Nail growth and aging

In this Article (Index)

• Nail Growth and Aging
• Nail Trivia and Curious Facts

Association between nail growth rate and aging

In a 2022 podcast (1) Dr. David Sinclair, a genetics professor at the Harvard Medical School stated that "the rate of your nail growth is a really good indicator of how you're aging or not aging." He mentioned a 1979 paper (2) that reported that fingernail growth slowed down by approximately 1/2% per year after the age of 30.

Adding that faster nail growth shows that you are aging at a slower rate than average. Sinclair implied that nail growth is a key indicator of how efficiently the body regenerates healthy cells and reflects how it is coping with aging.

The 1979 study (2) reported that measuring nail growth was a "simple, inexpensive, noninvasive technique for the measurement of aging." Growth rate was linked to age and caused by age. The study found that nail growth fell by 50% throughout the lifespan of human beings, and also dogs.

In Beagles, dogs who live 5 times less than a human, the nail growth rate decreases 5 times faster than that of a human being.

In the case of humans, the paper noted that nail growth in humans increases well into the thirties. Then it drops at a rate of 0.5% per year from a peak of 0.9 mm (millimeters) per week at the age of 25, equivalent to 3.92 mm/ month = 1.54 inches/ month.
Men have faster growth than women into their 60s. By that age, growth was 0.65 mm/ week, but from then onwards women's nails grew faster than men's (0.65 vs 0.55 mm/ week by the 80s).

The nail growth speed has remained constant since 1979, as shown by a paper published in 2010 (31 years later) (3) which measured the growth of fingernails and toenails by physically measuring the length grown by marking the nails of 22 healthy young adults.

This study found that fingernails grow faster than toenails (3.47 mm vs 1.62 mm/ month). Left and right nails grew at a similar pace, but the little fingernail grew fastest and the great toenail (of the big toe or hallux) grew faster than the other toenails.

It confirmed that younger people and men had a faster growth rate, as did those who bite their nails (onychophagia).

Nail Trivia and Curious Facts

The nails of men and women have a different composition, as shown by a 2017 study. (4) Regarding amino acids, it found that men have more Leucine and Alanine, and less Arginine and Isoleucine than women. The α-keratin protein in men has more disulfide bonds, β-sheet bonds, and random coil secondary structures, it has fewer α-helical regions. The disulfide bonds make men's nails stiffer than those of women.

The nail growth rate is slower in immuno-compromised people, those who are immobilized or paralyzed, have deficient nourishment, suffer from acute infection, or undergoing anti-mitotic drug therapy (5)

Nail growth in high altitude settings according to a 2017 study in Ladakhi, India at 3,445 m (11,302 ft) suggests that the lower oxygen levels and partial pressure lead to "a significant decrease in the nail growth in high altitude as compared to the rate of nail growth seen in plains." (6)

Different studies have found that there are no marked seasonal changes in nail growth rate, the height and weight of a person do not affect the growth rate. Children younger than 14 have a faster growth rate than young adults.
Nails may grow faster during pregnancy.
No, nails do not grow after someone dies, it seems that they do because the skin retracts as it loses hydration making the nails seem longer.

Cold weather seems to affect nail growth, slowing it down as reported by a 1958 study, however, studies conducted in the Antarctic in 1977 and 1983 didn't notice any retarding effect, perhaps reflecting better insulation and warmer gear used after the 1970s by those based in the polar regions compared to the 1950s. (7)