizes, and contamination challenges currently limit definitive conclusions. The aim of this review is to evaluate the current understanding of MNP exposure and its impact on intestinal health, particularly in relation to IBD. We synthesize mechanistic and early clinical evidence linking MNPs to IBD and highlight critical research gaps. Future standardized exposure assessment, mechanistic validation in human systems, and longitudinal studies are essential to clarify causal relationships. Given the modifiable nature of environmental plastic exposure, advancing this field may offer new opportunities for IBD prevention and intervention.