Why you should let your children eat dirt

Should we be saving our kids from an over sanitised world?
Should we be saving our kids from an oversanitised world?

Alfie, my second son, loves nothing more than grubbing around in the dirt. He spends hours in the garden, with his toy excavator, moving earth out of the beds and digging up plants, much to the intense irritation of his father.

We have a London garden, which I’m guessing has every bit as much bacteria per square metre as a garden in the country.

It’s a latrine for local cats, pigeons and squirrels. When we got back from holidays, a particularly skilled fox had managed to leave a poo on our football.

Alfie, outdoors
Alfie, pulling his truck

All this makes me wonder if I should even be letting my children outside. I always make Alfie wash his hands when he comes inside but you should see the colour of the bath water.

A new book, Let Them Eat Dirt, has completely put my mind at rest, however.

Written by two microbiologists, B.Brett Finlay and Marie-Claire Arrieta, it sets out to educate parents about the potential health hazards of raising children in an oversanitised home.

Our war against dirt and more specifically microbes, those tiny organisms such as bacteria, viruses and protozoa that can only be seen in a microscope, has worked well, too well.

We’ve developed antibiotics, antivirals, vaccinations, chlorination, pasteurisation and sterilization to combat these microbes and, in many respects, we’ve beaten them. In 1915 the average life span in the US was 52 years, now people often live well into their eighties.

But while some microbes can be very dangerous, many are harmless and we depend on them to live. They’re responsible for digesting most of our food and they supply essential vitamins such as vitamin K, which ensures our blood coagulates.

Alfie, boots on, ready to start digging
Alfie, boots on, ready to start digging

According to the authors of this book, our zero tolerance approach towards microbes has led to an explosion in non-infectious diseases and disorders in developed countries.

The book suggests that a lack of exposure to bacteria and parasites, specifically in childhood, is to blame for the rise in diabetes, asthma, allergies, inflammatory bowel diseases, autism, certain types of cancer and obesity.

By tampering too much with the natural balance, we are putting our children in danger.

It was Professor David Strachan, an epidemiologist from London, who first came up with this theory about 25 years ago.

He believed that missing out on exposure to microbes can lead to the immune system reacting fiercely to harmless microbes, which can trigger inflammatory responses in various organs.

Grubbing with grandpa
Grubbing with grandpa

The book explains how parents can introduce microbes into their children’s lives in a safe way from pregnancy through childhood.

There are chapters helping parents to navigate a world in which formula, antibiotics, sterilization, and a sugar-rich diet are the norm, from the point of view of microbiota.

There’s even a chapter on the microbiotic benefits of household pets: Finlay and Arrieta have a lot of time for dogs.

If you’re not sold on it yet, perhaps the chapter on microbiota and the brain will put the fear into you. Apparently the brains of germ-free mice don’t develop normally…

The book has made me feel altogether better about my children’s grubby habits.

It’s refreshingly unpreachy, whilst making a good case for an altogether dirtier existence without reliance on antibiotics or antibacterial hand gel.

Although even Dr Finlay and Dr Arrieta do insist that we must always wash our hands before we eat.


  • Let Them Eat Dirt: Saving Your Child From An Oversanitised World by B.Brett Finlay and Marie-Claire Arrieta is available on Amazon




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