Eat dirt. You’ll feel better.

So suggest some researchers into eco-therapy, a trendy new concept that has doctors writing prescriptions for spending time in a park. While they don’t specifically recommend eating dirt (a pathological condition known generally as “pica”), they do say the soil contains mood-enhancing micro-organisms that enhance happy-making brain chemicals, such as serotonin.

The star of current research is the benign Mycobacterium vaccae, a micro-organism found in soil and discovered to enhance serotonin levels in mice.  Serotonin is the neurotransmitter du jour in psychotropic medications like Prozac and is known for its ability to alleviate depression and anxiety. (Mayer, et al.  “Gut Microbes and the Brain:  Paradigm Shift in Neuroscience”. The Journal of Neuroscience. 12 November 2014, 34(46))

I practiced eco-therapy long before science discovered it. I’ve been a river rat since childhood.  After leaving home, I wound up in New York, but two years of noise, bad smells, pollution, too much concrete and pavement drove me to the opposite extreme—the mountains of Colorado– in 1977.  After some bouncing around, I moved to another big city, Atlanta, in 1992 for career training and lived there three years.  I spent all my free time in the back yard, planting flowers.  Because of the garden, the house sold for much more than the realtor believed I could get.  So my eco-therapy was financially rewarding, too.

I spent too many years after that working in offices, often with no windows or with windows fronting on parking lots, and missing the best part of the day outside. Now retired and living on the old family homestead, I spend as much time as possible outside, scratching in the dirt with my chickens, and surrounded by the greens and blues of nature.  I’ve always liked the smell of earth, and now science is telling me why.

The scientific community is discovering what humans have instinctively known forever. In “The Nature Cure:  Why some doctors are writing prescriptions for time outdoors,” by James Hamblin, MD (Atlantic magazine, October, 2015) tells of the emerging “eco-therapy” concept. Dr. Hamblin writes of the M. vaccae. He also references a UK study showing physical activities in natural versus “artificial” environments, induced less anger, fatigue, and sadness.  Another study found that patients recovering from gall bladder surgery fared better if they were in rooms facing trees instead of a wall.

“The Nature Cure” also cites research that says people are attracted to and feel restored by looking at images of nature, especially savannas, slow-moving water, foliage, and “birds or other unthreatening wildlife.”

Since then, I’ve stumbled on similar articles about the healthful and mood-enhancing effects of nature in Yes! magazine and Mother Earth News.  The winter, 2016 issue of Yes! is devoted to creating a “culture of good health.”  In “The Curious Case of the Antidepressant, Anti-anxiety Backyard Garden,” family practitioner Dr. Daphne Miller says “It’s well-established that the microbes in soil enhance the nutritional value of food and, as found in studies of farm children in Bavaria and among the Indiana Amish, improve immune function.  (Researchers were finding that exposure to a diversity of microbes early in life led to fewer allergies.)”

Dr. Miller states we need a diversity of organisms found in animals, plants, soil, water, and air for optimal functioning of our immune and nervous systems. She laments the modern practice of crop monoculture and use of pesticides and herbicides, which all deplete soil of micro-organism diversity.

Finally, “Nature Really Does Make Us Happy,” by Eva M. Selhub and Alan C. Logan, in the December, 2015/January, 2016 issue of Mother Earth News, takes a slightly different tack.  Here, behavioral scientist Roger S. Ulrich is given credit for the original research on gall-bladder patients.  He is also given credit for a landmark 1979 study on stressed students.  He showed them images of nature scenes and cities.  “The nature scenes increased positive feelings of affection, playfulness, friendliness and elation.  Urban views, on the other hand, significantly cultivated one emotion . . . sadness.  Viewing nature tended to reduce feelings of anger and aggression, and urban scenes tended to increase these feelings.  Also, seeing natural landscapes was associated with increased production of serotonin,” say the article’s authors.

Other studies cited in the Mother Earth News article indicated elderly inhabitants of a residential care center in Texas had lower levels of cortisol (a stress hormone) when in a garden rather than a classroom.  The presence of plants, particularly flowering ones, in a room can reduce stress caused by an emotional video.  In Taiwan, rural farm scenes produced higher alpha-wave activity, particularly in the right brain.   Alpha-waves are associated with peaceful states of mind.  Forest scenes and natural water scenes also decrease heart-rate.  In Japan, forest walks reduced cortisol levels.  Forest walks are also credited with reducing depression and hostility, while increasing vigor and improving sleep.

Norwegian research shows that having a plant near or within view of a work station significantly reduces the amount of sick leave workers take. Japanese research adds that greening high-school classrooms with potted plants significantly reduces students’ visits to the infirmary.  Nature scenes fired up opioid receptors in subjects’ brains, imaged by fMRI in California.  Endogenous (produced by the body) opioids reduce perception of stress, enhance emotional bonding, and decrease brooding over negative memories.  Urban scenes were found in Korea to activate the amygdala, a part of the brain associated with anger and fear.  Chronic stress and cortisol may promote activity in the amygdala, which selectively prioritizes memorization of negative experiences and events.

So there you have it. My take-home message is to escape as often as possible the boxes where we live, drive, and work, and to enjoy the health-sustaining multi-dimensionality of the great outdoors.

Photos, top to bottom:  Camellia;  White-tailed deer;  Trees and marsh;  Pecan tree with Spanish moss; Moon River at high tide.