When it comes to thumb-sucking, not much is good news. Sure, it looks cute to see a baby with a tiny thumb in its mouth, but the act has been known to lead to an increase in stomach bugs — thanks to the ingesting and spreading of germs from fingers — and even push the front teeth forward, resulting in thousands of dollars spent on orthodontia.
But today, there's actually reason to celebrate thumb-sucking, along with the equally nefarious childhood habit of nail-biting.
According to a longitudinal study published in the journal Pediatrics, children who suck their thumbs or bite their nails may have a lower risk of developing allergies.
"The findings support the 'hygiene hypothesis,' the idea that reduced exposure to microbial organisms, in other words increased hygiene, is responsible for the rise in allergic diseases seen over recent decades," said Bob Hancox, the study's lead author. "[This study] suggests that being exposed to microbes as a child reduces your risk of developing allergies."
In fact, children who sucked their thumbs or bit their nails were more than a fifth less likely to have allergies – to common things like dust, grass, animal dander, and molds – as adults. And if kids took part in both habits, the risk was cut by more than a third.
Still, the researchers out of New Zealand's University of Otago maintain that it's unclear if there is a true health benefit, and although skin testing showed fewer allergies among thumb-suckers and nail-biters, they found no difference in their risk for developing allergic diseases such as asthma or hay fever.
Bottom line: If your kid does either of these, rest easy. If they don't, this by no way means parents should start encouraging their kids to take up these habits.