Convenience store in San Antonio, Texas. Such stores are more common in "food deserts" -- communities with concentrations of low-income residents and no nearby grocery stores.

A new study of the food-buying habits of Americans who live in “food deserts” finds little evidence to support the assumption that getting healthier food on the shelves in low-income communities will lead to residents eating a healthier diet.

Researchers using commercially available consumer data found that people’s food-purchase decisions didn’t improve significantly when they shopped at stores that had healthier food on the shelves.

“Living in [an area with low incomes and limited access to healthy foods] has only a modest negative effect on the healthfulness of food purchases – a difference too small to explain much of the national disparities in diet quality and obesity,” wrote the economists who conducted the study, Ilya Rahkovsky and Samantha Snyder with the U.S. Department of Agriculture’s Economic Research Service.

But an advocate who supported the creation of federal financing programs to establish better food outlets in poor, underserved communities says one study doesn’t undermine years of research showing that better access to healthy foods is a necessary ingredient in improving nutrition.

“Every few year there’s a study like this that is trying to measure the immediate impact of these types of community initiatives,” said Allison Hagey, who works in the health-equity and food-access program at PolicyLink. “Often the focus is on one single measurement and misses the bigger picture of what it means to have a healthy community.”

The study used data from the 2010 Nielsen Homescan Panel Survey, which tracks consumers’ purchases of individual items, including where the purchase was made. Researchers compared the shopping behavior of residents of low-income, low-food-access communities when they shopped in their own neighborhoods and when they shopped outside their neighborhood.

The researchers’ theory was that if the availability of nutritious food was an important factor in dietary decisions, consumers would purchase significantly greater amounts of healthy foods when they were outside their immediate neighborhoods – which lacked healthy food choices. But the study found that when consumers from food deserts had access to better foods, their shopping patterns changed only slightly.

Other factors like the resident’s income or previous purchase decisions were much more influential on shopping choices than access alone. “Demographics trumps access” in influencing consumers’ food choices, Rahkovsky said.

Hagey said the findings did not contradict advocates’ understanding of what helps create healthier communities.

“Having access to a place to purchase more nutritious food is not a silver bullet,” she said. “It takes a lot of other kinds of support within a community to ensure that people are making good nutrition choices. But you have to have the choice that access provides before people make better decisions.”

PolicyLink was part of a coalition of groups that successfully advocated for the 2014 Healthy Food Financing Initiative, which provides $125 million in capital over five years to community-based initiatives to establish grocery stores in food deserts. The financing program is run through the Department of Agriculture in cooperation with Health and Human Services and the Treasury Department.

Food deserts, also known as “low-income, low-access” communities or LILAs, are areas with a high concentration of poor people located at least a mile from the nearest full-service grocery store. In rural areas, communities must be low income and farther than 10 miles from the nearest grocery store to qualify as low-income, low-access.

Food deserts, or LILAs, have a greater proportion of fast-food restaurants and convenience stores than other communities. They lack full-service food markets, which typically have more fresh vegetables, fruits, and other healthy foods.

Researchers agree that people who live in low-income, low-access communities – both rural and urban – are more likely to have obesity-related diseases like type 2 diabetes and heart disease. The question is what causes these residents to have poorer health.

Click the map to explore food-desert data at the USDA Economic Research Service. (Map: USDA ERS)

The USDA Healthy Food Financing Initiative says that lack of access to healthy food choices “contributes to a poor diet and can lead to higher levels of obesity and other diet-related illness, such as diabetes and heart disease.”

But the new study implies that other factors like income are more important in determining who will suffer from poor health.

The Economic Research Study researchers said there were important limitations on their research. The data they used “undersamples” poor people. That means the survey doesn’t capture enough data from low-income families to match the proportion of poor people in the general U.S. population. The limitation is especially true for the poorest residents of a community, Rahkovsky said.

Second, the study considered only food purchased in grocery stores for preparation at home. It did not include restaurant purchases.

Among other findings in the study were the following:

  • The price of food between low-access and other neighborhoods wasn’t significantly different.
  • Residents of low-access areas, no matter where they shopped, bought 4.5% less fruit, 2.7% less vegetables, and nearly 11 % less low-fat milk products.
  • Most residents of low-income, low-access communities travel farther from home to shop for food.
  • Low-income, low-access shoppers who travel outside their communities to shop tend to purchase more fruits, vegetables, fish, and poultry than residents who shopped in their low-income neighborhoods. But “these effects are small and they cannot explain large nutritional disparities observed in the population,” the report says.
  • Low incomes explained more of the difference in shopping choices than did the lack of local healthy-food choices.

Hagey of Policylink said food access is a hot research topic. There have been 160 studies on food access in recent years, she said, and most of those studies find a relationship between access and healthy diets.

“But the good thing about [contradictory studies] it is that we get to remind people that access to nutritious food is still an important issue, that are there are more than 23 million people people out there who don’t have convenient access to healthy food,” she said.

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