Children Who Suck Their Thumbs Have Fewer Allergies
Children who suck their thumbs or nails beyond the preschool years may be less likely to allergic reactions when they reach adolescence bite, the researchers said.
In addition, the study found that the protective effect seemed to last into adulthood.
But no one is suggesting that children be encouraged to adopt these habits, said lead researcher Dr. Robert Hancox from the University of Otago in Dunedin, New Zealand.
With thumb sucking, in particular, there is concern that it may alter the alignment of teeth when they leave.
“We do not want to dismiss these concerns,” Hancox said.
“But if a child has a hard habit to remove, maybe that could be a reduction in the risk of allergies could provide some comfort,” he added.
How could the fact chronically putting your fingers in the mouth affect the risk of allergies?
According Hancox, all relates to the “hygiene hypothesis”. The theory is that exposure to bacteria and other microbes in early life helps guide the immune system to a way of fighting infection, and away from a tendency to allergic reactions.
But the study can not prove that neither habits directly reduce the risk of children sensitized to allergens, recognized Hancox.
But he said, his team took into account a variety of things that influence the likelihood of sensitization, including whether they were breastfed, exposed to secondhand smoke, they lived with pets or had a family history of allergies.
It is “hard to imagine” what other factors explain the findings, Hancox said.
At least one expert agreed that the hygiene hypothesis could explain the study results.
Dr. Mika Hiramatsu a pediatrician who reviewed the study, said “it is other evidence that support the hygiene hypothesis.” Hiramatsu is spokeswoman for the American Academy of Pediatrics (American Academy of Pediatrics).
He pointed to a similar connection observed in previous studies: children in day care, living with pets, they live on farms or have older siblings tend to have a lower risk of allergies and asthma, suggesting that relatively full environments germs They offer some protection.
“I think this study adds weight to the idea that children do better when they are exposed to a variety of microbes,” Hiramatsu said. “Being in a ‘sterile’ environment really is not the best for us.”
That does not mean that parents should allow their children to “wallow in the earth,” according to Hiramatsu. But they can “relax” a little about cleanliness, he said.
The study findings are based on more than a thousand children in New Zealand who entered the study at birth. The majority were followed into adulthood.
According to reports from parents, 31 percent of children thumb sucking or nail “often” gnawed between 5 and 11 years old. Those children were a third less likely than their peers to have developed an allergic sensitization at age 13.
That meant it was less likely to obtain a positive result when the skin was exposed to allergy triggers, such as pollen and dust mites.
The same pattern was still apparent at age 32, the researchers found.
But it is not clear exactly what that meant for the daily lives of people, Hancox said. Skin tests showed if a person had an allergic response to a particular substance. That does not necessarily mean that the person suffers symptoms daily.
The researchers did asked whether study participants had been diagnosed with asthma or hay fever. And there was a link between thumb sucking or nail biting and the risk of these conditions.
Hancox and his colleagues reported the findings in the online edition July 11 issue of Pediatrics.