Kids Who Bite Their Nails And Suck Their Thumbs Have Fewer Allergies, Says Research

Getting down and dirty.

Parents are constantly telling their children to get dirty, bacteria-laden things out of their mouths, like the remote control, a sucker they found on the ground, and especially their hands. 

But while thumb sucking and nail biting are generally regarded as bad habits, scientists have found that kids who do those things have fewer allergies than those who don't. 

A team of researchers from New Zealand has been following 1,000-plus people from childhood into adulthood in order to learn about how these oral habits played into the development of allergies. Researchers discovered thumb sucking or nail biting habits through periodic surveys about lifestyle habits during childhood, then compared those results with allergy tests given at ages 13 and 32.

The results, which were published in Pediatrics, found that those who either sucked their thumbs or bit their nails as a child had about a 40 percent chance of having allergies. That number dropped to 35 percent for those that did both of those things as children. As a comparison, the kids who didn't routinely have their hands in their mouths were 45 percent likely to develop allergies.


The results of the study make sense, as there has been a growing body of evidence that kids who are exposed to dirt, germs, and allergens early are less likely to develop allergies because their immune systems are being trained to handle those things. 

This could apply to a kid in the country who spends a lot of time outside in the dirt and around animals, but kids in the city are also exposed to allergens carried by mice, insects, or through pollution. 

What the current study did not find, though, was any connection between kids who kept their fingers in their mouths and a decreased risk of developing asthma or hay fever. 

While there is a positive side to kids being exposed to these allergens through nail biting and thumb sucking, that doesn't necessarily mean children should be allowed to put whatever they want in their mouths with no regard to what microbes might be lurking on them. Plus, there is also the risk that a child who sucks their thumb for too long will develop oral problems when their adult teeth start to come in.

Everything in moderation!

Cover image: Shutterstock


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