Where did you go on your last vacation? If you live in the city or the suburbs, there’s a good chance that you spent it in a natural setting, perhaps at a national park, the beach or a cabin in the mountains.

Most of us have felt the inexplicable pull of the outdoors, even if it’s simply prompting us to take a neighborhood walk or sit in the backyard watching the clouds or the squirrels. Nature holds a special kind of energy: it is pure and wild and spirit-renewing.

So why does being in nature feel so good? Is it the peace and quiet, the connection to the earth, the negative ions? Yes, it is all of these, but so much more. New research has found that being in nature actually boosts the immune system, which in turn, increases our mental and physical health.

But first, let’s rewind a bit. Over the last several years, researchers have overwhelmingly confirmed that being in nature is good for one’s mental and physical health. The facts are startling: Simply spending time in parks, gardens and forests is linked to stronger mental and physical health. On the contrary, living in an area with little green space is tied to higher risk of disease, including depression and anxiety, attention deficit/hyperactivity disorder (ADHD), cancer, diabetes, and so much more.

For a long time, however, the scientific connection between nature and good health remained somewhat of a mystery. In order to find the missing link, Ming Kuo, a researcher from the University of Illinois, conducted an analysis on every study she could find on the connection between nature and good health. The link was overwhelmingly clear: It’s the immune system.

In her research, Kuo found as many as 21 possible pathways between nature and good health and all but two of these could be linked to the immune system. She compares being in nature to taking a multivitamin that provides us with all the nutrients our bodies need to simultaneously protect us from all types of physical and mental ailments.

So how does the immune system get a boost from nature? One way is that it switches the body into “rest and digest” mode — the opposite of “fight or flight,” a well-known immune system killer. When we feel content and safe — and not fixated on a problem — the body can invest more energy and resources toward the immune system, rather than wasting all of that precious energy on a work deadline, for example.

Being outside also has inherent immune-boosting qualities such as vitamin D from sunlight, negative ions, phytoncides (healthy antimicrobial compounds derived from plants) and mycobacterium vaccae (good bacteria in the soil).

So what does the immune system have to do with our mental health? The research in this area is overwhelming as well. Scientists from the University of Cambridge, for example, recently found that children who grow up with higher levels of proteins released in the blood during illness are nearly twice as likely to suffer from depression and psychosis as adults. Other studies, including those conducted on mice, have shown that depression is similar to an allergic reaction, occurring as a result of an over-reactive immune system. Rather than getting a runny nose, for instance, some people might experience depression.

No matter whether you are an ocean person, a mountain person or just a backyard garden person, the important thing is that you spend ample time in nature. If you don’t have access to a completely natural setting, simply get out for a walk, sit under a tree or put your bare feet on the ground. Bring live plants or a fish aquarium (also found to improve mental health) into your home. Connecting with nature is a basic human need that reaps enormous health benefits for both the body and the mind.

Kuo’s paper, “How might contact with nature promote human health? Promising mechanisms and a possible central pathway” is published in the journal Frontiers in Psychology.

Woods photo available from Shutterstock

Why Nature is So Good for Your Mental Health