March 30, 2009

Neighborhood Food Options Linked to Obesity in New York City

Photo of two people at an outdoor fruit stand

Access to stores that sell healthy foods may be a crucial factor in fighting obesity, according to a new study.

About two-thirds of adults nationwide are overweight, and almost one-third are obese. Much attention has been focused on the role of fast food and soft drinks in obesity. A growing body of research suggests that the "built environment" also plays a role—that is, access to stores that sell healthy foods and to resources that support physical activity, such as green spaces.

Researchers at Columbia University led by Dr. Andrew Rundle set out to explore how the food environment relates to weight in New York City, an area with a variety of people and neighborhoods. The researchers tapped the New York Cancer Project for data on height, weight, age, race/ethnicity, gender, income and education for over 13,000 residents of New York City.

The researchers defined a person's neighborhood as a half-mile around his or her home. To form a picture of these areas, they compiled data from several sources, incorporating population information, bus and subway stops, land use information and neighborhood food establishments. The team then analyzed any possible associations between a person's food environment and his or her BMI-a ratio of weight to height often used to estimate body fat. The analysis was supported by NIH's National Institute of Environmental Health Sciences (NIEHS).

The team reported in the March 2009 issue of Environmental Health Perspectives that they found 1 significant association between the food environment and BMI: access to healthy food outlets such as supermarkets, natural food stores and fruit and vegetable markets.

Surprisingly, the researchers didn't uncover an association with unhealthy food outlets such as fast-food restaurants, convenience stores, pizzerias, bakeries and candy and nut stores. However, they note that the lack of association may just reflect the fact that virtually all New York City neighborhoods provide many opportunities for people to eat poorly. Almost 99% of the people in the study lived within a half-mile of an unhealthy food outlet. By contrast, only 82% lived within a half-mile of a healthy food outlet. There were more unhealthy food choices for most people as well, with an average of over 7 unhealthy food outlets for every healthy outlet.

The researchers note that this finding doesn't prove that healthy food choices are responsible for lowering BMI. People who prefer healthy foods may tend to move into neighborhoods with more healthy food outlets. Retailers selling healthy foods, in turn, open where they think the population will be most receptive to their products.

While these results need to be confirmed by future studies, they suggest that increasing access to healthy food outlets could help combat the obesity epidemic more effectively than limiting unhealthy food. Many communities around the country have begun initiatives to promote access to supermarkets, farmers markets, and fruit and vegetable stands. "I see a role for follow-up studies to examine changes in diet and obesity rates in neighborhoods where new supermarkets or produce stores open," Rundle says.

—by Harirson Wein, Ph.D.

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