If you spent time squishing your toes in the mud as a kid or if you garden today, you know how fun gardening can be. But could gardening be the new Prozac? According to Dr. Christopher Lowry, director of the Behavioral Neuroendocrinology Laboratory at CU-Boulder, it’s a possibility.
Soil Bacteria: The Magic of Mycobacterium Vaccae
Gardening could help as an antidepressant, but not just because we're getting good exercise and sunlight. It also exposes us to special soil bacteria. In a study led by Dr. Lowry, researchers injected mice with Mycobacterium vaccae, a common soil bacterium. He and his team found that M. vaccae “activates brain serotonergic neurons, and increases serotonin in the medial prefrontal cortex.” In other words, M. vaccae “has antidepressant-like behavioral effects in mice.”
M. vaccae helped in more ways than one, though. The treatment also resulted in “stress resilience effects.” It effectively inoculated mice against stress-induced colitis, IBS, and anxiety. In general, M. vaccae has anti-inflammatory effects. According to Dr. Lowry, "Increasing evidence suggests that inappropriate inflammation is a risk factor for mental health disorders, including trauma-associated, anxiety and affective disorders.” If soil bacteria can reduce inflammation, it can also reduce the development of numerous mental health issues linked to it.
One reason researchers are studying soil bacteria can be found in the hygiene or "old friends" hypothesis. The "old friends" hypothesis suggests that a lack of exposure to immunoregulatory microorganisms like M. vaccae is driving today's epidemic of inflammatory disease. In basic English, we have gotten too clean for our own good. Now, we may need to get dirty more often - for our health.
The Latest Research on M. vaccae
Dr. Lowry won't make claims that haven't been backed by evidence yet. As he says, “We don’t yet know that exposure to mycobacteria through gardening is sufficient to have effects on emotion and cognition."
While Dr. Lowry doesn't say gardening will be able to replace drugs like Prozac, he is researching its potential. One of his latest projects looks at the effects of M. vaccae when present in an aerosol. According to Dr. Lowry, “This work should give us some indication of concentrations of M. vaccae in aerosol that are sufficient to modify human behavior.” Hopefully, this study will show how much M. vaccae it takes to positively affect us in the same way the injection affected mice.
We know you can find M. vaccae in soil, but could you find it in your own garden? Noah Fierer, lead investigator in the Department of Ecology and Evolutionary Biology at CU-Boulder, is researching that question, too. He and his team are researching the distribution of M. vaccae and other mycobacteria in soils around the world.
According to Dr. Lowry, the results of both of these research endeavors could be available within the year. To stay up to date on their findings, you can follow Dr. Lowry on Twitter.
The Future of M. vaccae in Medicine
Dr. Lowry believes that one day M. vaccae could be used as a “prophylactic intervention to suppress inappropriate inflammation and reduce the risk for inflammatory disease, and mental health disorders in which inflammation is a risk factor.”
Maybe one day, soil bacteria will help inoculate us against mental health problems like depression, stress, and anxiety. Maybe our doctors will simply begin to prescribe more time outside digging in the dirt. While it’s too soon to say that gardening is the new Prozac, it certainly couldn’t hurt.
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