"By focusing on these inflammation markers, the study provides a biological explanation for why nature might improve health," said Anthony Ong, professor of psychology, "particularly showing how it might prevent or manage diseases linked to chronic inflammation, like heart disease and diabetes."

For their study, the team used the second wave of the Midlife in the U.S. (MIDUS) survey, a longitudinal study of health and aging in the United States. Ong's analyses focused on a subset of individuals - 1,244 participants, 57% women, with a mean age of 54.5.

The participants were asked how often they experienced being out in nature, as well as how much enjoyment they got from it. Even when controlling for other variables such as demographics, health behaviors, medication and general well-being, Ong said his team found that reduced levels of inflammation were consistently associated with more frequent positive contact with nature.

"It's a pretty robust finding," Ong said. "And it's this sort of nexus of exposure and experience: It's only when you have both, when you are engaging and taking the enjoyment out of it, that you see these benefits."