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An Interview with Forest Medicine and Shinrin Yoku Researcher Dr. Qing Li

Dr. Qing Li at the birthplace of forest bathing (Photo provided by Q. Li)

I recently had the opportunity to interview Qing Li, MD, PhD, Associate Professor at Nippon Medical School in Tokyo, Japan. Dr. Li has been at the forefront of forest medicine research on the practice of shinrin yoku (forest bathing), which is walking in the forest to obtain the health benefits. Dr. Li is also the Vice-President and Secretary General of the International Society of Nature and Forest Medicine based in Japan. I have been collaborating with Dr. Li in hopes of establishing this organization in North America.

Dr. Li was also recently interviewed for a program on BBC Radio called ‘The Secret Power of Trees’ which will be broadcast on Saturday, December 8, 2012 at 10:30 a.m. UK time.  Outside Magazine recently published an article in its December 2012 issue on “The Nature Cure” which also features Dr. Li’s research.

Hiking Research: Why are you interested in forest medicine? How did you become involved in this type of research?

Big cedar forest in Japan (Photo provided by Q. Li)

Dr. Qing Li: In 1982, the Forest Agency of Japan first proposed a new movement called “forest bathing trip” as a healthy lifestyle. Now it has become a recognized relaxation and/or stress management activity in Japan. However, there has not been sufficient medical evidence supporting the therapeutic effects of forest bathing trips and evidence-based evaluation as well as a therapeutic menu of forest bathing trip have been requested. Against this background, the Ministry of Agriculture, Forestry and Fisheries of Japan initiated a research project between 2004 and 2006 to investigate the therapeutic effects of forests on human health from a scientific perspective.

In fact, my major is Environmental Medicine, especially in the field of Environmental Immunology. I have been studying the effects of environmental chemicals, stress and lifestyle on immune function since 1988. I am interested in the effect of all environmental factors on human health. I am also interested in the effect of forest environments on human health.

Because of my background, when the Ministry of Agriculture, Forestry and Fisheries of Japan organized the project team, I was invited as a main member of the project team.

Hiking Research: Has forest medicine been accepted by “traditional” medicine practitioners in Japan as a treatment for health issues?

Forest bathing in a Japanese Cypress forest (Photo provided by Q. Li)

Dr. Qing Li:  The Forest Medicine has been accepted by “traditional” medicine practitioners in Japan as a preventive medicine for health issues, but not as a treatment for health issues.

Hiking Research: Do organizations in Japan provide employees paid time to experience nature?

Dr. Qing Li: Some companies in Japan hold study and training meetings for new employees in Forest Therapy bases. Some companies make a contract with Forest Therapy bases for providing employees time to experience nature.

Hiking Research: What are your suggestions for optimizing a forest bathing experience to obtain the greatest benefits?

Dr. Qing Li: Usually I suggest working men and women take a two-night/three-day trip to forests for obtaining the better benefits. Because one day trip is too short and more than three day trip is too long. However, a longer trip will be better for senior citizens.

Hiking Research: How much forest area is needed to obtain these benefits? Do certain types of trees offer more benefits?

Dr. Qing Li: In Japan, forest is used to refer to land with a tree canopy cover of more than 30 percent and area of more than 0.3 ha. The trees should be able to reach a minimum height of 5 m with a width of more than 20 m. The forests including Japanese cypress (Chamaecyparis obtuse, Hinoki in Japanese), Japanese cedar (Cryptomeria, Sugi in Japanese) have shown beneficial effects.

A group of women enjoy forest bathing (Photo provided by Q. Li)

Hiking Research: Japan has designated Forest Therapy Bases. How are forests validated? Who does this?

Dr. Qing Li:  Japan has designated 48 Forest Therapy Bases so far. (

The forests were validated from the following aspects: 

  1. Physical factors: air temperature, humidity, illuminance, radiant heat, air current (wind velocity), sounds (the sound of a waterfall, the whispering of the wind in the trees), and so on.

  2. Chemical factors: volatile organic compounds derived from plants (trees), such as alpha-pinene and limonene, which are terpenes including hemiterpenes, monoterpenes, sesquiterpenes, and diterpenes, also called phytoncides.

  3. Psychological factors: those factors reflecting the subjective evaluation of forest environments such as hot/cold, light/dark, tense/relaxed, beautiful/ugly, good/bad, relaxing/stimulating, quiet/noisy, and plain/colorful. Semantic Differential (SD) is usually used to evaluate the psychological responses to forest environments. The technique was originally developed to measure affective responses to stimulus words and concepts in terms of ratings of bipolar scales defined with adjectives on each end. The SD methodology is considered a simple, economical means of obtaining data on emotional reactions that could be used in many different situations or cultural contexts.

  4. Physiological effects: Data/evidence obtained from experimental studies including field investigations and laboratory experiments, .i.e., investigations on the effect of walking in forests and natural environments on psycho-neuro-endocrino-immunology. These experiments study the effect of forest environments on the central nervous system (prefrontal cerebral activity, functional MRI), the sympathetic and parasympathetic nervous systems (blood pressure, heart rate variability), psychological responses (the POMS test), the endocrine system (stress hormones such as cortisol and adrenaline), and the immune system (NK activity, intracellular anti-cancer proteins in NK cells) determined by physiological, biological, biochemical, psychological, and immunological methods. Recent technological developments have enabled us to conduct the above investigations in a forest field.

A research team evaluates the forests and a Committee designates the Forest Therapy Bases based on the results obtained by the research team.

Hiking Research:  Can forest therapy bases be started in other countries? What is the process?

Dr. Qing Li: Yes. Recently South Korea has started to designate Forest Therapy Bases based on the experience in Japan. (The steps to establish Forest Therapy Bases are listed in the previous question.)

Hiking Research: Describe the connection Japanese citizens have with the natural environment. How active are they in visiting the forest therapy bases to experience the benefits of shinrin yoku?

Dr. Qing Li: Walking in forests has now become a well-recognized relaxation and/or stress management activity in Japan. Many people in Japan visit the forest therapy bases to enjoy the forest bathing trip and to experience the benefits of shinrin yoku during weekends and holidays. I also visit forest parks during weekends and holidays.

Hiking Research: What research projects are you currently involved with?

Dr. Qing Li: I am doing a project on the preventive effect of forest walking on life-style related disease. In my university (Nippon Medical School), I have a special program of Forest Medicine for medical students. In this program, eight to thirteen medical students visit city green parks in Tokyo every Monday afternoon for about 2 hours during April to November to enjoy the effect of forest bathing. The students take questionnaires before and after the walking to evaluate the psychologically calming effect. This program started from 2009.

Hiking Research: What do you see as emerging trends in nature and forest medicine?

Dr. Qing Li: Imagine a new medical science that could let you know how to be more active, more relaxed and healthier with reduced stress and reduced risk of lifestyle-related disease and cancer by visiting forests. This new medical science is Forest Medicine.

Forest Medicine has emerged as a new interdisciplinary science and a focus of public attention. Forest Medicine belongs to the categories of alternative medicine, environmental medicine and preventive medicine and is the study of the effects of forest environments on human health.

Nature and Forest Medicine will prevent people from cancers and lifestyle-related diseases such as heart disease, diabetes, cerebrovascular disease, depression and hypertension.

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