The Japanese have been studying the health benefits of Shinrin-yoku for nearly 20 years. Shinrin means forest and yoku means bath so the best English translation is Forest Bathing. There is no need to get wet when we bathe in the forest but we do need to relax and soak up the atmosphere.
A gentle stroll through the forest, allowing ourselves to absorb the peace, the sounds, the sights and the smells has been shown to have huge health benefits. So much so, that the practice is now promoted by the Japanese Government and several countries are now developing organisations and programmes to encourage ‘ Forest Medicine’.
We instinctively know that a walk in the park, or a hike in bush is relaxing and makes us feel better but there is actually a considerable body of clinical research to confirm the health benefits of forest bathing.
Trials have shown decreased levels of the stress hormones adrenalin and noradrenalin, increased parasympathetic nervous activity and decreased sympathetic activity in those walking in the forest. These physiological changes translate to a reduction in blood pressure and heart rate and huge psychological changes with decreased levels of anxiety, depression, anger and fatigue aligned with Increased levels of vigour.
Now, these alone are fabulous outcomes but that is not the end of it.
It appears that Forest walking may actually be able to help us fight the coronavirus that is currently causing devastation throughout the world.
When our bodies are challenged by the SARs-CoV-2 virus we rely on our immune system to respond and to destroy the invader. We depend specifically on our innate immune system and one of the big players in innate immunity is the Natural Killer cell (NK).
For our innate immune system to function well we need plenty of highly active NK cells and they need to be rich in a several enzymatic proteins necessary to destroy the virus. These include Granulysin, Perforin and Granzymes A and B.
The research shows that just one 2 hour walk in the forest can activate NK cells and their enzymes and three 2 hour walks over two days increased activity by around 50% in more than 90% of participants.
To add to the excitement the increased NK activity consistently lasts for 7 days and possibly even as long as 30 days after the walks are completed.
A series of studies have suggested that the increased NK activity is probably stimulated by inhaling aromatic chemicals released by the trees themselves. These Phytoncides, such as alpha-pinene, tricyclene and camphene are abundant in the forest air and inhaling these volatile oils appears to stimulate NK activity, they increase NK cell numbers and elevate the levels of their essential enzymes.
Walking for 2 hours in the city certainly does have health benefits but it does not expose us to Phytoncides. Researchers have confirmed that city walks do not induce the same NK cell changes, you do need to be in the forest and you do need the aromatic oils.
So what can we learn from this research?
Firstly, forest bathing has a number of great health benefits including stimulating our immune system and potentially increasing our resistance to viral infection.
Secondly, the benefits of exposure to the forest air can last at least a week and possibly even a month. You don’t have to do it all that often.
Finally the research does raise a few rather confronting questions. Is it possible that city dwellers are at increased risk from COVID because of their reduced contact with natural forests? And will our social isolation policies actually reduce the ability of our immune systems to counter the challenge from the corona virus?
We certainly cannot answer these questions with any certainty at present but perhaps it would be worth finding a little time to walk in your nearest forest or national park. Get out into your natural environment and partake in a little of your own forest bathing.