Study: Thumb-Sucking May Be Good For Kids' Health

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MIAMI (CBSMiami) -- A new study suggests some unsanitary habits many kids have may not be so bad for their health.

Like lots of kids, Gracie Ingram used her hands to soothe herself as a baby.

"When I was little instead of sucking a pacifier, I sucked my fingers instead," said 9-year old Ingram.

Like lots of parents, her dad Chris couldn't seem to stop her.

"We felt like we ought to discourage it but she was pretty tenacious," said Chris.

Turns out Gracie may have been doing a good thing.

A new study published in the Journal of Pediatrics shows children who bite their nails and suck their thumbs are about one-third less likely to develop certain allergies.

"Cat, grass, house dust mite, and dog. Those were reduced, some significantly, some borderline," said Prof. Malcolm Sears of McMaster University School of Medicine.

Researchers say the findings may be another example of what's called the hygiene hypothesis - the idea that being too clean may increase a child's risk of allergies.

"Early exposure to dirt is not a bad thing," said Prof. Malcolm Sears with McMaster University School of Medicine. "When they suck their thumbs or bite their nails, they're exposing themselves to additional microbes or dirt which is stimulating the immune system."

‎Researchers said this isn't a recommendation for kids to take up nail-biting and thumb-sucking.

One mother suggests -  just let kids be kids.

"You should be out playing in the grass and playing in the dirt… right? That's what kids should do," said mother Salima Milliot.

The study looked at more than one thousand children from New Zealand from age 5 and followed them into their 30s.

While researchers found decreases in the risk for certain allergies, they didn't find an association with hay fever or asthma.