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17th Jul 2016

It’s disgusting, but biting your nails might actually be good for you

Here's the science behind it...

Declan Cashin

Parents, partners and friends have probably tried to smack the bad habit out of you, and you might have tried those smelly potions on your cuticles as aversion therapy.

But what if the nasty habit of biting your nails is actually good for you?

According to a new study, people who bit their nails and sucked their thumbs as children may have fewer allergies and sensitivities as adults.

tom hanks

Via 20th Century Fox

Furthermore, if kids have both habits, they are less likely to be allergic to things like “house dust mites, grass, cats, dogs, horses or airborne fungi”.

The study, completed by researchers at New Zealand’s Dunedin School of Medicine, focused on a group of 1,000 children, monitoring their nail-biting and thumb-sucking habits at ages 5, 7, 9 and 11.

“Our findings are consistent with the hygiene theory that early exposure to dirt or germs reduces the risk of developing allergies,” said Professor Malcolm Sears of McMaster University’s Michael G. DeGroote School of Medicine..

“While we don’t recommend that these habits should be encouraged, there does appear to be a positive side to these habits.”


Via Hat-Trick Productions/Channel 4

The scientists aimed to test the notion that thumb-sucking and nail-biting would increase microbial exposures, and minimise the development of allergic reactions known as “atopic sensitisation’.

This was then measured by a skin-prick test when the children under observation were 13 and 32 years old.

Some 31 per cent of children were frequent thumb suckers or nail biters, and among all children at 13 years old, 45 per cent showed atopic sensitisation.


However, among those with one of the habits, only 40 per cent had allergies. Furthermore, of those with both habits, only 31 per cent had allergies.

“This result was sustained into adulthood, and showed no difference depending on smoking in the household, ownership of cats or dogs; or exposure to house dust mites,” the team noted in a press release.

That being said, it seems we should still be cautious about nail-biting and thumb-sucking. As one doctor told Refinery29: “Bacteria often gets stuck under the nails, and can then be transferred to the mouth, causing infections of the gums and throat.” Snapchat