What is Nature-Based Medicine and What Does It Do?

Abstract

One’s personal health and well-being can improve with activity in natural environments or decline without it. Many chronic illnesses to which personal nature deficiency contributes—including anxiety, depression, attention deficit, diabetes, hypertension, myopia, and obesity—have been exacerbated with the pandemic. That those illnesses may be preventable, treatable, and even reversible with an added nature-based approach may seem novel, but it is not. Though the field of nature-based medicine is just emerging in the U.S., it has been taught and practiced in Asia and the EU for decades. As the prescriptive, evidence-based use of natural settings and nature-based interventions, it aims to prevent and treat disease and improve well-being. Nature-based medicine blends particular activity in nature with the science of medicine to attempt to empower self-care safely, effectively, and happily. Its vision is to be readily available to all, regardless of proximity to blue (water-related) or green (land-related) space. The common sense of nature-based medicine belies its scientific evidence base, which is growing but not well-known, so it may seem unfamiliar to prescribe nature to patients. It will take education, training and practice to help patients access nature-based medicine and to help clinicians prescribe it.

“The more exposure to and experience with the potentially preventive and therapeutic aspects of nature patients have, the more they may benefit directly.”

Learning survivalism and experiencing the awe of a sunset are not currently considered clinical therapies. But wilderness—and nature itself—offer therapeutic tools wildly beyond the 80% of prescription pharmaceuticals which are derived from plants. In this issue, Moore ¹ begins to identify the published scientific evidence suggesting that wilderness activity can be clinically helpful to patients.

Moore’s work shows the new enthusiasm that has emerged for exploring how one’s personal health and well-being can improve as a result of activity in natural environments. This surge in interest in self-care and our surroundings results in part from the Covid pandemic. Early on, governmental authorities encouraged people to stay indoors, despite the data showing that few cases of Covid were transmitted while outdoors. As a result, our pre-existing collective nature deficiency ² worsened. The chronic illnesses to which nature deficiency contributes—including anxiety, depression, attention deficit, diabetes, hypertension, myopia, and obesity—all have worsened.

Those very illnesses, however, are preventable, can be treatable and may even be reversible with an added nature-based approach. Like culinary medicine, ² nature-based medicine can be a tool in a clinician’s toolkit, and offer patients and clinicians an accessible, adjunctive approach to healing. Nature itself, as Moore mentions, is not necessarily remote, fearsome, or bad, like we see on TV. It can be the breeze ruffling your curtains, the dog at your feet, the salad in your lunch, the plants on your windowsill.

A new field, nature-based medicine is defined as the prescriptive, evidence-based use of natural settings and nature-based interventions. Its mission is to prevent and treat disease and improve well-being. Nature-based medicine blends particular activity in nature with the science of medicine to attempt to empower patient self-care safely, effectively, and happily. Its vision is to be readily available to every family, regardless of proximity to blue (water-related) or green (land-related) space.

The common sense of nature-based medicine is a smokescreen for the science behind it. Though there are few peer-reviewed publications, grant monies, books, or biomedical journals entitled “Nature-Based Medicine,” its scientific evidence base is growing but not well known. Moore helpfully illustrates that evidence base for wilderness; here are other intriguing findings for nature-based interventions.

Bright light therapy may be as effective ³ as Prozac for seasonal affective disorder; a deliberate park walk may be as effective ⁴ as Ritalin for childhood ADHD; aerobic exercise may be as effective ⁵ as oral anti-depressants for major depression; 120 minutes of free play may stabilize and sometimes reverse ⁶ childhood myopia; those with greater nature exposure had fewer episodes of depression and anxiety during Covid. ⁷ Walking in a forest for 30 minutes may drop blood sugar ⁸ 40% after 30 minutes in diabetics; in this study, the same blood sugar drop while indoor cycling took 3 hours. Hospitalized patients who have plants in their rooms ⁹ may have less fatigue, anxiety, and pain, shorter hospitalizations and higher hospital and room satisfaction than those without them.

Nature-based interventions have also been identified as promising preventive tools.

Spending time in a forest exposed to an evergreen’s phytoncides enhances natural killer cell activity ¹⁰ and lowers blood pressure and interleukin-6 activity.

Volitional nature activity 120 minutes weekly appears to lower cortisol levels 21% beyond diurnal variation. ¹¹

Gardening daily may reduce risk factors for dementia ¹² by 36%.

Patients with dementia and access to enriched, stimulatory gardens are less likely to fall ¹³ or suffer loss of an activity of daily living than those without such access.

Quality greenspace exposure may improve cognition. ¹⁴

Greater soil biodiversity appears to act as a barrier to antibiotic resistance. ¹⁵

Nature-related activities improve the gut microbiota and fecal serotonin of preschool children, and result in less stress and anger. ¹⁶

Indoor greenwalls ¹⁷ improve skin microbiota and immune regulation among urban office workers.

Medical schools in Japan, South Korea, Denmark, the Netherlands, and the UK have all offered medical education in elements of nature-based medicine for decades. In Tokyo’s Nippon Medical School, forest therapy was first identified and described, in 1982. New Zealand physicians have written green prescriptions since 1998; Scottish physicians have been authorized to prescribe nature to their patients since 2018, and Canadian physicians since 2020.

The first U.S. medical school Center for Nature and Health was established in 2016 at UC San Francisco; the first medical residency elective in regenerative agriculture in a US medical school opened in 2021; the first medical student lecture in the field was given at Harvard Medical School in 2021; at least five US medical schools teach nature-based medicine to undergraduates as elective courses. The first nature-based medicine digital Continuing Medical Education (CME) credits were offered in 2020 by Park Rx America. Several health care systems now offer nature-based medicine programs to clinicians and the public, including therapeutic horticulture, guided forest bathing, simple green exercise, and surf, equine, and horticultural therapy.

How does nature work? Moore cites biophilia, attention restoration and stress reduction as leading theories about how wilderness improves human health. Kuo ¹⁸ has identified 20 somewhat more granular mechanisms underlying nature-based interventions; she concludes that enhanced type 1 immunity is a primary mechanism. But the issue has just begun to be explored: why an outdoor activity of choice improves stress and lowers cortisol; why there is a reduced need for anti-depressants in densely green and blue urban areas; and why gardening in soil favorably changes gut microbiota are unanswered mechanistic questions.

Introducing a particular nature-based activity as a clinical suggestion is new for most clinicians. Asking a patient “Have you been outside deliberately for yourself today?” and “Are there indoor plants nearby at work or home?” offers an easy lead-in to discussion of the benefits of an outdoor green or blue activity.

One format for nature-based medicine prescriptions is just as a medication. Location name, and description, duration and frequency. For example write: simple sitting in a specific garden, 30 minutes daily, three times weekly. Gauging symptoms if any, on a 1–10 scale, and any self-assessed medical parameters such as blood pressure and pulse, before and after the activity can help its evaluate effectiveness. This format is simple and patterned after how clinicians prescribe medication.

Note that simply suggesting “walking outside and getting some fresh air” is not specific enough to be helpful. A nature-based approach can and should be tailored medical advice.

In fact, literally walking the talk may be one of the most powerful therapies a clinician can offer, and some clinicians go for walks with their patients. For example, the Walk with a Doc organization models this. The clinical effect of the “hidden curriculum” (how clinicians themselves behave) is underestimated. Examples include personally exercising outside, displaying posters of nature in the office or hospital, or having or featuring pets or plants in the medical office. Each shows personal commitment and an evidence-based approach to well-being.

Still, it may not be easy to prescribe nature to patients, even with personal examples and enthusiasm like Moore’s. Barriers to nature-based therapy exist, including patient physical limitations, traditional expectations for a pharmaceutical solution to problems, the availability of transportation to a desired green or blue space, and the physical safety of one’s surroundings. Socioeconomic and racial barriers to green and blue spaces can block access to BIPOC people and others. ¹⁹ Different natural environments are pleasurable and fearsome to different people. Few physicians have been trained to facilitate patient access to better self-care skills and to community-based programs.

Happily, occupational, recreational, and rehabilitative medicine specialists already have specialized training to offer condition-specific advice. More curricular and training opportunities will be needed. Other expert non clinicians, including local farmers, landscape architects, master gardeners, forest rangers, and guides have much to offer nature-based medicine as well.

Future Challenges

As nature-based outdoor interventions are not always available or possible, indoor interventions may be substitute for them and indeed be preferable in some circumstances. Biophilic virtual reality (VR) has been shown to reduce stress. Nature-based augmented and VR researchers has shown efficacy in reducing fear and pain in surgical procedures and pain modulation. ²⁰ Bringing the outside in includes green walls, house and office plants, animal-assisted therapy, and aromatherapy.

Funding for exploring nature-based interventions will need discussion. In the not-too-distant future,

An insurer-paid app might direct you to a local forest, park, or meadow, or offer you an effective anti-anxiety nature dose.

A workplace wellness program might pay for your office greenwall to reduce absenteeism or increase presenteeism.

An insurer might offer you a discount for time deliberately spent outside or in a home or office sited in a green, high air-quality area.

A formulary might list a care farm stay, as is common in the Netherlands and the UK, and provide stroke or PTSD rehabilitative time.

Indoor air and water filtration systems might be available to those sensitive to pollutants.

Nature-based digital therapeutic interventions for anxiety, seasonal affective disorder and other conditions might be FDA-approved and utilized even more widely.

Many important clinical questions are still unanswered. Are specific activities and time spent in nature more effective when prescribed by a clinician than when undertaken on one’s own? What medical differences and opportunities exist for the disadvantaged, including those with historically limited or inequitable access to nature? Are there model medical school curricula for students which can be shared at nominal cost, as culinary medicine has done?

Conclusion

The power and promise of wilderness as a prescription is part of nature-based medicine. The field is something to embrace and build, and share with patients who need it. The more exposure to and experience with the potentially preventive and therapeutic aspects of nature patients have, the more they may benefit directly. Whether clinicians will be able to undertake adequate additional education and training in nature-based medicine, access evidence-based materials and research, practice the skills required to meet patient needs, ascertain ways to help people disadvantaged by the social determinants of health and be appropriately compensated for their efforts is unknown, and defines the core challenges ahead.