Yesterday, we met up with my wife’s family for a long walk in a forest not far from her family home: Five dogs, seven people, and thousands of trees. And the deeper into the forest we went, the better we all felt. It was visible and predictable. It happens every time and to everyone. But why?
Eleven years ago, some Japanese scientists published a study on the “effect of phytoncide from trees on human natural killer cell function”. They concluded that exposure to these phytoncides (or aromatic volatile substances) and the decreased stress hormone levels “may partially contribute to increased NK activity”, i.e. human natural killer cells and that the “increased NK activity lasted for more than 7 days after trips to forests both in male and female subjects”.
Incredible. And even if the study’s conclusions are incorrect about these phytoncides, few people (apart from Blair Witch fans perhaps) would disagree with the calming effect of forest walks.