Figure 1.

Four microbiome-based aging clocks. Age-related decline in gut microbiome biodiversity can be used to determine biological age. Certain species are enriched in different individuals and relate to the biological clock; for example, A. muciniphila is enriched in centenarians and is associated with longevity, while C. jejuni is enriched in individuals with higher biological age. Metagenomic and metatranscriptomic analysis gives insights into microbiome functions that affect host aging. Metametabolomics of blood, urine, or stool can identify microbiome-derived metabolites associated with biological age. SCFA: short-chain fatty acids. Figure created with BioRender (biorender.com).