Frontiers in Cellular and Infection Microbiology · Oct 30, 2026
Green tea polyphenols and microbial metabolites at the oral–epigenetic–immune interface: Implications for inflammaging and neurodegeneration
By Juan Liu, Cheng Zhong, Hua Yin et al.
Green tea polyphenols, especially epigallocatechin-3-gallate (EGCG), have drawn substantial attention due to their antimicrobial, anti-inflammatory, antioxidant, and possible epigenetic effects. Nonetheless, the biological actions of green tea may not stem exclusively from the parent catechins, because a significant fraction is transformed by microbes into low-molecular-weight metabolites that exhibit distinct bioavailability and biological characteristics. This review explores the emerging interface among green tea polyphenols, their microbial metabolites, the oral microbiome, epigenetic regulation, and immune signaling, with a particular focus on potential associations between oral dysbiosis, inflammaging, neurodegeneration, and age-related diseases. We first summarize the bioavailability and microbial transformation of the principal green tea catechins, and then assess their possible effects on oral microbial communities, pathogenicity, biofilm formation, and host–microbe interactions. We also evaluate evidence that links catechins and their metabolites to inflammatory pathways, epigenetic mechanisms, cellular senescence, and immune regulation. The available evidence indicates that green tea polyphenols may affect the oral microbial ecosystem and inflammatory signaling, whereas microbial metabolites may help explain some systemic biological effects linked to green tea intake. These influences could reasonably converge with pathways associated with inflammaging and neuroinflammation. Throughout, demonstrated mechanisms are distinguished from proposed links and from supraphysiological experimental exposures. However, there is still limited human evidence directly confirming a causal oral microbiome–metabolite–epigenetic–immune pathway. Accordingly, future longitudinal, multi-omics investigations that combine oral microbiome profiling, metabolomics, epigenomics, and immune phenotyping are required to assess whether these mechanistic relationships lead to clinically relevant impacts on healthy aging and age-related disease.