Children who suck their thumbs or bite their nails are less likely to develop allergies, a study says. Published in the journal Pediatrics, the study suggests that this could be due to and further proof of the “hygiene hypothesis” for allergy development.
The study looked at 1,000 children assessed periodically in New Zealand between the ages of 5 and 32. The thumb sucking and nail biting habits of the children were assessed at ages 5, 7, 9, and 11 with allergy tests coming at ages 13 and 32.
Children who bit their nails or sucked their thumbs in childhood were significantly less likely to have allergies at age 13.
The odds were about 33 percent lower, in fact, for common allergies such as pet or dust mite. The researchers admit, however, that their study design does not allow them to say that the thumb sucking or nail biting habits were causing lower allergies or merely a part of a broader range of habits that could help lower risks. The likely scenario is the latter, but the study could be further proof that the hygiene hypothesis for allergy development has merit.
The hygiene hypothesis assumes that exposure or lack thereof is a prime motivator for development of allergies in children. The “cleaner” the environment of the children in question, the higher their risk of developing allergies to dust, pollen, foods, etc.
This study’s findings coincide with other studies that have shown that living on a farm, having older siblings, and having pets in the home are also attributed to lower allergy risk.