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You might already know that your fingernails can reveal a surprising amount about your health status, showing signs of everything from anaemia to, in some rare cases, a form of melanoma.
But according to Dr David Sinclair, a Harvard-based expert in ageing and genetics who’s known for his research into longevity, they can tell us how we’re ageing too.
In 2022, the doctor explained on a podcast that one sign on our hands “is a really good indicator of how you’re ageing or not ageing.”
It’s based, he explains, on a 1979 study.
What’s the change?
Our nails do not grow as quickly when we’re older as they did in our younger years, the doctor explained.
“Every time I have to cut my nails, I’m thinking, ‘How long ago did I cut my nails?’”, he commented.
He pointed to a 1979 study in which researchers attached tape to people’s nails and measure how much they grew in different populations over a set period of time.
This paper, published in the Journal of Investigative Dermatology, found that, “The rate of linear nail growth decreases 50% over the life spans of both dogs and humans.”
As Dr Sinclair points out on the podcast, the study showed that the rate was about 0.5% each year after the participants’ 30th birthday.
A 2011 study put the start point even earlier, at 25 years of age.
While the professor admits that he doesn’t pay much attention to his own nail’s growth, he adds: “If you measure that, it’s a really good indicator of how old you are biologically.”
Why does that happen?
According to Healthline, it may have to do with blood flow, which slows over time.
Previously, Dr Michelle Henry, founder of Skin and Aesthetic Surgery of Manhattan, told HuffPost that, “As we age, our bodies start to produce less of the natural proteins found in nails, which can lead to nails becoming more brittle, dry, and prone to breaking.”
He added: “These keratin proteins are also found in our hair follicles, which is why we may also see a change in our hair texture as we age.”
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