Oct 29 2008
In the first study to look at the effect of neighborhood greenness on inner city children's weight over time, researchers from the Indiana University School of Medicine, Indiana University-Purdue University Indianapolis and the University of Washington report that higher neighborhood greenness is associated with slower increases in children's body mass over a two year period, regardless of residential density.
"Previous work, including our own, has provided snap shots in time, and shown that for children in densely populated cities, the greener the neighborhood, the lower the risk of obesity. Our new study of over 3,800 inner city children revealed that living in areas with green space has a long term positive impact on children's weight and thus health," said Gilbert C. Liu, M.D., senior author of the new study which appears in the December issue of the American Journal of Preventive Medicine. Dr. Liu is assistant professor of pediatrics at the IU School of Medicine and a Regenstrief Institute affiliated scientist.
The new study looked at children ages 3 to 18 years whose residence didn't change over 24 consecutive months. Higher neighborhood greenness was associated with slower increases in body mass index over time, regardless of age, race or sex. This slowing of body mass index could correspond with reduced risk of child obesity in the long term. The inner city children in the study were predominantly African-American, poor, and publically insured.
In a novel partnering of health services research and geographic technologies, the researchers used satellite images to identify and measure greenness. Greenness was not simply defined as parks.
"Our research team adapted methods, originally developed for agricultural and forestry research, to estimate greenness in children's residential environments. These measures are affected by all forms of vegetation that are visible to the satellite and take into consideration not only how much vegetation is present, but how healthy that vegetation is. While other researchers have used similar techniques to study vector-borne diseases, such as malaria, we are among the first to explore this method in health behavior studies," said Jeffrey S. Wilson, Ph.D., associate professor and chair of the Department of Geography at IUPUI's School of Liberal Arts.
Trees and other urban vegetation improve aesthetics, reduce pollution and keep things cooler, making the outside a more attractive place to play, walk or run.
Childhood obesity is associated with a variety of health problems including type 2 diabetes, asthma, hypertension, sleep apnea and emotional distress. Over the past 30 years, obesity has doubled in children age 2 to 5 and age 12 to 19 years and has tripled in children between 6 and 11 years of age, according to the Institute of Medicine.
Obese child are likely to be obese as adults increasing risk for cardiovascular disease, high blood pressure, stroke and higher health care costs.
"Obesity is a national epidemic necessitating the involvement of health-care providers, parents, and the community. Our lifestyle makes us sedentary and less healthy. For children, physical activity is active play and that usually take place outdoors. We need to encourage them to go outside and play. I love the idea that we can landscape for health," said Dr. Liu, a pediatrician who sees patients at both Riley Hospital for Children and Wishard Health Services.
Dr. Liu, Dr. Wilson and study co-author Janice F. Bell, Ph.D., MPH, of the University of Washington, note that further research is required to understand the mechanisms underlying associations between neighborhood greenness and childhood obesity. They write, "Ideally, this research will be multidisciplinary – involving city planners, architects, geographers, psychologists and public health researchers – and will consider the ways children live and play in urban environments."