A belief that nature is good for you may sound like common sense, but in Japan, researchers have taken the idea to the laboratory and produced evidence that a walk in the woods could help prevent cancer, fight obesity and reduce stress and depression.

The Japanese have coined the term “shinrin-yoku”, or forest bathing, to codify the practice of exposing yourself to nature (particularly trees). The government has invested millions in both research and “forest therapy trails” – there are now 60 of them in Japan- where the forests have sufficient density and trails are of sufficient length to provide the benefits of foresting bathing.

The concept is to take a “bath” in the forest by letting nature enter all five senses. Qing Li, associate professor at Tokyo’s Nippon Medical School and president of the Japanese Society of Forest Medicine, argues that the sense of smell is most important.

“The effect of forest bathing is the total effect, but the biggest effect is from the olfactory, smell, we call them phytoncides. Also, people call them essential oil, aroma.” Li’s research has shown that trees’ aromas, known as phytoncides, boost our body’s NK (natural killer) cells which help fight tumors and virus-infected cells. Phytoncides are the medical equivalent of essential oils; the most effective aroma is Japanese Cypress.

(Qing Li is editor of “Forest Medicine“, an English-language textbook)