"Nature doesn’t bang any drums when she bursts forth into flowers, nor play any dirges when the trees let go of their leaves in the fall. But when we approach her in the right spirit, she has many secrets to share. If you haven’t heard nature whispering to you lately, now is a good time to give her the opportunity.”

~ Osho, in Osho Zen Taro: the Transcendental Game of Zen
 

As we all innately know, spending time in nature is good for our body, mind and spirit. It’s why we’re attracted to green places, flowers, lakes, fresh air and sunshine. Taking a nature walk—affording plenty of fresh air and exercise in a quiet setting—has traditionally been prescribed for good health. That raises a question: How much natural healing are we sacrificing when we spend most of our days indoors?

In Japan, a group of medical researchers and government-affiliated forest organizations support the creation of forest therapy centers, where people enjoy the trails and guided walks and also receive free medical checkups under the trees. Since 1984, they have been studying the health benefits of walking in the woods, termed shinrin-yoku, or forest bathing. There are now more than 30 such officially designated sites.

In related studies, scientists from Japan’s Nippon Medical School and Chiba University tracked positive physiological changes in individuals walking in the woods compared with city walkers. Early results were published in the International Journal of Immunopathology and Pharmacology, European Journal of Applied Physiology and Journal of Biological Regulators and Homeostatic Agents. Forest walkers showed:

• Lower concentrations of salivary cortisol, known as the stress hormone
• Lower blood pressure and heart rate
• Reduction of adrenaline and noradrenalin, also stress-related hormones
• Increase in immunity-boosting natural killer (NK) cell activity, and the numbers of NK cells and anti-cancer proteins known to combat cancer

Newest Findings

The researchers theorized that organic compounds called phytoncides, produced by trees and other plants as a protection from disease, insects and fungus, were also producing beneficial natural killer cells in people in the forests. In a study that exposed participants to phytoncides via aromatic oils fed through a humidifier in a hotel room, the researchers found similar increases in NK levels.

A 2011 study by Nippon Medical School’s department of hygiene and public health showed that the resulting increase in NK cells lasted for 30 days. They concluded that a monthly walk in the woods could help people maintain a higher level of protective NK activity and perhaps even have a preventive effect on cancer generation and progression.

Qing Li, Ph.D., the assistant professor leading several of these studies, suggests that dense forest areas are more effective at boosting immunity than city parks and gardens. He also reports that phytoncide concentrations increase during summer growing seasons and decrease during the winter, although they are still present in tree trunks even when the trees are deciduous.

Li further suggests that walks in the woods should be conducted at a leisurely pace. For stress reduction, he suggests four hours of walking, covering a generous 3 miles, or 2 hours walking about 1.5 miles. For cancer-protecting effects, he suggests regularly spending three days and two nights in a forested area.

“Carry water and drink when you’re thirsty,” says Li. “Find a place that pleases you and sit and enjoy the scenery.” He adds that relaxing in a hot tub or spa counts as a perfect end to a day of forest bathing.

Li foresees a future in which patients diagnosed with high blood pressure or hypertension may receive a forest bathing prescription, but counsels that shinrin-yoku is considered preventive, rather than therapeutic, medicine.

Enhancing Nature’s Power

Ecopsychologist Michael Cohen, Ph.D., executive director of Project NatureConnect, adds, “If you want to increase the healing effect of being in nature, it helps to change the way you think and feel about connecting with it.” He has students repeat the word ‘unity’ as they encounter natural attractions—be it a tree, bird, brook or breeze—until they feel that they are part of nature, not separate… part of the healing wisdom of the planet. More, he states, “Sharing helps solidify the experience and opens you to greater personal healing.”

Maggie Spilner, author of Prevention’s Complete Book of Walking and Walk Your Way Through Menopause, leads walking vacations for her company, Walk For All Seasons.