If you’re wondering how long you’ll live, the answer could be right at your fingertips.

According to Dr David Sinclair, a professor of genetics at Harvard Medical School, your nails are actually a clear sign of your biological age.

And unfortunately, getting more frequent manicures won’t offer any improvements.

“The rate of your nail growth is a really good indicator of how you’re aging or not aging,” Dr Sinclair recently said on his podcast Lifespan. 

“Every time I have to cut my nails, I’m thinking, ‘How long ago did I cut my nails?’” he added. 

Sinclair cited a 1979 study in which researchers attached tiny measuring tapes to 271 individuals and monitored their nail growth over several years. 

They found that the rate of fingernail growth decreases by approximately 0.5 per cent per year starting at the age of 30. 

This suggests that the rate of nail growth could serve as a simple, noninvasive indicator of biological aging – defined as how “old” the body is based on the efficacy of your cells and tissues, as opposed to your chronological age, which denotes how many years you’ve been alive. 

If you find yourself needing to cut your nails more often than your peers, that could be a sign that you’re faring well in the biological age department. 

It is natural for nails to grow slower and become more brittle or yellowish in colour as you get older.  However, in some cases, changes in your nails could be a sign of an underlying health issue. 

For example, white or pale nails could signal anemia, liver disease, heart failure or malnutrition.

Yellow nails could indicate fungal infections, diabetes or thyroid disease. 

While vertical ridges are a common sign of aging, ridged nails could also be caused by nutritional deficiencies or autoimmune diseases like rheumatoid arthritis.

And clubbing – a condition in which the nails become curved and thick – might point to lung disease, inflammatory bowel disease, cardiovascular disease or liver issues.

Nail growth rate may indicate aging, but if your nails are weak and break more often, there could be other causes at play.

Dr Mary Stevenson, a dermatologic surgeon at NYU Langone, said a lot of factors can lead to brittle, easy-to-chip nails. One is not getting enough protein in your diet, which will lead to less keratin, the protein that makes up our nails. Nutritional deficiencies in vitamin B and iron can hurt, too.

Handwashing, using abrasive cleaning materials like dish soap and detergents and having trauma to the nail bed can also weaken nails. She also warned against cutting cuticles during a manicure.

“We need our cuticles. Pushing these back and removing them separate the seal they make with our nail to keep things like bacteria and fungi out,” she said.

“Letting your nails ‘breathe’ or have time free from manicures is not essential to healthy nails, though too much acetone or abrasive manicures that can be removed with thinning the nails and acetone soaks, or improper manicures can weaken our nail.”

She recommended biotin and iron to strengthen and lengthen nails, but noted that it takes months of supplementation to see a difference.