A dermatologist is claiming an easy trick to boost your immune system is to pick your bogies - and eat them.

Dr Meg Lemon, from Denver, Colorado, is also advising people to eat their food after it's been dropped on the floor, and promotes the idea that we shouldn't be so afraid of germs, reports the Daily Mail.

Dr Lemon says you shouldn't be telling your child to take their finger out of their nose at all.

Featured in a new book "An Elegant Defense: The Extraordinary New Science of the Immune System", by science writer Matt Richtel, Dr Lemon tells the author "You should not only pick your nose, you should eat it."

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And she says when people drop food on the floor, she tells them "please pick it up and eat it."

An extract from the book was published in the New York Times, where Richtel works as a journalist. In it Dr Lemon advises: "Get rid of the antibacterial soap. Immunise!

"If a new vaccine comes out, run and get it. I immunised the living hell out of my children. And it's O.K. If they eat dirt."

READ MORE: Mum bans anti-vax friend from seeing child

Meanwhile, Richtel believes people are becoming more susceptible to disease because of the cleaner, more antiseptic world we now live in.

He refers to research which proves children with fewer siblings have a higher chance of developing allergies.

A study in The 1989 British Medical Journal revealed the reason for this is because catching a virus from an older child assists in boosting the younger child's immunity.

It found that the children who developed allergies were those who didn't have others bringing germs into the house, which meant their immune system was more sheltered.

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Research shows the prevalence of allergies has risen as Western societies have focused more on creating super clean environments and people tend to have fewer children.

Auckland DHB's Clinical Immunology and Allergy service shares on their website the diagnoses of food allergies has increased in the last two decades: Before the 1980s allergy was comparatively rare. Now around 15 per cent of the population report an allergy to a type of food.

The International Study on Asthma and Allergies in Childhood found the prevalence of asthma and allergies was highest in developed countries such as New Zealand.

Richtel points to findings that show in 2011, 50 per cent more children in the US had developed food allergies than the number recorded in 1997.

During this time skin allergies skyrocketed by 69 per cent.

He points to doctors prescribing antibiotics too commonly as potentially playing a part in this, due to the medication breaking down good bacteria if it's taken unnecessarily.

In fact, says Richtel, the over-prescription of antibiotics gives bacteria the ability to become more perilous and harder to treat.

The British Journal of Homeopathy published an article over 100 years ago claiming fever was "almost wholly confined" to higher class people who had better access to staying clean and less exposure to germs.

The British Journal of Homeopathy said over a century ago that hay fever was more common amongst the upper classes. Photo / Getty Images
The British Journal of Homeopathy said over a century ago that hay fever was more common amongst the upper classes. Photo / Getty Images

Richtel acknowledges hygienic advances have been beneficial for the world, but emphasises immune systems will benefit if they're more exposed to germs.

"Our immune system needs a job," Dr Lemon said.

"We evolved over millions of years to have our immune systems under constant assault. Now they don't have anything to do."