Gardeners are extremely proud of their hobby, and they are constantly claiming that it has numerous benefits for them. Apart from the fresh air, sunlight exposure, and physical exercise, they claim that working in the garden reduces stress and improves their mood.

Well, scientists agreed with them. Apparently, gardening can help us combat depression, due to the antidepressant microorganisms found in the soil.

Dirt and soil contain Mycobacterium vaccae (M. vaccae) that naturally activate the serotonin and dopamine release in the brain.

While working in the garden, we absorb these microorganisms into the skin and inhale them while breathing. When they enter the bloodstream and respiratory system, they improve mood and relieve pain.

Dopamine affects emotions through sensations of pleasure and pain, while serotonin regulates mood, sleep, social behavior, libido, and memory. Low serotonin levels have been linked to anxiety, depression, bipolar issues, and obsessive-compulsive disorder.

The antidepressant bacterium found in soil has no adverse health effects, and it may be as easy to use as just playing in the dirt.

This discovery was accidental. In 2004, Dr. Mary O’Brien, an oncologist at the Royal Marsden Hospital in London, administered M. vaccae to boost immunity in lung cancer patients.

O’Brien explained that bacteria boosted the immune system, but also relieved their pain and boosted their vitality and happiness. She wrote that the bacteria injection “significantly improved patient quality of life.”

Neuroscientist Christopher Lowry at Bristol University tested the effect of M. Vaccae on mice behavior in stress tests and discovered that those mice that were inoculated with the bacterium were less anxious and performed better in tests.

He maintains that M. vaccae activated the neurons responsible for the release of serotonin production and others that affect the immune system.

Neuroscientists Dorothy Matthews and Susan Jenks conducted a study on mice whose findings were published in the Behavioral Processes Journal, and suggested that “eating, touching and breathing a soil organism may be tied to the development of our immune system and nervous system.”

They administered M. vaccae and conducted behavioral tests that showed that the mice were less anxious and had improved cognitive functioning.

Matthews explained that “it is interesting to speculate that creating learning environments in schools that include time outdoors where M. vaccae is present may decrease anxiety and improve the ability to learn new tasks.”

Professor Graham Rook at the University College London suggested that the gastrointestinal tract is the home to a hundred trillion microbes, that result from both, genetics and lifestyle, and interact with the entire body.

He claims that deficiencies in microbial exposure are the cause of the rise in chronic health problems, including depression. This brain-gut link is the connection between gardening and mental health.

Our ancestors lived with bacteria, fungi, and parasites for centuries.

Emeran Mayer, a gastroenterologist and neuroscientist at the University of California-Los Angeles and author of The Mind-Gut Connection, says:

“We’ve forgotten that these were beneficial. They might have caused an initial infection, but could then live in symbiosis with us. Many of these organisms evolved alongside humans, and likely the entire line of mammals we descended from, too. The benefit we got was that we had a much more clever immune system that didn’t attack our own selves.”

So, go outside, start a garden, and reap all the benefits of gardening!