Child/Adolescent Health

Boosting and preserving green spaces in urban neighborhoods may help reduce childhood obesity

Nearly one in five children and youth were obese (95th percentile of national weight standards or higher) in 2003-2004 and one-third were overweight (between the 85th and below the 95th percentile). Providing urban children with more green space to play in may reduce obesity, suggests a new study. Researchers found that low-income, mostly black youth who lived in high-density neighborhoods with abundant green space had lower body mass index (BMI).

The authors measured neighborhood density and normalized difference vegetations index (NDVI, "greenness") derived from satellite images. NDVI was scaled by a factor of 10, so that a 1-unit increase corresponded to urban land-use changes such as from parking lots or industrial sites with little vegetation to school yards with moderate greenness, or from vacant land/right-of-ways to parks with lush vegetation.

More neighborhood greenness was significantly associated with lower BMI 2 years after children's initial BMI measurements. It was also associated with 13 percent lower odds of children and youth having higher BMI 2 years later, perhaps due to increased physical activity and time spent outdoors by children living in greener neighborhoods, note the researchers. Also, greenness might indicate proximity to parks, playfields, or other open spaces that promote either physical activity or increased time spent outdoors in active play. Finally, green landscaping might indicate people care about their homes and this could be linked to increased community surveillance that deters crime and thereby boosts parents' willingness to encourage their children to play outside. Higher residential density, which has been associated with moderate physical activity among adults (due to street connectivity, land-use mix, etc.), was not associated with children's BMI 2 years later, regardless of greenness.

The study was supported in part by the Agency for Healthcare Research and Quality (T32 HS13853).

See "Neighborhood greenness and 2-year changes in body mass index of children and youth," by Janice F. Bell, Ph.D., M.P.H., Jeffrey S. Wilson, Ph.D., and Gilbert C. Liu, M.D., M.S., in the December 2008 American Journal of Preventive Medicine 35(6), pp. 547-553.

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