How old does your skin say you are? What sounds like the beginning of a cosmetics ad could soon be an actual diagnostic test, thanks to research on how microbiomes in and on the human body change with age (mSystems 2020, DOI: 10.1128/mSystems.00630-19).
Scientists have already found evidence that the human gut microbiome changes over time. A team led by Rob Knight and Zhenjiang Zech Xu at the University of California San Diego wanted to know if the same were true of other microbiomes—and if so, whether data about their composition could be used to more accurately predict a person’s age than using the gut microbiome.
To find out, they collected DNA sequence data from several different studies on the skin, oral, and gut microbiomes of healthy volunteers in different countries, including the US, the UK, China, and Tanzania. They then used machine learning to find correlations between those sequences and participants’ ages, which ranged from 18 to 90 years old. The most accurate predictions turned out to be based on the skin biome from the forehead and the hand. With data from the microbiome on the skin, the team could predict participants’ ages to within 4 years, versus 4.5 years for the oral microbiome and 11.5 for the gut microbiome.
Age-related changes in the skin biome are thought to reflect how human physiology changes over time. As humans get older, our skin becomes drier and produces less of the natural moisturizer sebum. The team’s findings could lead to noninvasive patient monitoring, says Xu, who is now at Nanchang University. He hopes that one day a simple microbiome test could be used to check how the elderly are aging or the condition of people with chronic diseases.