The impact of microplastics (MPs) on the diversity and composition of the gut microbiome has been extensively documented in animal studies, but evidence in humans remains limited. Recognizing the potential differences in MP effects between animal and human gut microbiomes, this review synthesizes current evidence concerning their impact on the human gut microbiota. Furthermore, the potential links between microplastic-induced dysbiosis and the pathogenesis of human diseases were analyzed. Cross-sectional studies have been conducted to explore microplastic exposures (such as in humans who consume hot foods served in disposable plastic tableware) and their associations with gut microbiome functionalities in infants, preschool children and adults. Exposure to MPs increased the abundance of Dethiosulfovibrionaceae, Enterobacteriaceae, Moraxellaceae, Actinomycetota, Pseudomonadota, and Veillonella. On the other hand, MPs decreased the abundances of Bacillota, Bacteroidota, Lactobacillales, Rikenellaceae, Parabacteroides, Roseburia, Coprococcus, Turicibacter, and Eubacterium coprostanoligenes. These changes were associated with a decrease in butyrate production and a decrease in short-chain fatty acid levels. However, for some other bacteria, both inductive (on Oscillospiraceae, Adlercreutzia, Phascolarctobacterium, and Collinsella) and repressive effects (on Streptococcus) have been documented. There are contradictory reports about MP-induced changes in Lachnospiraceae (including the Dorea genus), Alistipes and Faecalibacterium, which may be correlated with obesity, gastrointestinal dysfunction, some cancers, inflammatory bowel disease and Crohn's disease. Potential reasons for these discrepancies are proposed. This review also examines putative mechanisms, with a focus on biofilm formation on selective surfaces, and discusses the inherent limitations of current MP exposure assessments in human gut microbiota studies.
Yang et al. (2026) studied this question.