Thumb-sucking builds immunity and leads to a reduced chance of developing allergies,McMaster University study reveals.
A new study has found that children who ever used to suck their thumbs and bite their nails are less likely to develop allergies later in life.
According to the study in August, the issue of Pediatrics,Dr. Malcolm Sears who is a respirologist at McMaster University in Hamilton and lead author of the longitudinal study said, “Our findings are consistent with the hygiene theory that early exposure to dirt or germs reduces the risk of developing allergies”, he also tracked a cohort of children from infancy to adulthood, for more than three decades.
“While we don’t recommend that these habits should be encouraged, there does appear to be a positive side.”
The outcome of the study as suggesting the oral bacteria influence immune response, support recent research that showed children whose mothers sucked clean their pacifiers were less likely to develop allergies.
Data of more than 1,000 participants who submitted to skin testing at ages 13 and 32 was analyzed by Sears and colleagues in New Zealand. In the test, dust mites, grass, mould, wool, dogs, cats, and horses were included as common allergens.
To the researcher, children between the ages of 5 and 11 were usually reported by parents as thumb-sucking and nail-biting habits. Among them, thirty-one (31%) per cent were frequent thumb-suckers or nail-biters. Fourty-five per cent (45%) of all the kids who were tested at the age of 13showed sensitivity to one or more of the allergens. Fourty per cent (40%) of these children had allergies either by sucking a thumb or biting their fingernails. While thirty-one per cent (31%) of these children had allergies Children with both oral habits fared better.
Summarizing: Age 5-11;
- Thumb-suckers or nail-biters : 31%
- Allergies either by sucking a thumb or biting fingernails: 40%
- Having allergies with both oral habits fared better: 31%
Household smoking, ownership of cats and dogs and exposure to house dust mites were ignored as contributing factors. Other variables that could be held responsible for the statistically significant differences, including breastfeeding, socioeconomic status and parents with allergies were also explored by researchers.
As per the study, no association between thumb-sucking and nail-biting with asthma or hay fever has found.
Back into history, in 1989,the idea that dirt and germs are good was developed by an epidemiologist, D.P. Strachan at the London School of Hygiene and Tropical Medicine.
Children from larger families seemed to benefit from “unhygienic contact” with older siblings; that early exposure to infections boosted their immune responses were thoroughly explained by him.
Though, the theory has spread over the decades but remains controversial. Study notes of Sears in the hygiene hypothesis fail to explain the rise of allergies in “unhygienic” inner-city environments and evaluated how probiotics are found ineffective at preventing allergic diseases.