Can thumb-sucking prevent future allergies?

Children who sucked their thumbs or bit their nails were associated with a statistically significant reduced risk of developing allergies as adults, according to another study that appeared to support the "hygiene hypothesis."

Young children with at least one "oral habit" (thumb-sucking, nail-biting or both) were associated with a 39% reduced risk of developing atopic sensitization, or common allergies at age 32, reported Stephanie J. Lynch, of University of Otago in Dunedin, New Zealand, and colleagues.

However, there was no significant association between children with at least one oral habit and the likelihood of developing allergies at age 13, the authors wrote in Pediatrics.

Explaining the hygiene hypothesis, Jay Portnoy, MD, of Children's Mercy said "Children with such habits are known to ingest bacteria that are on their hands and this is believed to protect them from developing allergies later in life."

"It is possible that other factors may have played a role, but the investigators controlled for as many factors as they could think of and this did not change the results," Portnoy, who was not involved with the study, told MedPage Today via email.

The association between oral habits and reduced risk of allergies appeared to be most pronounced later in life. Even after adjusting for confounders, the relationship between thumb-sucking and nail-biting and a decreased risk of allergies remained significant.

Portnoy also seemed to feel that the topic needed more research, adding "Of course further studies may provide more detailed information about this, so stay tuned."

Read the full story via MedPage Today.

Learn more about the Division of Allergy, Asthma & Immunology at Children's Mercy.