A collaborative US and Chinese study has found that the microbial communities present on our skin and in our mouths can predict your age, within a margin of several years. Additionally, they found a loss of key bacterial species in older participants, suggesting a potential anti-aging target.

It’s well recognised that the human gut microbiome changes over the course of one’s lifetime. For example, many active studies are investigating how environmental factors affect the microbial species present during pre- and postnatal development. This study sought to establish whether the microbial patterns observed in the gut were in concordance with our other microbiomes; the epidermal and oral.

The researchers analysed over 9,000 samples collected from the hands, forehead, mouth and stool samples from people aged between 18 and 90. No participants had taken antibiotics in the preceding month as that would diminish bacterial colonies in the gut. They then applied a machine learning approach called random forest regression to associate relative microbial abundances with individual age. Interestingly, they found the skin microbiome to be the most reliable predictor of age, doing so to within an average of 3.8 years. This out-performed the oral and gut samples as indicators, with leeway averages of 4.5 and 11.5 years, respectively. 

Secondly, the group examined the species present and their relative abundances against individual age, in all three microbiome environments. Results showed significant taxa to be less abundant in individuals over 30 years old, but only in the oral and gut microbes. The differences in microbial compositions they said indicated age-associated changes. Decreased sebum production and increased dryness, as well as immunological changes are typical signs of skin aging and likely determine the bacterial abundances, researchers say.

They went on to comment that future research should investigate how the microbiome might accelerate or decelerate the aging process, and “enable potential microbiome-targeted therapeutic strategies to prevent aging”.