Arboretum News

Soil = Health

Microbes in soil help build the nutritional value of fruits and vegetables, and they might be beneficial to human health, as well.

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Planting grapes at the Horticultural Research Center last June. Photo by Chris McNamara.

By Jean Larson, manager of Nature-Based Therapeutic Services Program at the Minnesota Landscape Arboretum

We know microbes in soil help to build the nutritional value of fruits and vegetables. But did you know there is a microbe in soil that is tied to the development of our immune and nervous system, and even our mental health? Introducing Mycobacterium vaccae or M.vaccue for short.

Scientists like Jill Litt, an assistant professor at the University of Colorado School of Public Health, are studying the impact M. vaccue has on a variety of health outcomes—including mood disorders. In addition, she studies how gardening benefits us because of how it creates community, encourages physical activity, offers a bounty of nutrient-rich food, and exposes one to Vitamin D-producing sunshine, which helps regulate serotonin,  (a.k.a. the “happiness” neurotransmitter). This kind of research is especially important now during COVID-19 as we find ourselves at the cusp of gardening season while isolated and social distancing from family and friends.

This compelling initial evidence suggesting that digging in the soil (gardening) is beneficial to human health and well-being is based on how we have been co-evolving with M.vaccue since the beginning of our earliest days. But in addition to M.vaccue there is an enormous palette of other microbes that we have been interacting with throughout time. Research suggests our immunological and psychological well-being most likely depends on more early and frequent exposure to a diversity of bacteria, fungi, protozoa, and worms than it does on any one organism. Therefore, the jury is still out on M.vaccue. One thing we do know for sure is science indicates we need diversity of microbial organisms for optimal functioning of our immune and nervous systems. 

For us that means the best place to begin nurturing the diversity of microbial organisms is within the soil in your own backyard plot, raised bed or window box. That is why I am suggesting this year to plant with the intention of benefiting soil and for more diversity in your garden.  To nurture and care for your garden:

  • plant a variety of seeds
  • find alternatives to garden chemicals
  • build a compost pile and nourish the soil with rich organic matter

Finally, take off your garden gloves to feel the soil that gives life to your vegetables and pay well-earned gratitude to these old microbial friends we have coexisted with over time and who sustains our life today.

1 comment on “Soil = Health

  1. Mary Yee

    Thanks for this article; so interesting. This is more evidence that all of us, including our small children, would benefit from gardening.

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