Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
For perhaps 99.99 percent of our time on Earth as a species, we’ve been living outdoors in the natural environment. Might there be a health benefit to returning now and again, and surrounding ourselves with nature? That’s a question urban planners have asked: Are people living in greener areas healthier than people living in less green areas? Should we put in a park or another carpark?
In a greener environment, people report fewer symptoms of illness, and have better perceived general and mental health––and by a considerable amount. Assuming the link is cause and effect, 10 percent more greenspace leads to a decrease in the number of symptoms that is comparable with a decrease in age by five years, but that is a big assumption.
Still, you could imagine some potential mechanisms of why it could be. It could mean less air pollution. And air pollution is no joke; it is the fifth leading cause of death on planet Earth, wiping out about five million people a year. Though, of course, our diet kills twice as many, as killer risk factor #1.
So, it could be an antipollution effect. Or maybe there’s something special about experiencing greenspaces, beyond them just offering more opportunities to exercise. But that’s probably the simplest explanation: natural settings simply promote “health-enhancing behavior rather than having specific and direct benefits for health.” It’s harder to go jogging in the park when there is no park. Ironically, it seems that even when people have access to nature, they don’t necessarily take advantage of it. And, even if there was a link, instead of natural environments drawing out increased physical activity, maybe physically active individuals are just drawn to living where there’s nature. But what I wanted to know is, apart from the promotion of physical activity, are there added benefits to health of mere exposure to natural environments?
Now certainly, just exposure to sunlight can treat things like seasonal aﬀective disorder, and provide the sunshine vitamin—vitamin D. But are there any other inherent benefits? You don’t know, until you put it to the test. Some of the studies are just silly, though. At first, I thought this was about academic achievement and vegetarianism, but no—it’s vegetation. They found a correlation between non-forest vegetation and graduation rates for schools. Maybe the Ivy League edge is all just ‘cause the ivy.
Okay, but this study starts to make things more interesting. The view through a window may influence recovery from surgery. At this suburban hospital, some patient rooms looked out at trees, and others just to a brick wall. And, the “surgical patients assigned to rooms with windows looking out on a natural scene had shorter postoperative hospital stays” and took fewer potent painkillers than similar patients in similar rooms, but with windows facing the brick wall. You can’t chalk that up to a vitamin D effect.
What could it be about just looking at trees? Maybe it’s the vitamin G, just the color of green. We know how healthy it is to eat our greens. What about just looking at them? Researchers had people exercise while watching a video simulating going through a natural-color green setting, the same video in black and white, or everything flipped to red, and…no differences were noted (with the exception of the red just making people feel angry).
The most interesting suggested mechanism I ran across was fractals. You know how all the branches of a tree kind of have the same shape of a tree themselves? Fractal patterns are found throughout nature, where you see a cascade of self-similar patterns over a range of magniﬁcations. And hook people up to an EEG, and for some reason our brain apparently seems to like them.
Regardless of the mechanism, if you compile together all the controlled studies on using nature as a health promotion intervention, you tend to see mostly psychological benefits, whereas the findings related to physical outcomes were less consistent. The most common type of study outcome was self-reported measures of different emotions. Like, what makes you feel better, staring at a kiwifruit orchard, or staring at a building? Awkwardly described, thanks presumably to the language barrier, as a comparison of “synthetic versus organic stimulation.”
Natural settings may make people more attentive, less sad, but when it comes to some objective measures like blood pressure, no significant effect. So, you know, you ask people who exercise outdoors, and they say they feel great, suggesting that “green exercise” activities have the capacity to increase mood, focus, and energy, and within just like five minutes of being out there in the woods.
Yet these studies tended not to be randomized trials. They just asked people who already sought out nature what they thought about nature; and so, no wonder they like it—otherwise they wouldn’t be out there. But hey, nature-based interventions are low-cost––often free in fact––and non-invasive (unless you count the mosquitoes). So, if you want “a natural high,” I say go for it; whatever makes you happy. (Though evidently not all green exercisers like trees. Golfers just viewed them as obstacles.)
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