For green spaces to be most beneficial to health, they need to be walkable

The positive health impact of green space isn't just about where you live, but how easily you can access nature, according to new research.

Previous studies have suggested that simply living in neighborhoods filled with trees, grass and plants can reduce heart disease risk. For the new study, researchers explored the relationship between green space and cardiovascular risk factors and diseases by using two metrics: NatureScore, a composite measure of the amount and quality of nature, and walk score, which gauges how easy or hard it is to walk around a neighborhood.

Researchers looked at a medical database of more than 1 million adults in the Houston metro area who were 52 years old on average. Based on where they lived, each person was categorized by a NatureScore of nature-deficient, nature-adequate, nature-rich or nature-utopia, as well as a walk score of car-dependent for all errands, car-dependent for most errands, somewhat walkable or very walkable/walker's paradise.

When researchers looked simply at green space, they found cardiovascular diseases and risk factors were actually more common in people living in neighborhoods with a high NatureScore, compared with those living in less green neighborhoods – a surprising finding, said lead researcher Dr. Omar Mohamed Makram, an internal medicine resident at the Medical College of Georgia at Augusta University and a former postdoctoral fellow at the Center for Health and Nature at Houston Methodist Hospital.

But when walkability scores were factored in, people living in the highest NatureScore areas had 9% lower odds of cardiovascular disease risk factors such as high blood pressure, high cholesterol, obesity and diabetes than those living in the lowest NatureScore areas. They also had 4% lower odds of cardiovascular diseases, which included coronary heart disease,...