Forest bathing really is good for your health

Forest bathing or Shinrin-yoku - spending time in a forest or other green space to reap health benefits - has become an increasingly popular activity in recent years, especially in countries like Japan, where it’s taken very seriously.

But forest bathing isn’t a new-age healing fad; it’s an increasingly well-evidenced health habit that’s gathered a lot of popular and scientific interest in the last few years.

A recent meta-analysis from the University of East Anglia, published in the journal Environmental Research, found that people who spend more time in green spaces have significantly reduced risks for a number of chronic illnesses.

According to the paper, people have been aware of the connection between greenery and health since the 19th century, which in part is why city parks and green spaces were developed so thoroughly in that period, especially in industrial cities such as London, Leeds and Glasgow.

The research looked back at data from 103 observational studies and 40 interventional studies, tracking 290 million participants, from 20 different countries, and correlating the amount of time people spent in green spaces with 100 health outcomes over time.

Spending more time in green spaces was linked to reduced levels of the stress hormone cortisol, lower heart rate, reduced risk of coronary heart disease, lower blood pressure, lower cholesterol, reduced risk of type II diabetes, reduced all-cause mortality and death from heart disease. Some of the studies even suggested a possible link between green spaces and cancer outcomes, neurological outcomes, sleep duration, and certain biomarkers, though more research is needed.

A number of possible explanations exist, including the obvious - green spaces promote physical activity, social interaction, exposure to sunlight, reduced pollution and better air quality,, all of which boost health in various ways.

But there’s also another possibility - phytoncides.

Phytoncides are volatile organic compounds (VOCs) given off by trees - airborne organic compounds with antibacterial and antifungal properties that protect trees and plants from germs and parasites.

When we breathe in these compounds as we walk or run through green spaces, our bodies respond in a number of ways. There are thousands of phytoncides, but the most common forest-related compounds such as β-pinene, β-myrcene, camphene and α-pinene have antioxidant, anti-inflammatory and anti-depressive properties, which can help to improve mood, promote relaxation, aid sleep and even reduce blood glucose levels.

A clinical trial conducted in South Korea, for example, found that a group of people walking for one hour in a forest a normal pace “significantly decreased systolic and diastolic blood pressure, reduced arterial stiffness and significantly increased lung capacity” when compared to a control group walking at the same pace and time in the city.

Phytoncides also increase the number and activity of a type of white blood cell called natural killer cells or NK, which kill tumour- and virus-infected cells in our bodies. In one recent Japanese study, increased NK activity from a 3-day, 2-night trip to a forest lasted for more than 30 days. 

So the lesson here - getting out into nature, for a walk or a run, really does do you good.