Let Kids Eat Dirt: Over-Cleanliness Linked to Heart Disease

By Andrew Moseman | December 11, 2009 1:15 pm

baby-dirtThis week brings more vindication for a childhood full of bumps, bruises, and going outside, rather than sterile modern living. In a long-term study published in The Proceedings of the Royal Society B, U.S. researchers suggest that over-cleanliness could make babies more prone to inflammation later in life, and in turn raise the risk for stroke and heart disease.

Thomas McDade’s team studied more than 1,500 people in the Philippines who had health surveys at age two and then again at age 20. The team tested them for C-reactive protein (CRP), a marker of inflammation. They found that the more pathogens the people had encountered before age 2, the less CRP they had at age 20. Every episode of diarrhoea back then cut the chance of higher CRP later by 11 per cent; every two months spent in a place with animal faeces cut it by 13 per cent. Being born in the dusty, dirty dry season cut the chance by a third [New Scientist].

McDade chose the Philippines to test the idea that a dirty childhood leads to a healthier adulthood because the particular area lacked Western-style sanitation. The Filipino children thus had more infectious diseases than American kids, but their adult CRP was 80 percent lower. The research suggests that inflammatory systems may need a higher level of exposure to common everyday bacteria and microbes to guide their development [UPI].

The finding are another boon for the “hygiene hypothesis“—the idea that our sanitized world fouls up people’s immune systems (which evolved to deal with a germy environment), and makes people more prone to allergies, asthma, and more ailments. It also backs up a Nature Medicine study from last month which showed that over-cleanliness hindered the skin’s ability to heal.

So, McDade says, parents should develop a healthy medium between letting kids get dangerously sick and raising them in a nearly sterile environment. “In the U.S we have this idea that we need to protect infants and children from microbes and pathogens at all possible costs. But we may be depriving developing immune networks of important environmental input needed to guide their function throughout childhood and into adulthood” [LiveScience].

As for CRP, the Wall Street Journal says you might be hearing its name more frequently as the pharmaceutical giants move toward drugs for people with high levels.

Related Content:
80beats: Doc Diagnoses Our Nut-Phobic Society with Mass Hysteria
Discoblog: Let Them Eat Dirt! It Contains Essential Worms
DISCOVER: Asthma and the Curse of Cleanliness

Image: flickr / deanj

CATEGORIZED UNDER: Health & Medicine
  • rRootagea

    Wasn’t there some article a while back about sniffing dirt to cure depression?

  • http://n/a Debbie

    When we were little, we would “steal” sugar from Mom’s kitchen, take it outside, mix it with mud, then “bake” on top of the steel sistern lid. We thought they were delicious.

    As you can tell, I survived, but if I had caught my kids doing that, I don’t know what I’d have done, except be mad that they “stole” the sugar!

  • http://www.freewebs.com/stonerbitch Veronica

    I used to love touching ants, spiders… everything that moved when I was a kid. Hopefully I’m well ‘equipped.’ But now I’m a neat freak. I can hardly touch the remote and then my food. I should go back to the good old dirty ways. lol.

  • JJ

    I do remember an article about how gardening (and hence exposure to dirt) potentially lessened the symptoms of depression. I can’t remember what the critical factor was in the dirt, however. Some microbe I think.

  • Carrie

    Although I think there’s some merit to this hypothesis, urban parents should be aware that dust and dirt can be heavily contaminated with lead. Lead has been proven to cause long-term impairments in cognitive function, even at levels well below what is considered “elevated.” Go to the CDC website for more information, but it’s probably best that children growing up in cities not be allowed to eat dirt.

  • Jim P

    We I was a kid we were told you have to eat a pound of dirt before you die. I’m 83 years old and I have no idea how much I’ve eaten, but I certain it’s more than a pound, if you consider most impurities as dirt.

  • scott

    lol. I always knew my parents’ compaints about how dirty I got were misfounded!

  • Rachel I

    I found myself smiling while reading this article.

    I had a “normal” childhood by Philippine standards– I used to roam our backyard and our peaceful little neighborhood playing with stones, sticks, bottle caps, elastic bands, slippers and everything else. (This was about 18 years ago when there were no electronic gadgets to play with.)

    Unknown to my parents (who were at work during the day), I had grand afternoons boiling some unknown leaves at the backyard using a small tin can for sardines.. and also have come to know how pebbles and my toes tasted like. LOL.

    But, I never got seriously sick due to “germs”. I guess this is true after all, too much cleanliness is not good for the health.

  • Kelvin

    According to this article, every time we wash our hands we are actually hindering our immune system and skin healing. Always wondered why I scar more now than I did as a child. Here I was thinking aging was the only culprit when taking more showers (in chlorinated water no less) than I did as a child, is to blame. I remember a story my cousin, who lived in the Dominican Republic for over 30 years, told me. He mentioned that most people there could not drink the tap water without getting a serious case of the runs. The only people who do without consequence are the really poor, who have been doing so since birth. As a joke he said that those people could lick the floor under a public toilet and not get sick, whereas the rich would more than likely die. I believe its time to take the kids to the local farm for the day as often as possible to secure a healthy future. Seems like the steps we’ve been taking to protect ourselfs from germs and such, are in fact ensuring sickness. How is that for a smack in the face of most medical establishment.

  • http://clubneko.net Nick

    As always, everything in moderation. Don’t run out and stick a bleeding wound into the dirt to ‘cure’ yourself.

    Don’t stop washing your hands…. just make sure they’re truly dirty in between washings. I stick my hands in my mouth all the time, and I’m healthy as a horse, and probably wash them 2 to 4 times a day.

    At the same time, if you’ve never lived like that don’t change immediately… ease yourself into it.

  • http://discover James

    So maybe all that nail biting I did as a kid was a good thing. He he he. Just goes to show that you shouldn’t try to change human nature. Everything is done for a reason whether you know it or not. I think I’ll chew on one of my nails right now. LOL.

  • Arshad

    Well it is something very intresting that the new findings aprove what we (older people) always used to say that children in the past, say 50 years ago, did not used to get ill as much as today’s children. I even experienced it when I moved to Europe to study when I was 17 from third world country finding some illness such as asthma and …so frequent within the students and alway thought they were so much more vulnerable to disease.
    But the only thing is that it is not only the cleanness that attributes to this, it may be that the great amount of pollution of our enviroment also play a major roll as well.

  • http://crowlspace.com/ Adam

    As kids I think we tried just about everything – from sucking on stones, tasting bits of metal (not swallowing), playing with/in raw clay, and swimming in creeks and rivers (unpolluted). Considering how much mud I’ve probably swallowed… I can’t imagine. I’ve only ever run afoul of soil bacteria once, while gardening and being stabbed by a buried root. Nasty infection travelled up my arm before I went to a doc for antibiotics. Later it became a nasty case of cellulitis – and another dose of antibiotics. Yuck!

  • http://blogs.discovermagazine.com/80beats/ Eliza Strickland

    Jim P: Yeah, my southern parents often said that every kid would eat a peck of dirt. It was their way of saying, don’t try to protect your kid from every little thing — but it’s also a nice example of folk wisdom!

  • YouRang

    No one seems to have mentioned the possibility that the kids who can lick a toilet seat can do so because the vast majority of their siblings who also licked toilet seats ARE NOW DEAD and they just were lucky enough to get just the right dose of germs and genes.
    As someone above did mention–Everything in moderation.
    Counter example. My mom’s mom was more into cleanliness than my dad’s; but my mom had no allergies, but she did have migraines.

  • Emma

    I am 73. As a child, I spent most of my time outdoors and heaven only knows what I came in contact with and/or ate. I do remember regularly eating ice chips from the back of the truck delivering ice to the neighborhood (we had an icebox, not a refrigerator) and which was the same truck that was used to deliver coal in the winter, making mud pies (and probably eating them), and leaving home after breakfast only returning to use the bathroom or for meals with the time in between happily used for playing. I played in the woods, at/in the creek, with domestic and farm animals, caught turtles and tadpoles, went to the dump (what landfills were called then) to find things to play with such as an old car top to turn upside down and use as a raft to ride the “rapids” of the creek. Saturdays were special because a neighbor lady made fresh bread and all the kids in the neighborhood would stop by for a slice still hot, buttered and sprinkled with sugar (no we didn’t wash our hands before eating it and we may have just come from playing most anywhere with most anything.) I could go on and on because we didn’t have anything electronic and our days were spent outdoors in good weather and often even when the weather wasn’t good. I am 73.

  • http://www.activesecuritytraining.com/Location.html guard card california

    Do you have more specific information you could post about on this subject? Would be awesome. Thanks!.


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