Proud to be a Thumb Sucker and Nail biter in childhood

Nail biting and thumb sucking are the common oral habits of most of the children. But most parents try to stop the child from these kind of habits. The thumb sucking and nail biting habits between the age of 3 and 7 would minimize the risk of allergies such as asthma, atopic sensitization and hay fever during the age of 14. Atopic sensitization is the syndrome which is the predisposition to the allergic hypersensitivity. Research proved that, those oral habits would minimize the Atopy.

During nail biting and thumb sucking, they increase association of microorganisms such as Escherichia coli, and other parasite intestinal infections. It seems, the nail biting introduce wide variety of microbes to the gut microbiome. The immune stimulation secondary to the exchange of maternal oral bacteria might protect against allergies.

If the hygiene hypothesis is correct, then the nail biting and thumb sucking would reduce the risk of allergies. Hygiene hypothesis stated that childhood exposure to the microbial organisms reduce the risk of developing allergic diseases. Though the effect of thumb sucking and nail biting habits are likely to increase the microbial exposure, their direct effect on allergies are still unknown.

Reference: 
Stephanie J. Lynch, Malcolm R. Sears, Robert J. Hancox, (2016), "Thumb-Sucking, Nail-Biting, and Atopic Sensitization, Asthma, and Hay Fever", Pediatrics.