The length of a person’s telomeres — protective caps on the ends of DNA in their cells — is a marker of stress and age. And people living in places with plentiful green space have longer telomeres, a new analysis finds. But green space alone isn’t enough to buffer the health effects of social and physical factors such as discrimination, past redlining and pollution, the researchers warn.
The study, published in Science of the Total Environment, used data from the National Health and Nutrition Examination Survey, which took biological samples from participants from 1999 through 2001. Researchers analyzed telomere length data from 7,827 adult participants’ DNA, matching that data to demographic and neighborhood information.
Living near green space has long been associated with better health and linked to everything from lower stroke risk and cardiovascular disease rates to better sleep quality and mental health. In the study, participants living in greener areas had longer telomeres than their counterparts in other neighborhoods.
“Greenspace could reduce a person’s biological age by 2.2 to 2.6 years,” the researchers write, noting that longer telomeres could confer some of the health benefits associated with green space.
Telomeres are chains of repetitive DNA sequences at the ends of chromosomes. They become slightly shorter every time a cell divides, and once they get too short, the cell that contains them can no longer divide. This can lead to inflammation, age-related diseases and degenerative disorders. Although researchers are still teasing out the relationship between telomere length and health, they are considered an important marker of biological age and cellular stress.
But along with the positive news about green space and telomeres, the researchers write that green space itself is not powerful enough to counteract the health effects of neighborhood variables such as segregation, deprivation and the legacies of discriminatory housing policies. Once the researchers adjusted for those factors, they say, the effect of living near green space vanished.
“Greenspace is tremendously valuable for a community, but it is not enough to overcome systemic racism and the effects of economic segregation and environmental justice challenges on its own,” co-author Aaron Hipp, a professor at North Carolina State University’s College of Natural Resources, said in a news release.
Those factors may “overwhelm any beneficial impact that comes from exposure to greenspace,” the researchers write.
More research is needed to tease out the effects of neighborhood factors and green-space exposure on individual health, they conclude.