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The Effects of Nature Exposure on Disease Prevention & Health Promotion



There is a certain phenomenon that we all feel if we pay attention when we are in a natural environment. We feel more quiet, at peace, connected and relaxed in the forest. The quiet atmosphere, subtle sounds of leaves in the trees, beautiful scenery that we observe, pleasant natural aromas, and freshness of the air permeates our mentality and calms us down.


This is not just a feeling of appreciation. There are measurable forces at play that have a scientifically proven effect on our mental and physical health and well-being. For decades, Japan has heavily funded research to discover why exactly human being suffer when separated from nature, investigating the effect of being in a forest environment.


This practice has come to be known as "Shinrin-Yoku" (Forest Bathing), and has since bloomed into a form of widely accepted form of preventative, alternative medicine, categorized as environmental medicine, or Forest Medicine. Japan's research on the subject has since inspired the governments of many countries to fund their own research on the subject, and today, there is a plethora of undeniable research supporting the claims of a physiological, and psychological benefit of spending time in nature.


Here are the main findings, in a nutshell, regarding the scope of benefits to human health that Shinrin-Yoku offers.


Phytoncides are antimicrobial compounds that protect plants and trees from harmful bacteria and diseases. These compounds are found in the essential oils of plants and are airborne when we are surrounded by trees and plants in a natural setting. When human beings are exposed to phytoncides, it has been found to increase human natural killer (NK) cells, and the levels of anti-cancer proteins. This infers that time spent in nature carries a preventative effect on cancers. NK cells are a type of white blood cell that defends the body against invasive bacteria and viruses, and function to stop the spread of microbial infections and control the growth of tumors. There is even recent research showing a preventative effect on COVID-19, not only through the action of phytoncides, but also through the general effect of boosting our immune system and reducing mental stress.



Spending time in nature has also been proven to reduce blood pressure and heart rate, giving us the benefit of preventing hypertension and heart disease. Another result of forest therapy is reducing stress hormones, measured through urinary adrenaline and noradrenaline, as well as salivary cortisol, which has a significant effect on managing stress levels.


Being in nature also reduces the activity of our sympathetic nerves, which is the part of our autonomic nervous system that activates our stress and survival response. Sympathetic nerve stimulation is what keeps us in a low-grade state of fight or flight. This is what we want during a short term period if we are fighting for our lives, but when we are subjected to social pressures, and the stress of living in modern society, it's easy to be stuck in this "mode" of our autonomic nervous system. Forest bathing, conversely, stimulates the activity of the parasympathetic nervous system, which relaxes us, and reduces our levels of stress. This is the other side of the coin of our autonomic nervous system; the rest and digest state. The effect of being in nature stabilizes the balance of our autonomic nervous system. A much needed effect in our modern society. This also improves the quality of our sleep.


Shinrin-Yoku also increases levels of adiponectin, a hormone which plays a critical role in protecting against insulin resistance, and atherosclerosis. This reduces the risk of diabetes, heart attacks and strokes. Perhaps a big reason why these diseases are a big problem in our modern time isn't just dietary, but our relatively recent disconnection with nature.


It also increases levels of dehydroepiandrosterone sulfate (DHEA), which is a natural steroid produced by our bodies. Low levels of DHEA are linked with low bone density, depression, adrenal insufficiency, certain forms of cancer, sexual dysfunction, and numerous diseases. It's questionable if boosting DHEA through health supplements is actually effective in helping to regulate low DHEA levels in the body, but forest bathing has proven to be an effective means of doing so.


There is a test called the Profile of Mood States test (POMS), which is a subjective test based on questioning individuals, so take this as it is. In studies, this test has been taken before and after Shinrin-Yoku sessions and has shown to reduce scores for anxiety, depression, anger, fear, and confusion, while increasing scores for vigor. The implication on this shows a clear preventative effect when it comes to clinical depression, if practiced regularly.



These findings together suggest that spending time in nature may have a general preventative effect on reducing the risk of developing non-communicable diseases.


This just scratches the surface, and there are so many more layers to consider when it comes to the benefit of nature exposure. Even spending time in city parks has been shown to reap some of these benefits.


You don't need a guide, or to learn a technique to benefit from spending time in nature. You just need to get out there on a regular basis. 5.5 hours per month is suggested to maintain health, and without this bare minimum, we are operating at a deficit to what our level of health could potentially be. There is no supplement for this, so try to find a way to work this into your life. This can mean 10 minutes a day, strolling through a park, or your garden, or just over an hour once a week going for a slow hike.


To put this into practice, don't rush when you get out there. Don't walk like you have a destination to get to. Slow down, relax, stop whenever you feel called to enjoy the scenery and environment. An hour practicing Shinrin-Yoku might take you less than a kilometer, it might involve a short walk just to find your favorite place to sit and relax. Enjoy and unplug.


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