Dirt Is Actually Good for You: Who Knew?


When Ma scolded you for getting dirty playing in the yard, claiming you’d probably catch some vile disease, she was probably wrong. In fact, recent studies are showing that getting your hands (and feet!) dirty is actually good for you.

A bacteria naturally found in soil and dirt almost everywhere on the planet, Mycobacterium vaccae, actually activates the release of serotonin and dopamine in your brain. Dopamine affects your emotions, stimulating feelings of pleasure and dulling pain, while serotonin regulates your humor, social behavior, libido, memory and sleep. So, when you come indoors after gardening feeling refreshed, it’s quite possible a soil bacterium is the cause.

Scientists suspect that M. vaccae is not aloneThat other common soil bacteria may also contribute to the feeling of well-being that gardening gives. So, more joy, improved relaxation and less pain, and all this without the side effects and risk of chemical dependency of pills like Prozac.

Such antidepressant microbes in soil are also being studied for improving cognitive function, controlling Crohn’s disease and helping to treat rheumatoid arthritis.

An Accidental Discovery

Mycobacterium vaccae. Photo: Christopher Lowry, University of Colorado, Boulder

This was discovered accidentally when oncologist Dr. Mary O’Brien tried administrating killed M. vaccae to boost the immune system of patients suffering from lung cancer, but the results went well beyond what she expected. Not only did it indeed stimulate their immune system, as she hoped, but patients reported feeling happier and more energetic and experiencing less pain.

According to a later study by neuroscientists Dorothy Matthews and Susan Jenks, tests on laboratory mice show they are less anxious and more relaxed after treatment with M. vaccae. In fact, they even seem to be smarter, finding their way through a maze twice as fast as untreated rodents. The effect is lasting, too, still present two weeks later.

When you garden, you absorb beneficial microbes through your skin and through your lungs as you breathe. 

So, what are you waiting for? Get out outdoors and garden! Preferably barefoot and certainly without wearing gloves!

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

6 comments on “Dirt Is Actually Good for You: Who Knew?

  1. There’s a saying in the American South: ‘A child’s not finished until it’s eaten a peck of dirt”. Bon appetit!

  2. Can you provide some clinical evidence on the following assertion? “When you garden, you absorb beneficial microbes through your skin and through your lungs as you breathe. “

  3. You don’t need to convince me.

  4. Pingback: Why Your Plants Make You Happy – Laidback Gardener

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