Could kids’ thumb-sucking, nail-biting offer benefits?


(CNN)Thumb-sucking and nail-biting can cause health problems for kids and potential financial problems for parents paying for braces. Thumb-sucking can interfere with the alignment of children’s teeth and nail-biting can increase the risk of spreading harmful germs from their fingers to their mouths.

Those two childhood habits, however, come with a surprising upside, according to a study published in the journal Pediatrics on Monday.
    Children who suck their thumbs or bite their nails may have a lower risk of developing allergies, said Bob Hancox, a co-author of the study and an associate professor at the University of Otago’s Dunedin School of Medicine in New Zealand.
    “The study was done to test the hygiene hypothesis: the idea that reduced exposure to microbial organisms, in other words increased hygiene, is responsible for the rise in allergic diseases seen over recent decades,” Hancox said. The hypothesis also has been described as including the use of antibiotics.
    When the children were 5, 7, 9 and 11, their parents were asked to complete questionnaires about their children’s thumb-sucking and nail-biting habits. About 31% of the children were frequent thumb-suckers or nail-biters.
    Then, when the children were 13 years old, the researchers administered a skin-prick test to determine whether they had allergies. Another skin-prick test was repeated when the participants were 32.
    It turned out that children who were thumb-suckers, nail-biters or both had a 30% to 40% risk reduction in their chances of having allergies in childhood, which persisted in adulthood. No associations were found for nail-biting or thumb-sucking and asthma or hay fever.
    In theory, the findings suggest that thumb-sucking and nail-biting may lead to a more diverse variety of environmental bacteria and other microbes entering the body, possibly boosting defense against developing allergies. However, that was not really tested.

    See the latest news and share your comments with CNN Health on Facebook and Twitter.

    “How exactly exposure to microbes alters immune function in this way is not known,” Hancox said. “But it is suggested that increasing microbial exposure influences the immune system to fighting infections rather than developing allergies.”
    What do other experts think of the research?
    The data would be much stronger if they showed a consistent strong correlation between thumb-sucking or nail-biting and allergies as well as asthma, after controlling for other known factors which affect these diseases, noted Dr. Purna Kashyap, a gastroenterologist at the Mayo Clinic who was not involved in the study.
    “Overall, it is interesting but needs better data to support the conclusion,” he said.

    Read more:


    Please enter your comment!
    Please enter your name here