The Gut Microbiome in Foodborne Microplastic Toxicity: Mechanistic Insights and Human Health Risk Assessment

Microplastics (MPs) are emerging foodborne contaminants with increasing implications for gastrointestinal health. However, the mechanistic basis linking dietary MP exposure to gut dysbiosis and intestinal dysfunction remains poorly resolved, limiting robust human health risk assessment. This review critically synthesizes current evidence on foodborne MPs, dietary exposure, and the physicochemical determinants of gastrointestinal fate, bioavailability, and toxicity. We examine the molecular and microbiome-mediated mechanisms linking MPs exposure to intestinal dysbiosis, barrier dysfunction, oxidative stress, immune activation, and metabolic reprogramming. Particular attention is given to the role of MPs as vectors for co-contaminants, which can amplify toxicity through synergistic interactions and reshape host-microbiome responses. We highlight advances in dynamic colon simulation and integrated multi-omics that unravels the mechanism underlying MP-induced intestinal toxicity. Current evidence indicates that gut microbiome dysregulation is a key mechanism driving foodborne MP-induced intestinal dysfunction and systemic toxicity. This review integrates multidisciplinary evidence to identify critical knowledge gaps and guide future research on the mechanisms, exposure, and health risks of foodborne microplastics.