Children who suck their thumbs or bite their nails are less likely than others to have allergies later in life, according to a new study. Lending support to the “hygiene hypothesis,” which holds that early life exposure to microbes may decrease the risk of developing allergies, the study may explain why kids with oral habits have fewer allergies as adults, the authors write. However, researchers were clear that the results do not suggest that kids should take up these habits.
Many parents worry about the dental effects of thumb sucking in particular, and we don’t wish to dismiss these concerns, but if a child has a habit that is difficult to break, maybe there is some consolation in the fact that there may be a reduction in the risk of allergies.
Senior author Robert J. Hancox, MD, of the Dunedin School of Medicine at the University of Otago in Dunedin, New Zealand.
The study followed more than 1,000 children whose parents reported their nail biting and thumb-sucking tendencies at ages 5, 7, 9 and 11. The same kids were tested for allergies with pin-prick tests at ages 13 and 32. Researchers that found 49 percent of 13-year-olds who did not suck their thumb or bite their nails tested positive to at least one allergy, compared to 38 percent who practiced one of the habits. The allergy level fell to 31 percent for children who did both. The results remained the same when participants were 32-years-old, regardless of factors such as parental history of allergies, pet ownership or being breast fed. However, researchers cautioned that the findings need to be supported by more studies in different geographical regions around the globe.