“Let Them Eat Dirt” – A Followup!

A few months back, I did an appearance on “Daytime“, which is the local daily morning show for the Ottawa area.  We discussed the most important germ concerns facing the public and part of it was the ‘hygiene hypothesis’, one of my favorite topics.

I am not sure why, perhaps I didn’t take my probiotics that day, but for some reason, when I was discussing the idea that kids need to play outside and become exposed to the environment, I happened to clump in the concept of letting them eat dirt.

You can watch the video below and if you wish, skip to 5:30-5:40 – it’s a hoot.

It’s also here: http://www.rogerstv.com/page.aspx?lid=237&rid=4&gid=81426

Well, today, I was happy to see a very interesting link in my Inbox that might have finally brought me redemption.

The article is called:

Restricting Microbial Exposure in Early Life Negates the Immune Benefits Associated with Gut Colonization in Environments of High Microbial Diversity

and it is published in Open Access Journal PLoS ONE.  If you wish to read it, you can find it here:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028279

The article focuses on pigs rather than humans but the outcomes are fairly similar to what would be expected.

The authors state:

“…strong environmental and immune-related selective pressures drive events which shape the microbiota, but importantly, this stabilization process requires continual microbial exposure throughout development. In this study, the isolation of piglets shortly after birth restricted subsequent environmental microbial exposure. Consequently, the bacterial subsets colonizing the gut throughout the experiment were mainly acquired during the first days of life. Microbial expansion and high diversity was seen in both isolator groups after weaning, and suggests that succession and stabilization of the mucosa-adherent microbiota was significantly impaired by isolation of these animals.”

What that means for you and me is that diverse exposure to microbes both in the prenatal as well as the postnatal stages is important for maintaining a healthy immune system.  Furthermore, this highly diverse microbial exposure tends to lessen as a child ages into adulthood, eventually settling on a set of microbes that are tolerated and those which are, well, just not liked.

More importantly, if those tolerated microbes don’t jive with the environment whether it be food, air, water or chemicals, then exposure to them might make the immune system go a little haywire.  This could end up as allergies, atopies, conditions such as IBD, or in some cases, shock.

So…with all that said:

  • Considering our increasingly germaphobic nature (ironically, against the wrong germs), there may be an answer behind the huge increase in these problems over the last 50 years.
  • Those who have been brought up in highly diverse microbial environments (such as farms and rural areas) may have less problems overall.

  • In urban areas where exposure is usually isolated, one can still get their microbial exposure by visiting a farm.  Based on the reading I’ve been doing, pregnant mothers should visit farms especially in the later stages and then take their children there while they are still young. 

Finally:

 I feel justified for saying that children should eat dirt!!! 

Okay, I appreciate that for some, the concept of a mud sandwich may not be the best choice for lunch or that mid-afternoon snack, but if a young child opts for that nutritional choice, don’t get upset or even sad.  Just think to yourself:

“I’m helping them develop a great immune system.”

If that doesn’t work, well then, just blame it on me.

Would love to hear your thoughts.

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2 Responses to “Let Them Eat Dirt” – A Followup!

  1. Julia Serradilla says:

    Totally agree: My mother overprotected me from germs so much, that not even my grandparents could kiss me, and when I started to do “normal life”, I became asmathic and the doctor said that was the reason.
    I compare my relatives who live in the city with the ones who live in farms, and my octogenarian uncles are much healthier than them; never knew they had even a cough!

  2. Alec Duncan says:

    I’m firmly convinced that children aren’t getting enough exposure to dirt and that it is harming their immune systems. It’s not just the excessive use of germicides in situations that do not warrant them, it’s also that children are spending vastly less time playing outside than they used to. If young children are inside watching TV or playing video games, or only playing in playgrounds with artificial surfaces, how are they going to get the necessary exposure to diverse microbiota? Rates of outdoor play have dropped catastrophically over the last 30 years.

    When I was studying early childhood education back in the early 90s one of the lecturers mentioned a study that she said showed that the average healthy toddler ate around 30grams of dirt every day without ill effect. This wasn’t in response to the hygiene hypothesis – she didn’t claim the study showed any benefit to eating dirt – she was just using it to calm some students’ fears about children eating dirt. Have you ever come across this study?

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