If someone ever gives you flak for biting your nails or sucking your thumb again, justify your habit by saying you’re simply looking after your allergies.
According to a team of researchers, who published their findings in the journal Pediatrics, these notoriously-bad habits appear to prevent allergies in the sample group they tested.
They call it the ‘hygiene hypothesis’: exposing the body to some germs strengthens the entire body’s immune system collectively. The University of Otago, Dunedin, team believes this could be why allergies appeared preventable amongst the 1,000 people in New Zealand they assessed.
The two habits were examined and recorded at ages five, seven, nine and 11, and allergies were tested for at age 13 and 32. Roughly a third of the group were active thumb-suckers or nail-biters, and it was that third that were much less likely to have allergies by age 13. The odds of developing an allergy to things like dust mites or pets was also a third lower for the group.
The protective cocoon from nail-biting and thumb-sucking appears to persist into adulthood, say the researchers, though this claim is less black and white. The way the study was designed impedes the team from determining whether these links are merely casual.
“While we don’t recommend that these habits should be encouraged, there does appear to be a positive side to these habits,” said co-researcher Prof Malcolm Sears, from McMaster University, Canada.
“Research that has been carried out in other countries also adds weight to this theory of the role the environment and gut microbiota play in shaping an individual’s potential to develop a food allergy,” adds Holly Shaw, of Allergy UK.
“Having pets at home, older siblings and living on a farm have also been identified as environmental influences that may have a role in the development of allergic disease.”