Along with the benefits of diet quality from access and consumption of clean, fresh produce are the therapeutic benefits of gardening and horticulture. Researchers are discovering that growing your own food--however much or little you can do--is better for your health than anyone ever suspected. And the nutritional value of what you harvest is almost the least of it. Growing your own food by messing around in a garden proves to be nature's fruitful way of cultivating your health--physically and psychologically. Call it soil-borne wellness, and here is where science is plowing totally new ground. The soil is a rich repository of microbes and other organisms with which we've coexisted from the beginning. As science digs deeper into understanding the effects of bacteria on human health, and especially on the immune system, it looks increasingly like ingesting components of the soil itself might be as critical to human health as the very finest fruits and veggies grown in it. Mycobacteria vaccae thrives in typical backyard garden environments or anywhere soil is enriched with organic matter. A person is exposed to it through inhalation and ingestion of small particles any time you dig outside or eat lettuce plucked from a garden. Researchers argue that M. vaccae triggers a complex cascade of neurosignaling that stimulate immune cells to raise the threshold for inflammatory processes. Mycobacteria also interact with the nervous system to rev up production of serotonin. It's known that the SSRI antidepressants such as Prozac inhibit the reuptake of serotonin, increasing its availability to receptors. But exactly how these drugs work against depression, and their many undesirable effects on the body, are poorly understood. Many scientists regard the SSRIs as particularly blunt instruments for treating mood disorders. By contrast, research has found that mycobacteria are very selective and specific. They excite small subsets of serotonin-releasing neurons and pathways in the prefrontal cortex and hippocampus, where they directly impact cognition and mood regulation.
Getting out in the garden plants us back in what now appears to be our optimal habitat. Eating fruits and vegetables--even antioxidant-rich tomatoes, melons, beets, cabbage, and berries--turns out to be only half of a newly evolving story of health. Our bodies and brains depend on the whole experience of growing our own. Our mental and physical health seems to be deeply rooted in the dirt.