‘Go play outside. Fresh air is good for you!’ How often did you hear this from your mom? Well it turns out, she was right! Getting outside isn’t just good for the soul. It’s good for a lot of other health benefits too and now science is proving that being in nature is vital to good health.
There have been many hypotheses over the years as to why being in nature improves mental health, lowers blood pressure and triggers the parasympathetic nervous system which promotes relaxation. These effects have all been proven by numerous studies. But the question remains: why?
In Japan, Shinrin yoku, or forest bathing, is a popular practice and research now points to a reason why it’s good for you. It turns out that the fresh, earthy smell you experience in the outdoor environment is the reason. The smell comes from phytoncides which are released from trees and plants and linked to improved health.
Phytoncides are known to increase the immune system’s anti-cancer ‘Natural Killer’ (NK) cells. And the effect is lasting. A study by Quin-Li of the Nippon Medical School showed that after exposure to a forest environment, “The increased NK activity lasted for more than 30 days … suggesting that a forest bathing trip once a month would enable individuals to maintain a higher level of NK activity. In contrast, a visit to the city as a tourist did not increase NK activity.”
Just being in a green space increases your exposure to a range of micro-organisms that could impact both your immune system and have an anti-inflammatory impact. In addition, negative air ions which are plentiful within forested regions, near moving water and around mountains have a positive effect on depression. A Stanford University study in 2015 showed that walking in a forested area reduced the risk of depression.
“Blood tests before and after walks in different environments reveal that levels of health-protective factors increase after forest but not urban walks,” says University of Illinois professor Ming Kuo in an article in Frontiers in Psychology. “DHEA increases after a forest walk.” DHEA is a hormone that has anti-inflammatory, anti-obesity and anti-diabetic properties. It may also have cardio-protective properties.
“Time spent in and around tree-lined streets, gardens, parks, and forested and agricultural lands is consistently linked to objective, long-term health outcomes,” says Kuo. “The less green a person’s surroundings, the higher their risk of morbidity and mortality – even when controlling for socioeconomic status and other possible confounding variables.”
Dr. Kuo points out that there are many health conditions with positive outcomes tied to nature including depression and anxiety disorders, diabetes, ADHD, cancer, respiratory disease, cardiovascular disease and others.
Unsurprisingly, it turns out the more time you spend in nature the bigger the health gain. A Chinese study showed that after seven days of forest immersion, inflammatory cytokines decreased by approximately 50 per cent. Cytokines play a role in chronic diseases such as diabetes, depression, heart disease and others.
With scientists now having a clearer understanding about the benefits of being in nature, the health profession is jumping on board. In late 2018, doctors in the U.K. began prescribing ‘nature’ to patients with a range of conditions including anxiety, depression and high blood pressure. Other medical practitioners could soon follow suit.
It’s ironic that the simple act of being in nature can manage some of life’s most complex health problems. Mom was right all along – all you really need to do is go outside. Shinrin yoku anyone?