An interesting new study out of New Zealand suggests that young children who suck their thumbs or bite their nails may be at a lower risk for developing allergies.
The study included data from 1000 children born in New Zealand in 1972 or 1973, and spanned three decades.
While the results of the study suggests these habits may lower children’s risks of developing allergies, researchers noted that they are not recommending that kids take up these habits, only that the habits may play a role protecting them against allergies into adulthood.
"Many parents discourage these habits, and we do not have enough evidence to [advise they] change this," said Dr. Robert Hancox, an associate professor of respiratory epidemiology at the University of Otago in New Zealand. "We certainly don't recommend encouraging nail-biting or thumb-sucking, but perhaps if a child has one of these habits and [it] is difficult [for them] to stop, there is some consolation in the knowledge that it might reduce their risk of allergies.”
The researchers asked the parents of the children participating in the study about their kids’ thumb-sucking habits and nail-biting habits four times: when the kids were 5, 7, 9 and 11 years old. Researchers also tested the children for allergies using a skin-prick test when they were 13, and then followed up with the kids again when they were 32.
It turned out that 38 percent of the children who had sucked their thumbs or bit their nails had at least one allergy, whereas among kids who did not have these habits, 49 percent had at least one allergy.
Moreover, the link between these childhood habits and a lower risk of allergies was still present among the study participants when they were 32 years old. The link persisted even when the researchers took into account potentially confounding factors that may also affect a person's risk of allergies, such as whether their parents had allergies, whether they owned pets, whether they were breast-fed as infants and whether their parents smoked.
By the time the children were 13 years old, researchers found that the ones who both sucked their thumbs and bit their nails were even less likely to have allergies compared with children who had just one of the two habits. However, by the time they were 32, this association was no longer found.
The study was published in the July edition of the journal Pediatrics.
The results of this study are inline with another study published in 2013, which found that children whose mothers sucked their kids’ pacifiers clean had a lower risk of developing allergies.
"Although the mechanism and age of exposure [to pathogens] are different, both studies suggest that the immune response and risk of allergies may be influenced by exposure to oral bacteria or other microbes," the researchers wrote in the new study.
The new findings also lend support the so-called hygiene hypothesis, which holds that environments that have too little dirt and germs may make children more susceptible to certain conditions, including allergies. It seems that "exposure to microbial organisms influences our immune system and makes us less likely to develop allergies," Hancox told Live Science.
Kids that suck their thumbs or bite their nails, receive mixed reactions from adults. Most adults will encourage kids to stop biting their nails, while it’s probably 50/50 on the thumb sucking. Either way, it appears that oral bacteria may play a role in lowering the risks of developing allergies in kids.
Story source: Agata Blaszczak-Boxe, http://www.livescience.com/55340-children-thumb-sucking-nail-biting-allergy-risk.html