Study: No magic bullet to improve diet, stem obesity epidemic

(Medical Xpress) -- Will people eat healthier foods if fresh fruits and vegetables are available in stores near their homes? Will they eat less fast food if restaurants are not in their neighborhoods?

These and other policy interventions may be useful steps toward better public health, but no single approach alone will effectively improve Americans’ diets or stem the obesity epidemic, concludes a study by researchers at the University of North Carolina at Chapel Hill.

In a report released July 11 in the journal Archives of Internal Medicine,nutrition researchers from UNC’s Gillings School of Global Public Health found that having access to neighborhood grocery stores or larger supermarkets alone did not make a significant change in dietary habits. Living near fast food restaurants seemed to increase the amount of fast food consumed by lower income males, but findings were mixed across other groups, said Penny Gordon-Larsen, Ph.D., the study’s senior author.

“Our study did not examine the quality of foods offered or the purchasing patterns at fast food restaurants, supermarkets and grocery stores,” Gordon-Larsen said. “We only examined the availability of fast food restaurants, supermarkets and smaller grocery stores. What we can conclude, though, is that simply introducing a supermarket in a neighborhood may not be enough – the new store should be accompanied with multifaceted efforts, such as promotion, education and incentives for healthier options.”

According to background information in the article, the federal government has made one of its priorities reducing “food deserts,” areas in which healthy food is difficult to find. “Such policies stem from limited evidence that food resources are related to obesity and are inequitably allocated according to neighborhood wealth,” wrote the authors. “Implicit in these policy initiatives is that reduced access to fast food and increased access to supermarkets will translate into improvements in diet behavior and health.”

Janne Boone-Heinonen, Ph.D., a postdoctoral fellow at UNC’s Inter-Disciplinary Obesity Center, and colleagues assessed this assumption using data from the Coronary Artery Risk Development in Young Adults study, from its baseline in 1985 until 2001. The authors evaluated fast food consumption, diet quality and adherence to fruit-and-vegetable-consumption guidelines as a function of fast food chain, supermarket or grocery store availability within distances of less than one kilometer to more than eight kilometers from study participants’ homes. The 5,115 participants (ages 18 to 30 years at baseline) in Birmingham, Ala.; Chicago; Minneapolis; and Oakland, Calif., were asked how often they ate fast food, and detailed their food consumption during the prior month as well as usual dietary habits.

Among lower income participants, the study found an association between fast food consumption and fast food availability. This relationship was particularly noticeable among men who had access to fast food between one and three kilometers from where they live. The findings did not suggest strong relationships between supermarkets and diet quality or consumption of fruits and vegetables. Availability of grocery stores had a mixed relationship with eating habits.

“Our findings suggest that no single approach, such as just having access to fresh fruits and veggies, might be effective in changing the way people eat,” Gordon-Larsen said. “We really need to look at numerous ways of changing diet behaviors. There are likely more effective ways to influence what people eat.

“For example, classifying foods as healthy or unhealthy depending on whether they are served as fast food or in a sit-down restaurant may not paint the whole picture. Maybe we need to be looking more closely at what they are ordering and the prices they pay for healthy versus less healthy foods. It is very clear that we need to find ways to improve diets, particularly of low income individuals. Simply putting in extra supermarkets per se may not solve the current health inequities. More research is needed.”