Our first meeting was on a bus in Tokyo, Japan, in 2003. We began talking about the influence of mindfulness and natural environments on human health. Microbes are an unseen part of nature, and an essential part of the biodiversity that sustains life. Thus, we wondered about the relationship between biophilia and the hygiene hypothesis.
Biologist Edward O. Wilson proposed biophilia as rich, natural pleasure derived from being surrounded by living organisms, including a diversity of plants and animals. The focus was on visible forms of life. The hygiene hypothesis (and its variants) suggests global elevations in non-communicable diseases could be related to diminished early-life opportunity exposure to a diversity of microbes via sanitization and modernity.
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Dysbiosis means life in distress/difficult living. It can describe unhealthy shifts in microbes residing on the skin, in the gut or other locations. Dysbiosis in the microbial sense is environmentally driven. We wondered if humans might actually subconsciously receive natural pleasure — via immune responses — with help from diverse groups of microorganisms encountered in natural environments.
We had reason for such outlandish thoughts. Independently, our respective research had examined the hygiene hypothesis, explaining the protective potential of microbes in early life, and provided a contemporary framework for microbial influences on fatigue, cognition and depression. Microbes encountered in nature have been directly and indirectly influencing the immune system of our genus for nearly three million years.
We also discussed shinrin-yoku (Japanese term for forest bathing, or taking in the forest air). Throughout the 1990s, Japanese researchers examined forest-based exercise in patients with diabetes. They also reported improved mood and lower stress hormone production when healthy adults walked in forests as opposed to indoor treadmills.
Shinrin-yoku places emphasis on breathing — the intake of airborne aromatic chemicals and other unseen elements emitted from trees and forest floors. It involves mindfulness, present-moment awareness and "absorbing" nature through all senses. There was much to encounter beyond the visual while walking in woodland.
Mindfulness involves orientation to experience. That is, being oriented to the present moment with curiosity, openness and acceptance. Examples include listening to the sounds of birds or ripples of water, examining details in leaves, feeling tree-bark texture, letting soil aromas hit the nasal passages...as if it were the first time.
What were we breathing in as we walked in nature? How does air within vegetation-rich areas differ from air in a built environment? Is built-environment air simply filled with human-generated particulate matter, or is it absent of therapeutic substances secreted from trees? Were inhaled microbes different, too? What about personal orientation to nature? Recently we have explored these questions.
More than a dozen years on from our bus ride, scientists have published volumes of research on natural environments and biodiversity for human health. Research on shinrin-yoku has shifted to more accessible urban and semi-urban forests. Scientists report lowered stress hormones, decreased markers of inflammation, improved immune functioning and positive mental outlook after walks in green space compared to built environments.
Mindfulness can bridge the gap between the inherent value of natural environments and maximizing potential for individual well-being. Personal nature relatedness — an individual's fascination with and desire for nature contact — is associated with mental well-being. Mindfulness and the ability to perceive and engage with natural beauty are linked to nature relatedness.
Microbes in the air and soils of natural environments can be unique. Microbial differences on the skin of those living in close proximity to more diverse vegetation may directly influence immune function throughout the body and may even influence mood. Indirectly, microbes help manufacture the airborne phytonides — natural chemicals secreted from trees — that are linked to healthy immune functioning.
Researchers continue to uncover the mechanisms behind the therapeutic value of nature and the products of biodiversity. Benefits are not exclusive to remote wilderness. Local nature and backyard biodiversity are often within easy reach, and they can provide ample benefit. We have much to learn, and in the meantime, the outdoors beckons.
The David Suzuki Foundation is once again challenging Canadians to get outside into nature for 30 minutes daily during May. The benefits of engagement are many. Elizabeth Nisbet, co-developer of the Nature Relatedness Scale, has found that 30×30 participants double their usual time in contact with nature, and experience reduced stress and improvement in mood and vitality.
Participants of 30×30 experience greater connectedness to nature, which links to improvements in personal well-being. A British study involving a 30-day engagement with nature program reports similar findings. Engagement brings sustained increases in happiness, health, connection to nature and pro-environmental behaviours.
The results demonstrate that 30×30 is a win-win-win for personal, community and planetary health. Connecting with local biodiversity illuminates the connectivity of all life, and the importance of equitable access to nature as a fundamental right. Consideration of mindfulness during 30×30 might provide an "extra strength" dose of personal vitality.
Susan Prescott is a professor in the School of Paediatrics and Child Health Research at the University of Western Australia. She has published over 250 peer-reviewed articles, and several books, including Origins: Early-life Solutions to the Modern Health Crisis (UWA Publishing, 2015). Alan Logan is an independent researcher, contributor to Harvard School of Public Health's Natural Environments Initiative and co-author of Your Brain on Nature (Harper, 2012).