In the city, parks and green spaces certainly help to reduce the heat and promote biodiversity, but also help to slow down cellular aging according to a study published Wednesday in Science Advances. People living near islands of greenery are on average biologically younger than others by two and a half years.
“Living near more greenery can help you look younger than your true age,” Kyeezu Kim, the study’s lead author, who is a postdoctoral fellow at the university’s medical school, told AFP. Northwestern.
“We believe our findings have important implications for urban planning in expanding green infrastructure, promoting public health, and reducing health disparities,” she added.
A link had already been established between exposure to green spaces and better cardiovascular health as well as lower mortality rates. The researchers believed that physical activity and social interactions related to park attendance played a role in this finding. But whether the parks themselves slow cell aging was unclear.
The team in charge of the study published on Wednesday therefore examined chemical modifications of DNA called “methylation”.
Previous work has shown that “epigenetic clocks” (i.e. the biological age of cells) based on DNA methylation can predict health problems such as cardiovascular disease, cancer or impaired cognitive functions, and represent a more accurate way of measuring age than calendar years.
Disparities in benefits
Kyeezu Kim and his colleagues followed more than 900 people, black and white, from four American cities (Birmingham, Chicago, Minneapolis and Oakland) over 20 years, from 1986 to 2006.
Using satellite images, the team measured the distance between participants’ addresses and parks, and studied blood samples taken in the fifteenth and then the twentieth year of the study to determine their biological ages.
The researchers then built mathematical models to analyze the results and took into account variables that may have affected them such as education, income, smoking or not.
They found that people whose homes were surrounded by 30% greenery within a three-mile radius were on average biologically 2.5 years younger than those whose homes were surrounded by 20% greenery.
But the benefits were not the same for everyone.
Black people living near green spaces were only a year younger than their age, while white people were three years younger.
“Other factors such as stress, the quality of surrounding green spaces and other social factors can affect the magnitude of benefits from green spaces in biological age,” said Kyeezu Kim, adding that these disparities should make the difference. subject of further research.
For example, parks located in deprived neighborhoods and used for illegal activities are likely to be less frequented, and therefore less beneficial.
Future research could examine the link between green spaces and specific health consequences, she said. It’s also unclear how greenery reduces aging, she added; we only know that the impact exists.
Epidemiologist Manuel Franco, from the universities of Alcala and Johns Hopkins, called the study “well designed”. “We have more and better scientific evidence to increase and promote the use of urban green spaces,” said Franco, who was not involved in the study.