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Neighborhoods with fast-food chains may raise risk

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New research finds that neighborhoods with a large density of fast-food outlets are associated with a higher risk of type 2 diabetes. smodj/Getty Images
  • A large study of veterans in the United States made important associations between neighborhood food sources and the incidence of type 2 diabetes.
  • Researchers studied veterans living in rural, suburban, and high- and low-density urban neighborhoods.
  • They linked a higher proportion of fast-food restaurants to a rise in type 2 diabetes in all community types.
  • An increased density of supermarkets compared with other food stores was associated with lower levels of type 2 diabetes in suburban and rural communities.

New York University (NYU) scientists leveraged the power of the Veterans Health Administration to study people’s risk of developing type 2 diabetes based on their neighborhood food environment. First author Rania Kanchi, MPH, and her colleagues recounted their work in the Journal of the American Medical Association Network Open.

Prior studies had discovered that better neighborhood resources, such as healthy food and exercise availability, were associated with reduced diabetes risk. However, these studies were limited to geographically similar, urban-only environments.

Principal investigator Dr. Lorna E. Thorpe, MPH, Ph.D., and her NYU colleagues took a new tack in this unique research design.

Using the Veterans Administration Diabetes Risk cohort — a group of veterans who did not have diabetes — they observed 4,100,650 people. Then, they used United States Census Bureau data to measure food environments and stratify neighborhoods into rural, suburban, and high- and low-density urban areas.

Dr. Thorpe, director of the Division of Epidemiology and vice-chair of strategy and planning in the Department of Population Health at NYU’s Grossman School of Medicine, told Medical News Today:

“Only a few longitudinal studies have tracked the emergence of diabetes among people who live in certain environments and rigorously assessed the role of those environments on diabetes risk. Ours is among the largest, harnessing electronic health records of veterans. [A] key strength is that we were able to assess how these relationships differed across the urban and rural spectrum.”

First, researchers calculated the 5-year average number of fast-food restaurants in veterans’ neighborhoods compared to all restaurants. Then, they documented the proportion of food outlets that were supermarkets over the same timeline.

Researchers accounted for covariates — variables that could influence the study’s outcome — including education levels attained, percentage of unemployment, low income, need for public assistance, and lack of a car. The scientists also adjusted their study for age, sex, race, ethnicity, and disability, among other variables.

The people in the study were predominantly male (92.2%) and non-Hispanic white (76.3%). Additionally, more than 70% of the veterans studied were living with a disability (34.8%) or a low income (37.9%).

Scientists observed the veterans for over 5 years. They found that 539,369 veterans (13.2%) developed diabetes, most commonly among those aged 60–79 (17%), with people aged 40–59 close behind (14.9%).

There were dividing lines among ethnic and minoritized groups. For example, non-Hispanic Black adults had the highest incidence of type 2 diabetes (16.9%), followed by non-Hispanic Native Hawaiian and Pacific Islanders (15%) and non-Hispanic American Indian and Alaskan Native participants (14.2%).

Type 2 diabetes developed in lower amounts among non-Hispanic white (12.9%), non-Hispanic Asian (12.8%), and Hispanic (12.8%) veterans. Notably, 13.6% of men developed type 2 diabetes compared with only 8.2% of women. Finally, veterans living with a disability and a low income were also more likely to develop type 2 diabetes.

The proportion of supermarkets compared to retail food outlets was approximately equal across community types at about 10%. However, the proportion of fast-food restaurants relative to other restaurants broke down as follows:

  • 26% in high-density urban communities
  • 31% in low-density urban communities
  • 32% in suburban communities
  • 29% in rural communities

Overall, an increase in the presence of fast-food restaurants compared with all restaurants was associated with an increased risk of type 2 diabetes in all four communities.

With a 10% increase in the number of fast-food restaurants relative to other restaurants, the scientists observed:

  • a 1% increase in type 2 diabetes risk in rural, high-density, and low-density urban areas
  • a 2% increase in type 2 diabetes risk in suburban communities

Those living in high-density urban areas had the highest incidence of type 2 diabetes (14.3%). Next in line were low-density urban (13.1%) and rural dwellers (13.2%). The lowest incidence of type 2 diabetes was among suburban veterans (12.6%).

Increased supermarket density relative to other food stores was associated with a lower risk of type 2 diabetes among suburban and rural communities, but not for urban communities.

Dr. Thorpe explained to MNT, “The relative mix of food outlets in one’s community does increase or decrease [the] risk for diabetes over time — above and beyond an individual’s risk profile, and that is in general modifiable through programs and policy.” She added:

“High proportions of restaurants being fast food led to a greater risk of diabetes, irrespective of how rural or urban [an area one lives in], and supermarkets seemed to play a particularly strong preventive role in suburban and rural areas.”

In summarizing the complexities of the study, the authors observe that their findings suggest health policy specific to fast-food restaurants could be effective. Dr. Thorpe noted, “Opportunities exist to either alter types of food available in fast-food restaurants or, more difficult, alter zoning laws to restrict the availability of fast-food restaurants to reduce [diabetes] risk.” She continued:

“In non-urban settings, because the relative availability of supermarkets reduces diabetes risk, it may be important to:

  • improve the mix of healthy vs. unhealthy foods at supermarkets
  • improve transportation options
  • increase supermarket availability
  • or introduce a combination of [the above].”

Dr. Thorpe also spoke to MNT about steps individuals can take to reduce their neighborhood-based risk of developing type 2 diabetes:

“For individual residents: Play close attention to how [the] availability of food outlets affects your day-to-day choices, and build practices to take advantage of healthy options in your communities.”

The authors endorse the strength of this study as being their ability to observe veterans and their food environment over a long period. However, regarding limitations, the scientists could not assess the veterans’ diets, physical activity, and coexisting illnesses. Also, the researchers could not determine how often veterans used supermarkets in their neighborhoods.

The scientists see opportunities to reduce type 2 diabetes in the U.S. through restricting fast-food restaurants in all communities and a targeted increase in rural and suburban supermarkets.