Nature’s Antidepressant – How working with the soil might boost your spirits

Have you been looking for an excuse to get your hands dirty? If so, here it is!

In 2002, Graham Rook and Laura Brunet published an article called “Give us this day our daily germs,” in which they argued that our modern-day lifestyles in wealthy countries, including both hygiene and antibiotics, have reduced our exposure to organisms, such as mycobacteria, that live in soil and water.

This reduced exposure, they suggest, is improperly activating our immune systems, resulting in higher rates of allergies and disease. And in the past ten years, many researchers have become interested in the ways that the human immune system is triggered by the world outside our bodies.

Bacteria improves quality of life in cancer patients

Of particular importance are some of the studies examining the effects of Mycobacterium vaccae (M. vaccae)—a strain of bacteria commonly found in soil. For example, while testing the effects of heat-killed M. vaccae on lung cancer patients receiving chemotherapy, oncologists made an unexpected discovery: 

The bacteria did not seem to affect patients’ survival rates, but patients did report an improved quality of life, including better cognitive function and a sense of vitality, as well as some relief of both the chemotherapy-related treatment symptoms and cancer symptoms. 

Bacteria in soil triggers release of serotonin 

Serotonin is vital to nearly all of our physical and behavioral processes, including mood regulation, and many common antidepressant drugs are designed to affect serotonin levels.

Neuroscientists at the University of Bristol decided to investigate the oncologists' findings further, and discovered that heat-killed M. vaccae altered emotional behavior in mice. Specifically, the bacteria produced antidepressant-like effects by triggering neurons in the brain to produce serotonin.

Chris Lowry, lead author of the University of Bristol study, in his conversations with the media, noted that such studies are leading to a better understanding of the connections between healthy immune systems and mental health. “They also leave us wondering if we shouldn’t all be spending more time playing in the dirt,” he also said.

Which leads me to ask:

Have you had your dose of M. vaccae today?

Stay tuned for my next post about how regular contact with M. vaccae might also make you smarter...

References

Lowry, C.A. et al. (2007). Identification of an Immune-Responsive Mesolimbocortical Serotonergic System: Potential Role in Regulation of Emotional Behavior. Neuroscience 146, 756-772.

Medical News Today. (2007, April 2) Soil Bacteria Work in Similar Way to Antidepressants. http://www.medicalnewstoday.com/articles/66840.php

O’Brien, M.E., et al. (2004). SRL172 (killed Mycobacterium vaccae) in addition to standard chemotherapy improves quality of life without affecting survival, in patients with advanced non-small-cell lung cancer: phase III results. Annals of Oncology 15(6), 906-914.

Rook, Graham and Brunet, Laura. (2002). Give us this day our daily germs. Biologist 49(4), 145-149.

Military Veterans and the Outdoors

A few weeks ago, I was excited to learn about a new study involving military veterans and the outdoors, conducted by researchers Jason Duvall and Rachel Kaplan at the University of Michigan’s School of Natural Resources and Environment.

The results? Veterans who participated in outdoor programs—specifically multi-day camping and hiking trips—reported an improved sense of mental wellbeing, as well as feeling less socially isolated. (In the interest of full disclosure, the study was funded by the Sierra Club, which runs the Military Family and Veterans Initiative, an outdoor program for veterans and their families.)

I was not surprised by the results—they align with what I hear every day from the veterans I talk to: that being in nature—whether it’s camping, hiking, biking, canoeing, fishing, farming and gardening, or spending time with animals such as horses and dogs—is helping them to manage their post-traumatic symptoms, and to feel more connected to their communities and life in general. And in many ways, the study’s results parallel the other research I’ve been writing about in this blog.

But a common problem I hear from veterans is that despite their anecdotal reports, there’s very little funding available for these types of activities. And why is there no funding? Because according to the funders (not the veterans), there’s no proof that these activities work(!).

So that’s why this study is exciting. It focuses specifically on veterans, and provides the numbers and proof that funders require. In fact, the reason the Sierra Club sponsored this research was to study whether their Military Family and Veterans Initiative and similar programs were benefiting veterans. From the anecdotal stories of veteran participants, the Sierra Club knew that their programs were important, but hoped that quantitative analysis and results would further support their work.

Most interesting? Many of the veterans continued to experience an improved sense of wellbeing a month after their excursion, and those who were suffering the most seemed to report the most improvement. The researchers acknowledge that more studies are necessary, but this one, at least, is a start.


References:

Duvall, Jason and Rachel Kaplan. (2013). Exploring the Benefits of Outdoor Experiences on Veterans: Report prepared for the Sierra Club Military Families and Veterans Initiative. Retrieved from:

http://www.sierraclub.org/military/downloads/Michigan-Final-Research-Report.pdf

U-M study of veterans finds links between outdoor activities, improved mental health. Retrieved from:

http://ns.umich.edu/new/releases/21605-u-m-study-of-veterans-finds-links-between-outdoor-activities-improved-mental-health

U-M, Sierra Club to study links between outdoor experience, veterans’ mental health. Retrieved from:

http://www.snre.umich.edu/news/01-30-2012/um_sierra_club_to_study_links_between_outdoor_experience_veterans_mental_health