Living Near Green Space May Slow Biological Aging

People who live in places surrounded by greenery may have a lower biological age, a new study suggests.

Previous research has associated living close to parks and other green space with many benefits for healthy aging, including better cardiovascular health and lower mortality.

The new study from the Northwestern University Feinberg School of Medicine researchers found that people who lived near more green spaces were biologically 2.5 years younger, on average, compared to those who lived around less greenery.

"When we think about staying healthy as we get older, we usually focus on things like eating well, exercising and getting enough sleep," says Kyeezu Kim, first author on the study and a postdoctoral scholar in preventive medicine at Northwestern University Feinberg School of Medicine. "However, our research shows that the environment we live in, specifically our community and access to green spaces, is also important for staying healthy as we age."

Published in the peer-reviewed journal Science Advances, the study investigated how 20-year exposure to greenness affects biological aging. Specifically, the researchers used DNA methylation-based epigenetic age, which refers to chemical changes in DNA that may influence various age-related health outcomes. To estimate the participants' epigenetic age, the researchers analyzed their blood DNA methylation tests.

The study included 924 participants who lived across four cities in the United States: Birmingham, Alabama.; Chicago; Minneapolis; and Oakland, California.

Using satellite imaging, the researchers were able to quantify the overall vegetation (greenness proportion) and the presence of major parks within the 5 km (3.1 miles) of the participants' residences.

The study found that the benefits of greenery depend on race, sex, and socioeconomic status. For example, Black participants had less greenness than white individuals, suggesting that limited access to green spaces could result in less improvement in epigenetic aging.

Additionally, women living in green areas saw a greater reduction in their biological age compared to men. One possible explanation is that traditional social roles as caregivers might increase the use of residential surrounding greenness.

However, the researchers did not analyze the quality of greenness or the type of green spaces, even though it could better explain the association between surrounding greenery and biological aging. Moreover, factors not measured in this study, such as stress and social network, may also affect biological age.

Study authors say their findings suggest that urban planning should include expansion of green infrastructure to improve life span.