Gut barrier breach and glucose dysregulation: the dual threat of food-transformed microplastics.

The widespread presence of polyethylene terephthalate microplastics (PET-MPs) in the environment raises concerns about their potential health impacts, which undergo complex physicochemical transformations during gastrointestinal digestion, yet how these alterations modulate their intestinal toxicity remains poorly understood. Here, employing a simulated digestion simulator coupled with an intestinal epithelial model, we demonstrate that PET-MPs, derived from commercial water bottles, experience extensive surface modification and biocorona formation in the digestive tract. The presence of a starch food matrix markedly accelerates these transformations, leading to increased particle aggregation and altered surface charge. These modified PET-MPs trigger a biphasic disruption of intestinal barrier function, characterized by an initial acute mucosal defense phase (neutral mucin hypersecretion) that is rapidly overwhelmed by sustained particle burden, transitioning into a secondary structural breakdown phase marked by severe oxidative stress, loss of epithelial integrity, and cytotoxicity. Furthermore, digested PET-MPs enhance the bioaccessibility and glucose transportation, potentially elevating systemic glycemic exposure. Our findings reveal that food matrix-driven transformations critically dictate the gastrointestinal fate and toxicity of microplastics, highlighting a previously underappreciated pathway through which dietary microplastics may compromise intestinal homeostasis and nutrient metabolism.