I remember, as a kid, frequently coming home from a days’ play in the garden, the park or the street, covered in mud and muck from head to toe. My mother would complain that it seemed to be impossible for me to have fun without getting completely dirty! The only plausible explanation I could ever come up with was that it was “fun”.
Even today, as a grown man, I still thoroughly relish the messy enjoyment of a soccer match on a rainy day and a muddy pitch. These days, however, I can explain my enjoyment of getting messy with scientific rationality: it’s good for me! Researchers have shown that the dirt and the bacteria that inhabit the great outdoors are actually healthy.
The hygiene hypothesis
Scientists have argued for some time that the sharp rise in immune system disorders like asthma, allergies, inflammatory bowl disease, multiple sclerosis and Type 1 diabetes during the last century, particularly in the developed world, stems from an unhealthy obsession with clean living. Dr Joel V. Weinstock, the director of gastroenterology and hepatology at Tufts Medical Center in Boston argues that at birth our immune system “is like an unprogrammed computer. It needs instructions.” He says that “children raised in an ultra clean environment are not being exposed to organisms that help the appropriate immune regulatory system develop circuits” which can tell good bacteria from those that are harmful.
Some scientists are even suggesting that the instinctive way in which many babies taste and eat dirt is an evolutionary behaviour that gives their immune system a kick-start in exploring their environment. Bacteria are everywhere: around us, on us and inside of us. Each human being typically plays host to about 90 trillion microorganisms, many of which are essential to our health.
Bacteria are good for you
Recently scientists have discovered that bacteria which naturally occur in soil have a number of health benefits. Exposure to Myobacterium vaccae, a common soil microorganism, can increase learning behaviour. Mice that were fed Myobacterium vaccae were able to negotiate mazes twice as fast and with less anxiety than control mice. The bacteria also seem to be able to alleviate skin allergies.
Lung cancer patients who were injected with dead Myobacterium vaccae reported better moods, less pain and nausea and a better overall quality of life even though their survival time was not affected. Myobacterium vaccae is believed to have an effect similar to that of antidepressant medications like Prozac.
So get out into nature as often as you can to make sure you get a regular dose of dirt and muck. And the next time your mother, wife or girlfriend complains about you getting filthy outdoors, tell her that you do it because it makes you smarter, happier and altogether more healthy!
Some of the world’s more adventurously experimental chefs have really taken the dirt-is-good-for-you mantra to heart and are using “imitation” dirt made of dehydrated beets, berries and mushrooms in their dishes. Spain’s Joan Roca of El Celler de Can Roca restaurant and Yoshihiro Naisawa of Tokyo’s Les Crétions de Narisawa go as far as “distilling” soil and incorporating the “essence” into their dishes.
The book to read
Why Dirt Is Good: 5 Ways to Make Germs Your Friends by Mary Ruebush