Expert Editions vol. 20: Why dirt is good for children

dirt is good for children

It seems we have become a nation of clean freaks. Don’t touch this! My god – don’t put that in your mouth! Stay away from that – it’s dirty. I for one have been hugely guilty of this, until a book called Let Them Eat Dirt: Saving Your Child From An Oversanitized World  by Dr B Brett Finlay and Dr Marie-Claire Arrieta  landed on my doorstep and opened my eyes up to the mistakes I had been making.

The crux? Dirt is good for children and children need to be exposed to dirt and microbes for the sake of their immune seasons – not over zealously protected from them. And so now the big question: Could it be that in our mission to over sanitize the world we are unwittingly screwing up our children’s health? If you’re wondering whether this is true like me, read on for my interview with the authors of the book to find out in this issue of Expert Editions…

We seem to have become obsessed with cleanliness….why is this not necessarily a good thing for our kids?

Hygiene practices are good when used effectively to prevent the spread of the disease but our society has gone above and beyond that and kids are being cleaned just because. As we are learning now, microbes in our bodies are not just quiet residents; they perform essential tasks during our development, such as the development of our immune system and important aspects in our energy metabolism. They are crucial to our health and excessively cleaning our selves deprives us from this exposure.

Why is exposure to dirt and microbes actually very important for kids?

What is important for our kids is not necessarily just dirt but microbes in general. Getting our kids dirty is just one aspect of it. Our book explains how, from conception on, many decisions affect the types of microbes that kids encounter in the first years of life. Our diet during pregnancy, the mode of birth, the type of lactation and solid foods babies receive, the presence of pets at home and our everyday hygiene are all important in how kids experience microbes. It is through these exposures that the community of microbes that live inside of them, also known as the microbiome, forms and shapes important aspects of their health.

We freak out about babies putting everything in their mouths, but why are the microbes found on these objects especially important for babies?

During the first months of life, this microbiome develops through the different exposures a baby receives. Putting things in their mouths is only natural behaviour to taste the world and this includes microbes. If the object is safe (not a choking hazard) and it hasn’t been in contact with someone that is sick, or has fallen in a very crowded place (subway, mall, etc) it is safe for babies to put things in their mouths.

Is there a critical window for our kids to experience the health benefits of microbes?

Yes – the first 3 years of life are the most crucial with the very first year being the most important within those 3 years.

Can you give us some practical tips on what we should and should not to do to ensure our kids are being exposed to the health benefits of microbes?

In our book we cover many of these, with do’s and don’ts after every chapter but a couple of them are:
1. Get a dog (if you can have one, of course). Dogs bring the outdoors into your home and with that comes microbes. In fact, having a dog at home reduces the chances of developing allergies by 13%.
2. Encourage a good microbiome in your baby by feeding them lots of fiber. Microbes thrive on it so get rid of all refined grains (rice, wheat, etc) and substitute them for the “whole” variety. Add vegetables and fruits in every meal and also include fermented foods (kefir, yogurt, sauerkraut, etc) daily. There is no better way to grow a healthy microbiome than feeding it the right stuff.

What do you have to say to parents who are still concerned about dirt and germs?

Microbes are both good and bad buts most of them are good. As parents we can balance aspects to prevent disease, which is of paramount importance still today, with trying to unlearn hyper-hygienic practices that do prevent disease and are detrimental for our health. Hand washing is a good example of this: we should continue doing this, of course, but after we use the washroom, before we make or eat food, if we have been in a very crowded place, if we have been in contact with someone that has an infection or in contact with animal waste. Other than that, we should let kids be kids and encourage them to be outside, to get dirty and not clean them at the first speck of dirt.

If there was only one thing you could say about the importance of micrrobes it would be….

Microbes are part of who we are and looking after our microbiome early in life is one of the best things we can do for our children’s future health.

B Brett Finlay, PHD, is Professor of Microbiology at the University of British Columbia and has published over 450 articles on microbes and how bacterial infections work. A founder of the biotech companies Inimex, Vedanta, and Microbiome Insights, Brett is Officer of the Order of Canada – the highest Canadian civilian recognition. He lives in Vancouver with his wife who is a paediatrician and they have two adult children. Marie-Claire Arrieta, PHD, has been studying how intestinal altercations can lead to several immune diseases since 2007, combining her knowledge of microbes and immunology to lead a major clinical study on the role of the microbiota in asthma. A mother of two, Arrieta is a tireless advocate of using scientific knowledge to improve the health of children. For more information see

***The book Let Them Eat Dirt: Saving Your Child From An Oversanitized World is available to buy on Amazon.***

Image credit: Pixabay


  1. Oh I’m so glad you put this out there Talya. My kids are both super healthy. Since they were small they’ve been allowed to live like real little people and explore the world using all their senses. If they wanted to eat dog food with the fur babies, then we let them and I’m glad to say they are not lactose intolerant, have no allergies, can eat anything they want (they don’t do dog food anymore ) and only need to go to the doctor if they break something. In fact I can’t remember when last they had flu

  2. I don’t think i’m overly clean-conscious with the kids and they both seem to very rarely get sick, and if they do, it only lasts a day! My friend, on the other hand, is obsessed with keeping her home sparkling and the gastro bug which gave my boy a tummy ache for a day, took her little girl down so hard she was hospitalised for dehydration. The evidence speaks for itself! #coolmumclub

  3. And now I feel a lot better about my 9 month old’s habit of chewing on the end of our shoes/boots/slippers!!! Haha! her favourite is actually wellies, mmm dirt….I think it’s true though, we totally over sanitise more than we used to. Everything is anti bacterial! There was no such thing as hand gel what, 15 years ago? I went to Reading festival one year without it! (yuk!) but i live to tell the tale. #coolmumsclub

  4. I 100% believe this, we were brought up playing in the dirt, and I will be doing the same with Alfie. Whilst I do believe there are certain aspects of parenting that are outdated, and that we can do better, letting our kids being exposed to germs is one I will definitely still be doing. A great interview, thanks for sharing #coolmumclub

  5. Ive always thought this…I think being overtly sanitary can actually hinder your childs immune system and make them more frequently ill when they do encounter germs. I try not to stress myself out too much with cleaning my little man every single time I spy a tiny spec of dirt on him (same goes with the house actually) and I figure he will have a more developed immune system! <3

  6. Oh I am with you 100% Big fan of letting my kids play and have at it, dirt and all. We frequently play in the garden, and while we don’t have a dog, my inlaws do and we play their often. Here’s to spreading the word and letting kids live life, dirt and all! #coolmumclub

  7. Oh I do love the teeny tiny world going on right under our feet. There’s nothing prettier than a bit of mould under a microscope!
    I love microbes so much my mum still buys me a cuddly microbe each Christmas (and we have them hanging on our christmas tree). Mad scientist 😉
    Loving the sciency post, a welcome entry for #coolmumclub x

  8. I love dirt! Lucky for me so does my eldest, The Baby though, has a OCD issue and can’t have anything on her hands! eye roll! #coolmumclub

  9. I have often wondered if the “anti bac” movement is going to end up stripping our bodies of their own defences in the long run. We carry anti bac gel and wipes around and I know I’m guilty of washing my hands pretty much obsessively. Very good point and I’ll take it on board! Thanks for sharing x #coolmumclub

  10. I’m all for this. I think like most things, if you step back and look at it sensibly a bit of dirt is nothing to panic about. I did have to draw the line when L tried eating some random chocolate buttons from the street though, bleugh!! #coolmumclub

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