Children who suck their thumb or chew their nails are less likely to develop allergies later in life, researchers from the Dunedin Study have found.
The Dunedin Study – featured in documentary series Why am I? – has been following a cohort of 1037 participants since they were born in 1972-73. Their latest results, published in Pediatrics, have found a link between thumb-sucking and nail-biting and a lower risk of developing allergies.
Lead researcher Professor Bob Hancox said childhood exposure to microbial organisms through thumb-sucking and nail-biting might alter immune function so that those children were less prone to developing allergies.
Children in the longitudinal study were assessed for thumb-sucking and nail-biting habits at ages 5, 7, 9, and 11 years then checked at ages 13 and 32 for atopic sensitisation – a positive skin prick test to at least one common allergy.
Children who sucked their thumbs or bit their nails had a lower prevalence of sensitisation, compared to children who did not. Professor Hancox said the effect persisted into adulthood, which supported the ‘hygeine hypothesis’ – the suggestion that early exposure to microbes reduces the risk of later developing allergies.
Read more about the research on scimex.org.
The findings were widely covered in New Zealand media:
NZ Herald: Thumb suckers have fewer allergies later in life
Otago Daily Times: Thumb-suckers, nail-biters show fewer allergies
Stuff.co.nz: Thumb-suckers could have less allergies, study shows
Newshub: Bite nails, ward off allergies – study
TVNZ: Thumb-suckers rejoice! Shoving fingers in your mouth could be good for you
Radio NZ: Thumb-sucking may prevent allergies in later life – study
The New Zealand-led research was also widely reported in international media, including:
Scientific American: Thumb-Sucking, Nail-Biting Kids May Have Lower Allergy Risk
BBC News: Thumb-suckers and nail-biters have ‘fewer allergies’
Forbes: Scientists Discover One Surprising Possible Benefit Of Thumb-Sucking And Nail-Biting
The Washington Post: Thumb-sucking and nail-biting might prevent allergies