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Massive Study Reveals Exposure to Nature Has Significant Health Benefits

There’s a reason why being outdoors in nature feels so good — it’s great for your health on multiple levels. A massive study involving data from more than 140 studies and 290 million people revealed that exposure to greenspace, defined as open, undeveloped land with natural vegetation, led to significant reductions in diastolic blood pressure (the bottom number), salivary cortisol (a physiological marker of stress) and heart rate, along with significant decreases in Type 2 diabetes and mortality from all causes and those specifically related to the heart.1

The risk of premature birth also declined in pregnant women, as did the risk of having a baby small in size for their gestational age. Incidences of good self-reported health, meanwhile, rose among those lucky enough to have greenspace exposure. When other health outcomes were factored in, between 66 percent and 100 percent of the studies showed that increased greenspace exposure was associated with better health, including improved outcomes for neurological disorders, cancer and respiratory mortality.

‘Green Prescriptions’ Could Improve Your Health

Wouldn’t it be a breath of fresh air (literally!) if your doctor prescribed you a “green prescription” instead of a prescription drug? According to the featured study, “Green prescriptions involving greenspace use may have substantial benefits.” It’s not a new idea; quite to the contrary, the benefits of spending time in nature have been recognized since the early 1800s, when open spaces and parks started to be created in growing cities like London.2

Modern cities, too, are increasingly seeking to incorporate green space into their planning. As the World Health Organization (WHO) notes, parks, woods, wetlands, meadows and other green spaces contribute oxygen to the air while filtering out air pollution. They also help to moderate temperatures and cool cities, while providing areas where people can safely exercise and interact socially.

“Green spaces also are important to mental health,” WHO states. “Having access to green spaces can reduce health inequalities, improve well-being, and aid in treatment of mental illness. Some analysis suggests that physical activity in a natural environment can help remedy mild depression and reduce physiological stress indicators.”3

You may also have heard of the “Healthy Parks, Healthy People” movement put out by the U.S. National Park Service (NPS), which encourages people to spend time in parks and public lands to create healthy societies. The benefits of park time shared by NPS include:4

  • Improved your mood
  • Improved physical, mental and spiritual health
  • Increased social connections, which add to community cohesion
  • Encouraging active play in children, which is linked to physical, cognitive and social benefits
  • Improved social well-being

There’s even a ParkRx, or Park Prescriptions, movement, created via a collaboration between the Institute at the Golden Gate, the National Recreation and Park Association and NPS, which involves just what its name suggests: a health or social services provider giving a patient or client a “prescription” to spend more time in nature in order to improve their physical health and well-being. Professor Andy Jones of the University of East Anglia (UAE) in England, who co-wrote the featured study, stated:5

"We often reach for medication when we're unwell but exposure to health-promoting environments is increasingly recognized as both preventing and helping treat disease. Our study shows that the size of these benefits can be enough to have a meaningful clinical impact."

Why ‘Forest Bathing’ Is so Good for You

In Japan, a practice known as Shinrin-yoku, or forest bathing, which is another term for spending time in nature, is incredibly popular. In a study that compared the health effects of spending time in a forest versus spending time in a city, the forest environment was found to promote lower concentrations of cortisol, lower pulse rate, lower blood pressure, greater parasympathetic nerve activity and lower sympathetic nerve activity.6

Forest bathing has also been shown to offer relaxation effects while decreasing symptoms of depression, fatigue, anxiety and confusion in middle-aged men.7

It’s even been found that visiting a forest increases the activity of natural killer cells, a part of the immune system, as well as the expression of anticancer proteins — beneficial effects that persisted for at least seven days after the visit to the forest.8 Volatile compounds called phytoncides, such as alpha-pinene and beta-pinene, are released from trees and found in forest air.9

They’ve been shown to reduce stress hormones and anxiety while improving blood pressure and immunity, according to Dr. Eva Selhub, a lecturer in medicine at Harvard Medical School and a clinical associate of Massachusetts General Hospital.10

It’s thought that phytoncides released from trees, as well as reductions in stress hormone, may be partly responsible for the increased activity of killer cells.11 When nearly 500 volunteers spent time in a forest, they experienced significant reductions in stress levels, including lower scores in feelings of hostility and depression. 

The researchers described forests as “therapeutic landscapes” and said they could be extremely advantageous for dealing with acute emotions, especially for people with chronic stress.12 It could be that this reconnection to nature is helping to solve the disconnect many people feel when they’re removed from nature. According to researchers in the International Journal of Environmental Research and Public Health:13

“Humans have evolved into what they are today after the passage of 6 to 7 million years. If we define the beginning of urbanization as the rise of the industrial revolution, less than 0.01 percent of our species’ history has been spent in modern surroundings. Humans have spent over 99.99 percent of their time living in the natural environment. 

The gap between the natural setting, for which our physiological functions are adapted, and the highly urbanized and artificial setting that we inhabit is a contributing cause of the ‘stress state’ in modern people … We believe that nature therapy will play an increasingly important role in preventive medicine in the future.”

It’s also possible that exposure to microbes in the natural environment are providing some of the protective effects. Ambient bacteria, such as Mycobacterium vaccae, for instance, has been shown to reduce anxiety-related behavior and improve learning in mice,14 and it’s possible people inhale such mood-boosting hormones when they’re outside playing or working in the dirt. 

“[E]xposure to a diverse variety of bacteria present in natural areas may also have benefits for the immune system and reduce inflammation,” said featured study author Caoimhe Twohig-Bennett, from UEA's Norwich Medical School.15