A recent study has revealed that residents in neighborhoods with a significantly higher count of trees and shrubs exhibited reduced levels of an inflammation marker in the blood, compared to those living in areas without such greenery. Overall inflammation is a crucial risk factor linked to heart disease and other chronic illnesses.
The University of Louisville’s innovative Green Heart Louisville Project has shown that individuals residing in neighborhoods where tree and shrub quantities increased dramatically had lower blood inflammation marker levels than those in non-planted areas. This general inflammation is a vital risk sign for heart disease and other long-term health conditions.
The Christina Lee Brown Envirome Institute initiated this pioneering project in 2018, teaming up with The Nature Conservancy, Washington University in St. Louis, Hyphae Design Laboratory, among others, to investigate the impact of living in greener environments on heart health. This study’s design closely resembles clinical trials used to evaluate medical treatments. The research team applied the “treatment” of adding substantial trees and shrubs to certain neighborhoods while leaving others unchanged. They then analyzed the communities’ health data to see how these enhancements influenced well-being.
“The Green Heart Louisville Project exemplifies how our university’s forward-thinking and cooperative researchers strive to enhance lives locally and beyond,” stated UofL President Kim Schatzel. “While trees are aesthetically pleasing, this research indicates that surrounding ourselves with trees significantly benefits both individual and community health. Through this project and others, the Envirome Institute works to promote community health, extending its impact beyond individual well-being to everyone in the neighborhood.”
To assess community health at the study’s outset, researchers collected blood, urine, hair, and nail samples and collected health information from 745 individuals living in a four-square-mile area of south Louisville. They also meticulously recorded the area’s tree coverage and air pollution levels.
After gathering this baseline data, the Envirome Institute collaborated with The Nature Conservancy and various local partners to plant over 8,000 large trees and shrubs in selected neighborhoods. Residents in these greening areas were classified as the treated group, and their health results were contrasted with those from nearby neighborhoods where no trees were planted.
After the planting efforts, the research team re-evaluated the residents’ health. They discovered that individuals in the enhanced green areas exhibited 13-20% lower levels of a general inflammation biomarker known as high-sensitivity C-reactive protein (hsCRP) compared to those in neighborhoods without any new greenery. Elevated hsCRP levels are strongly linked to cardiovascular disease risk and are even more indicative of heart attacks than cholesterol levels. Increased CRP levels also indicate a heightened risk for diabetes and certain cancers.
A reduction in hsCRP within this percentage range roughly corresponds to a 10-15% decreased risk of heart attacks, cancer, or mortality from any cause.
“Findings from the Green Heart Louisville Project highlight that trees offer more than mere beauty and shade. They enhance the health of surrounding residents,” commented Aruni Bhatnagar, director of the Envirome Institute and a professor of medicine at UofL. “While several earlier studies have found correlations between high greenery and health, this is the first to demonstrate that a conscious increase in neighborhood greenery can positively affect health. With these findings and the further studies we aim to present soon, we gain a deeper understanding of the influence of local tree density on resident health. This insight will help promote the increase of urban green spaces.”
As research progresses on the health benefits linked to greater tree cover, enhancing green areas in cities may become a crucial strategy for advancing public health.
“Most of us inherently feel that nature is beneficial for our health. Nevertheless, scientific studies confirming and analyzing this link are scarce,” remarked Katharine Hayhoe, chief scientist at The Nature Conservancy. “The latest insights from the Green Heart Project strengthen the scientific argument for the significant relationship between planetary health and individual well-being.”
Earlier in August, the Green Heart Louisville Project received an additional $4.6 million in funding from the National Institute of Environmental Health Sciences to facilitate ongoing research over the next five years.
These findings were shared by Daniel Riggs, assistant professor of environmental medicine at UofL, during the 36th Annual Conference of the International Society for Environmental Epidemiology held in Santiago, Chile on August 26.
