Frank Lloyd Wright said, “Study nature, love nature, stay close to nature. It will never fail you.” The iconic architect, known for his organic designs that make his buildings a bridge to nature, might have hit the nail right on the head. Most of us will agree that taking a nature walk is healthy and deeply relaxing. But even beyond personal experiences and intuitions, research has accumulated convincing evidence that (recurrent) contacts with nature indeed lead to (long-term) positive health outcomes.^[i] The range of beneficial psychological and physiological health outcomes is amazing, to say the very least. These benefits include but are not limited to helping against depression, anxiety, ADHD but also infections, cancer, and cardiovascular diseases. Not to mention the overall stress reduction and the increase in focus and mood that people experience after a nature walk.

As to why these benefits are present, the jury is still out. There are various theories, ranging from positive payoffs from an evolutionary ingrained connectedness with nature (the biophilia hypothesis^[ii]) to purely biological effects that come from inhaling volatile compounds released by trees and plants into the air, for example phytoncides. Especially forests seem to be real treasure troves of these organic compounds, thought to benefit plants and trees by protecting against bacteria, insects and fungi or serving self-repair.^[iii] Whatever purpose they serve, when taking a deep breath of forest air, you smell them: the typical woodsy fragrance, or the smell of nature after it has rained.

Human centrists might argue that if all the benefits indeed come from chemicals, we should just put them in pills or air fresheners. After all, they argue that nature’s resources can be justifiably exploited for our benefit. However, they are missing the larger picture that appears to be emerging from research. Professor Ming Kuo at the University of Illinois believes that not only the phytoncides contribute to our health, but that it is a combination of effects, for example also from the cleaner air, or from the exercise and social contacts you get from walking in nature with friends. Try putting that in a pill. A large part of the positive health effects could be explained from positive effects to the human immune system.¹ Phytoncides, together with the physical exercise and with positive effects coming from micro-organisms like Mycobacterium vaccae, readily found in forest soil, boost the immune functioning, and even generate anti-cancer proteins.^[iv]

More and more countries make nature-based initiatives or forest walks part of their official health policy. In Japan, shinrin-yoku (forest bathing), already introduced in 1982, advises citizens to take forest walks.^[v] The Institute for European Environmental Policy recognized that nature provides solutions to today’s health challenges and that inclusive access to nature plays an important role in this.^[vi] It would not be an unrealistic prediction that nature-as-medicine could become mainstream. So, there seems no doubt about nature’s positive effects. However, to benefit from these, nature needs to be conserved and the rapid decline of our natural environment needs to be stopped. Creating more awareness about these benefits could give a boost in that direction. To be more ambitious, however, we should follow Frank Lloyd Wright’s philosophy: integrate nature in our homes and let green cities be the bridge between our modern comfort and the proven benefits of living in and as part of nature.  An argument sometimes used to convince people of saving the rainforest is that it is full of yet-to-be-discovered medicines. But maybe those medicines are already right under our noses. Nature, before anything else, was Wright’s most inspiring force, and maybe all of us should take the same stance.  Perhaps by saving the forests we are also saving ourselves.

^[i] Kuo, M. (2015). How might contact with nature promote human health? Promising mechanisms and a possible central pathway. Frontiers in Psychology, 6. https://doi.org/10.3389/fpsyg.2015.01093.

^[ii] Ulrich, R. (1993). Biophilia, biophobia, and natural landscapes. Biophilia, Biophobia, and Natural Landscapes, 7, 73–137.

^[iii] Lee, J., Cho, K. S., Jeon, Y., Kim, J. B., Lim, Y., Lee, K., & Lee, I.-S. (2017). Characteristics and distribution of terpenes in South Korean forests. Journal of Ecology and Environment, 41(1), 1–10. https://doi.org/10.1186/s41610-017-0038-z.

^[iv] Li, Q., Kobayashi, M., Wakayama, Y., Inagaki, H., Katsumata, M., Hirata, Y., Hirata, K., Shimizu, T., Kawada, T., Park, B. J., Ohira, T., Kagawa, T., & Miyazaki, Y. (2009). Effect of phytoncide from trees on human natural killer cell function. International Journal of Immunopathology and Pharmacology, 22(4), 951–959. https://doi.org/10.1177/039463200902200410.

^[v] Hansen, M. M., Jones, R., & Tocchini, K. (2017). Shinrin-yoku (forest bathing) and nature therapy: A state-of-the-art review. International Journal of Environmental Research and Public Health, 14(8). http://dx.doi.org/10.3390/ijerph14080851.

^[vi] ten Brink, P., Mutafoglu, K., Schweitzer, J.-P., Kettunen, M., Twigger-Ross, C., Baker, J., Kuipers, Y., Emonts, M., Tyrväinen, L., Hujala, T., & Ojala, A. (2016). The health and social benefits of nature and biodiversity protection. A Report for the European Commission (ENV. B. 3/ETU/2014/0039). London/Brussels: Institute for European Environmental Policy, p. 243.