Thumb Sucking And Nail-Biting In Children Can Lower The Risk Of Developing Allergies, Experts Suggest

Parents have always known that thumb sucking and nail biting are habits that are so hard to break. However, a recent study found that it's not really all that bad. Researchers found these habits, thumb sucking and nail biting in young children, may be a way to protect them against allergies.

Today.com said that a report published in Pediatrics, children who sucked their thumbs and bit their nails were found to have lesser chances of developing sensitivities to common allergies compared to those children without any of the habits.

However, that doesn't mean that parents should encourage children to start sucking on their thumbs if they aren't doing it, says study coauthor Dr. Bob Hancox, an associate professor of preventive and social medicine at the Dunedin School of Medicine in New Zealand.

A safer strategy might be "having pets-cats and dogs-which also appear to protect against [allergies]," Hancox says. "Whether this is regarded as a positive behavior depends on family circumstances."

The study, led by the University of Otago in New Zealand, followed the progress of 1,037 participants from birth through to adulthood. According to The Telegraph, parents reported their children's thumb-sucking and nail-biting habits at age 5, 7, 9, and 11. These children were then tested for allergies using skin prick test. Researchers tested at least one common allergen at ages 13 and 32.

Findings revealed that 38 percent of children who had the habit had lower prevalence of sensitization at 13 than those who did not have the habit at 49 percent. However, those who were doing both sucking their thumb and biting their nails had an even lower risk with 31 percent. The link between allergen sensitivity and thumb sucking and nail biting was still seen at age 32.

The New York Times reported that researchers had a hard time explaining other factors related to allergic risk. Pets, parents with allergies, breast-feeding, socioeconomic status and few other things were made as controls for the study. And although children with thumb-sucking and nail-biting habits showed lower allergic sensitization, their risk for developing asthma and hay fever were the same.

Dr. Hancox explained in an email that the hygiene hypothesis can play a part in this study. "It suggests that lifestyle factors may be responsible for the rise in allergic diseases in recent decades. Obviously hygiene has very many benefits, but perhaps this is a downside. The hygiene hypothesis is still unproven and controversial, but this is another piece of evidence that it could be true."

Meanwhile, Dr. Alison Morris, a professor of medicine in the division of pulmonary, allergy and critical care at the University of Pittsburgh and director of the university's Center for Medicine and the Microbiome found the results intriguing. "If parents can't get their kids to stop sucking their thumbs, this may make them feel better about that," Morris says. "But I don't think the study offers anything actionable at this point other than to be more relaxed about children's exposures to germs."