For a growing number of people, contact with nature is a novelty that occurs sporadically, perhaps on a yearly vacation to the beach or a trip to the mountains. With increasing urbanization, we are spending more and more time indoors, and far less time in wild, natural places. An emerging body of research indicates that we should not treat nature exposure as a novelty; rather, it should be an integral part of our daily lives, especially considering the many health benefits nature has to offer.
How green are your surroundings?
A multitude of studies demonstrate that exposure green surroundings, such as tree-filled neighborhoods, gardens, parks, and forested land, is associated with positive long-term health outcomes. Conversely, the less green a person’s surroundings are, the higher their risk of morbidity and mortality. (1) A wide range of health conditions have been associated with a lack of nature exposure, including depression, anxiety, Type 2 diabetes, ADHD, infectious diseases, cancer, poor healing outcomes from surgery, obesity, birth outcomes, cardiovascular disease, migraines, and respiratory disease. These findings indicate that contact with nature is a major determinant of health; in fact, “Greening” of human surroundings, including neighborhoods, workplaces, and cities, may constitute a powerful and inexpensive public health intervention. Central Park in New York City is just one long-standing example of "green initiatives" occurring in urban environments.
How does contact with nature promote health?
Scientific research has identified numerous pathways by which nature exposure may promote health. These include the following:
- Plants release airborne chemicals that benefit human health. Plants give off antimicrobial volatile organic compounds called phytoncides. Phytoncides have been found to reduce blood pressure, normalize nervous system activity, and boost immunity. Spending time in an area rich in plants causes you to breathe in these compounds, thus reaping their health benefits. (2)(3)(4)
- The air in forested and mountainous areas, and near running water, contain high levels of negative ions. Ions are atoms or molecules in which the number of electrons (negatively charged particles) is different from the number of protons (positively charged particles). While positive and negative ions must always exist in balance with one another, certain settings may contain a preponderance of one type over the other. For example, technological devices such as TVs and computers give off positive ions, whereas natural settings are richer in negative ions. Exposure to negative ions has been associated with several different health benefits, including improvements in mental health and immune function. Negative ions exert beneficial physiological effects by regulating levels of reactive oxygen species (ROS), which cause damage when present in high concentrations, and by producing electronic excitation, which is used to power biochemical processes in the body. (5)
- Contact with nature increases the body’s microbial diversity. The human body harbors large, diverse microbial ecosystems both on the skin and in the gut. Spending time in nature beneficially modulates the types of microbes that inhabit our skin and gut microbiomes, ultimately affecting our immune systems and conferring protection against asthma, allergic, and autoimmune diseases. (6)
- The sights and sounds of nature calm the nervous system. Simply viewing images of nature has been found to reduce sympathetic nervous system activity (aka the “flight or fight” response) and increase parasympathetic nervous activity (the “rest and digest” response). (7)(8) Listening to nature sounds also increases the “rest and digest” response. (9) Spending time in nature combines the benefits of natural sights and sounds with benefits of phytoncides, negative ions, and increased microbial exposure.
- Time in nature increases DHEA, adiponectin, and natural killer cell activity. DHEA is a heart-protective hormone that also plays a role in the prevention of obesity and diabetes. Adiponectin is a hormone that regulates insulin sensitivity and is lower in obese and diabetic people. Natural killer cells are immune cells that play crucial roles in cancer prevention and defense against pathogenic microbes. Regular time in nature may help maintain optimal levels of these hormones and cells, thus exerting long-term benefits on several facets of health. (10)
- Time in nature decreases inflammatory cytokines and blood glucose. Inflammatory cytokines are released by the immune system in response to threats such as pathogenic microbes, and when chronically elevated, contribute to the development of inflammatory diseases. Elevated blood glucose carries many health risks, including diabetes, nerve damage, and kidney failure. Simply taking regular walks in nature may, therefore, be an effective preventive “prescription” for chronic inflammatory diseases. (11)(12)
The many pathways by which contact with nature promotes health indicates that regular “nature time” should be a key part of a healthy lifestyle. Spending large amounts of time in nature has been a key part of my own healing process. Have you experienced healing benefits from spending time in nature? Let me know in the comments below.