Bacterium in Dirt Makes Us Smarter and Happier

hands in dirtWhat do you know? It turns out digging in the dirt is even better for you than I thought. I love coincidences. Maybe it’s just the universe having fun with us, or maybe it’s a tool to help get a point across to us we might otherwise miss, were it not for those Twilight Zone moments. But just a few days after I wrote about those dreadful germ-killing paper towels, and how a little dirt can be good for us, I happen across the Canwest News Service article, “A little dirt could make kids smarter.”

While I addressed the strengthening and building of our immune-systems from little tests like contact with dirt, this article details 2007 research by British scientists into a natural soil microbe that actually “stimulates neurons in the brainstem to start producing serotonin.” That feel-good hormone that “has a number of different effects, but one of them is modulating mood and decreasing anxiety,” according to researcher Dr. Dorothy Matthews, associate professors of biology at The Sage Colleges in Troy, N.Y. Dr. Matthews was intrigued by this and she and colleague Dr. Susan Jenks conducted a number of ongoing experiments on mice, and their reaction to the inclusion or exclusion of this dirt microbe, mycobacterium vaccae.

colonies of mycobacterium vaccae in petri dish

Colonies of Mycobacterium vaccae in petri dish

While I’m not a fan of animal testing, and read something really horrific about testing still done by tobacco companies (and will be writing about it soon), this test seems pretty mild compared to most. One of the experiments involved feeding mice mini peanut butter and bacteria sandwich and seeing how long it took them to navigate a maze. How quickly they made their directional choices. The mice that got the bacteria-laced versions of the sandwiches ran the maze in half the time of the control group of non-bacteria exposed mice. “They also showed fewer anxiety behaviours – less freezing, wall-climbing, stopping and grooming, returning to the start, or defecation…In other words, they weren’t scared poop-less.”

Bu you know what struck me as really weird, and verging on cruel and unusual punishment? They made the sandwiches out of Wonder Bread. Then again, maybe they wanted something with near zero nutritional ingredients so as not to interfere with their results…

Further confirming the positive effects of this bacterium came when it was taken out of their diet. They began to revert to slower maze maneuvering. The effects seemed to steadily wear off, and after three weeks without any bacteria, there was almost no difference compared to the control group who never got any bacteria.

The good news? We don’t have to make ourselves PB and B sandwiches to get the benefit of this bacterium. Dr. Matthews says we are exposed to it just be being outdoors, near the soil. While she isn’t sure yet if the bacteria aerosolizes, “certainly if you’re vigorously working in the soil, there are probably some particles that are becoming airborne, so we may very well be inhaling it, as well as eating it by inhaling it and having it in our GI [gastrointestinal] tract.” It sounds like it’s a good idea to eat foods that grow close to the ground like lettuce and carrots. Guess Bug Bunny knew what he was doing.

It is worrisome though that in the last 100 years or so that urbanization has led to few people growing their own food and coming into direct contact with that good earth. Maybe that’ll be a side advantage to the fears around the security and availability of freshly grown food, and be another reason to grow a little of your own. Even with just a hanging basket of strawberries or cherry tomatoes, and a few greens in planter box, mycobacterium vaccae will be yours. Hey it sounds better than those bugs that live on our eyelashes…

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One Comment

  1. I remember having an argument with my grandmother about my young son playing in the dirt. She was a clean-freak and NO DIRT ALLOWED NEAR CHILDREN type person. I strongly disagreed as I have always thought natural immunity is built up by exposure. We need to get closer to our Mother Earth; every one should get down and dirty at least once a day!.

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