Can Micro- and Nanoplastics Modify Food-Allergy-Relevant Pathways?-A Comprehensive Narrative Review

Micro- and nanoplastics (MNPs) are widely detected in food, drinking water, food-contact materials, and human biological samples. This narrative review evaluates whether experimental evidence supports a role for MNPs as modifiers of food-allergen digestion, intestinal-barrier function, microbiota composition, and immune tolerance. In vitro studies indicate that protein-corona formation can alter allergen conformation, epitope accessibility, and proteolysis, although effects vary by polymer, particle size, dose, and digestive model. Rodent studies provide evidence that MNP exposure can disrupt epithelial integrity, induce oxidative and inflammatory signaling, and modify microbiota-dependent immune regulation. More direct food-allergy models have reported exacerbation of ovalbumin- and cow's-milk-allergic responses, including Th2 polarization and changes in dendritic cell and regulatory T-cell compartments. Infants may represent a susceptible and highly exposed population because of immature digestive and barrier function and the use of plastic feeding equipment; however, the available pediatric evidence is limited to exposure studies and simulated digestion. The effect of MNP exposure on the incidence of food allergies, reaction thresholds, or clinical severity in humans has not yet been studied. Accordingly, current findings support biological plausibility and identify research priorities, but they do not establish causality in humans.