Tongue Age: A New Dimension for Disease Risk Assessment Based on Tongue-coating Microbiome and Imaging Features

Tongue examination has been used in Traditional Chinese Medicine to assess overall health status from observable tongue phenotypes. With the in-depth integration of microbiome profiling and digital imaging technology, tongue coating, an important colonization interface for oral microorganisms, has provided a new perspective for the early risk detection of major diseases through the quantitative analysis of the microbiome and image features. This study proposes "tongue age” as an indicator reflecting the degree of biological aging of the body, evaluated by integrating tongue-coating microbiome profiling and tongue imaging phenotypes, which are distinct from chronological age. We outlined the definition and quantitative evaluation framework for tongue age, discussed its potential utility for cardiovascular disease risk stratification and longitudinal monitoring, and summarized the key challenges and future directions for standardization, validation, and clinical translation.