Take A Forest Bath For Your Health
- The Little Physio
- Jun 7, 2019
- 4 min read
Have you ever gone for a walk in your local nature reserve or around lush greenery and felt more calm, relaxed and overall better? It looks like there is evidence to suggest there are psychological and physiological benefits to reap from being in nature, such as, participating in forest bathing.
Forest bathing, or shinrin-roku, is a traditional Japanese practice characterised by walking in a forest environment, watching the surroundings and breathing. It’s an altogether sensory experience in a forest and is considered an art and a type of meditation.
Benefits of forest bathing
The benefits of forest bathing can be found within the cardiovascular system, immune system and wellbeing. Some of the positive effects of forest bathing is hypothesised to be mediated by the volatile organic compounds emitted by trees. The compound is known as phytoncide, also known as essential oils from trees.
Immune system
In a three day (two nights) forest bathing trip study (Li et al. 2008), a group of participants were asked to walk in the forest for 2 hours per day, sometimes twice per day. Pre- and post-forest bathing measurements were taken to assess natural killer cell activity and sympathetic nervous system activation through concentrations of adrenaline and noradrenaline.
The forest walkers had increased natural killer cells and an increase in their activity measured by an increase in perforin, granzymes A/B and granulysin. Natural killer cells are subtype of immune cell with important functions in protecting the body from developing cancer cells. They are able to recognise and promote the death of cells with cancerous activity. Furthermore, there was a decrease in both adrenaline and noradrenaline concentrations, suggesting a decrease in sympathetic output or a decrease in the ‘fight or flight’ stress response. This increase also lasted for at least 7 days and returned to baseline by 30 days. These changes were not see in those who completed walks through an urban environment.
These results suggest forest bathing alone can have positive effects on promoting immune function and reducing stress, which may have preventative benefits for cancer development and stress-related diseases.
Cardiovascular measures and cortisol
Another study has looked at the effect of forest bathing on cardiovascular function markers. Pulse rate, blood pressure and heart rate variability were measured pre- and post-treatment in forest walkers who also walked in cities. They were also measured after just viewing the environment (e.g. taking in the landscape) and after walking.
In only the forest walk, was there a decrease in pulse rate and blood pressure on both the diastole and systole. Again suggesting a decrease in sympathetic drive and an increase in parasympathetic activity, the ‘rest and digest’ response. Additionally, salivary cortisol was also measured. In line with the positive effects on the cardiovascular system, salivary cortisol levels decreased after both viewing and walking. Cortisol, is a common marker of the stress response and the decrease in concentration suggests forest bathing promotes parasympathetic activity.
Similar cardiovascular results were also found in a 2016 study. A difference worth noting was an increase in the hormone adiponectin. This hormone is found in adipose (fat) tissue with roles in promoting glucose uptake, insulin sensitivity, fat accumulation and a decrease in glucose output and vascular inflammation. Lower adiponectin levels are found in those with metabolic disease, such as, type 2 diabetes and cardiovascular disease.
Psychological wellbeing
There are also psychological benefits from forest bathing, which have been measured using the Profile of Moods subscale. The subscale consists of tension-anxiety, depression, aggression-hostility, vigor-activity, fatigue and confusion-bewilderment. In forest bathers, there was an improvement in tension, depression, and fatigue and an increase in vigor. This suggests there are positive wellbeing effects with forest bathing.
There appears to be vast physiological and psychological benefits of forest bathing where the improvements are driven by a decrease in sympathetic activity. Next time you want to do something for your health, why not go for an immersive walk in a local park or nature reserve and reap the benefits of forest bathing for different systems in your body? Take a walk, enjoy the smells,sight, sound and feel of the forest.
Further reading for more information
Research articles
Li, Q., Morimoto, K., Kobayashi, M., Inagaki, H., Katsumata, M., Hirata, Y., ... & Kawada, T. (2008). Visiting a forest, but not a city, increases human natural killer activity and expression of anti-cancer proteins. International Journal of Immunopathology and Pharmacology, 21(1), 117-127.
Li, Q., Morimoto, K., Kobayashi, M., Inagaki, H., Katsumata, M., Hirata, Y., ... & Kawada, T. (2008). A forest bathing trip increases human natural killer activity and expression of anti-cancer proteins in female subjects. Journal of Biological Regulators and Homeostatic Agents, 22(1), 45-55.
Park, B. J., Tsunetsugu, Y., Kasetani, T., Kagawa, T., & Miyazaki, Y. (2010). The physiological effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing): evidence from field experiments in 24 forests across Japan. Environmental Health and Preventive Medicine, 15(1), 18–26. doi:10.1007/s12199-009-0086-9
Park, B. J., Tsunetsugu, Y., Kasetani, T., Kagawa, T., & Miyazaki, Y. (2010). The physiological effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing): evidence from field experiments in 24 forests across Japan. Environmental Health and Preventive Medicine, 15(1), 18–26. doi:10.1007/s12199-009-0086-9
Li, Q., Kobayashi, M., Kumeda, S., Ochiai, T., Miura, T., Kagawa, T., … Kawada, T. (2016). Effects of Forest Bathing on Cardiovascular and Metabolic Parameters in Middle-Aged Males. Evidence-based Complementary and Alternative Medicine : eCAM, 2016, 2587381. doi:10.1155/2016/2587381
Forest bathing in the media
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