People should pick their noses and eat the bogies to boost their immune system, according to an expert.
Dr Meg Lemon, a dermatologist in Denver, says she also tells people to eat food they drop on the floor.
Exposing the body to a range of germs could help to boost its natural defences and make people more resilient to infections and allergies, research has suggested.
And as society becomes cleaner and more antiseptic, it may be down to people to take matters into their own hands.
‘I tell people, when they drop food on the floor, please pick it up and eat it,’ Dr Meg Lemon tells science author Matt Richtel in his new book ‘An Elegant Defense: The Extraordinary New Science of the Immune System’.
In an excerpt published in the New York Times, for which Mr Richtel is a journalist, Dr Lemon said: ‘Get rid of the antibacterial soap. Immunize!
‘If a new vaccine comes out, run and get it. I immunized the living hell out of my children. And it’s O.K. if they eat dirt.’
‘You should not only pick your nose, you should eat it,’ she added.
Based in Denver, Colorado, Dr Lemon is a dermatologist certified by the American Board of Dermatology.
Her advice supports the theme of the excerpt of Mr Richtel’s book, which suggests modern immune systems are becoming overly sensitive to once-harmless germs.
He points to research which has in the past shown children are more likely to develop allergies such as hay fever if they have fewer siblings.
The reasoning, according to a study in the British Medical Journal in 1989, is that catching infections from older siblings bolstered young children’s immunity.
Those who didn’t have older brothers and sisters bringing home bacteria and viruses they picked up outside had sheltered, less battle-hardened immune systems.
And those were the ones who developed allergies.
Over time, families have become smaller as people have fewer children and Western societies are increasingly focused on keeping their homes, bodies, food, water and milk clean and sterilised.
At the same time, the prevalence of allergies has risen.
He also warns that overprescribing antibiotics may have contributed to the effect because they can destroy healthy bacteria if given when they’re not needed.
Overuse of antibiotics also allows bacteria to mutate to become more deadly and more difficult to treat.
An article published in The British Journal of Homeopathy more than a century ago said hay fever was ‘almost wholly confined’ to the upper classes, who had better hygiene, suggesting poor children who were exposed to more germs had low rates of hay fever because of their bolstered immune system.
Mr Richtel admits many advances in hygiene have been useful for society and improved the health and lives of modern people.
But he suggests the immune system could still benefit from training to make it better at fighting infection – and picking your nose or eating dirty food could be a way to do that.
‘Our immune system needs a job,’ Dr Lemon added.
‘We evolved over millions of years to have our immune systems under constant assault. Now they don’t have anything to do.’
‘An Elegant Defense: The Extraordinary New Science of the Immune System’ by Matt Richtel is published by William Morrow.