WASHINGTON — Contrary to popular belief, recent studies suggest that residing in a “food desert” has a limited impact on the healthfulness of eating.
Questions about the how supermarket accessibility challenges affect the quality of diet were explored in a May article in Amber Waves, published by the Economic Research Service of the U.S. Department of Agriculture.
The U.S.D.A. cited conflicting evidence, with certain studies indicating supermarket density has no impact on intake of fruits and vegetables and others blaming low density and long traveling distances to supermarket for at least a “small negative effect on purchases of fruits and vegetables.”
In its research, the E.R.S. tapped into Nielsen Homescan, a national data set regarding daily food purchases for more than 100,000 households, continuously observed over a year or longer.
Because the data are gathered over the course of year, the researchers are able to track dynamic factors such as “entry/exit of nearby stores.” The U.S.D.A. data show consumers often bypass the nearest supermarket and travel an average of 3.8 miles to the store to buy food.
“E.R.S. researchers examined the purchases of consumers in low-income neighborhoods where a significant number or share of the population live more than 1 mile from a supermarket,” the U.S.D.A. said. “Researchers tracked food purchases as the consumers ventured farther from their home. Limited food store access showed a modest negative effect on the nutritional quality of consumers’ diets. Consumers in low-income/low-access areas purchased 4.3% less fruit, 2.4% less vegetables, and 10.4% less low-fat milk products than consumers not living in such areas. They also purchased 8.6% more red meat and 5.2% more diet drinks than other consumers.”
The researchers theorized that if food access affects consumer food choices, then dietary quality should improve when consumers shop farther from their home. The Nielsen data confirmed that consumers who drive an extra mile to shop improve the quality of their diet quality, but not by much.
“By driving an extra mile to the store, low-access consumers purchased 0.42% more fruits, 0.55% more vegetables, 0.61% more low-fat milk products, and 0.33% less non-diet drinks.”
As a measure of shopping habits in poor neighborhoods, the U.S.D.A. said the Nielsen data may be less than ideal, since these neighborhoods are undersampled, the E.R.S. said.
“These groups are precisely the subpopulations likely to be most affected by limited food access,” the U.S.D.A. said. “If shopping motivations and behaviors differ substantially across these characteristics, then the results obtained from this dataset may not be applicable to all sociodemographic groups. U.S.D.A’s FoodAPS (National Household Food Acquisitions and Purchase Survey) survey was designed to be representative of the entire U.S. population, including SNAP participants and other low-income households. The survey contains rich data on the food retail environment of respondents, enabling researchers to analyze the influence of food store access on food choices.”
For households with severe financial constraints, prices are a primary influence over which foods they purchase. The shoppers who lacked resources were much more cognizant of food prices and less so of food store access, according to the researchers. When both price and demographic factors were considered, the impact of food access was even more insignificant. Price conscientiousness may account for households passing the store closest to them for ones that offer lower prices.
The Amber Waves article examined two recent studies that tested how dietary choices are affected when a new supermarket opens in “food deserts,” areas with poor access to grocery stores. Research from the Rand Corp. found residents in a low-income Philadelphia neighborhood with a new supermarket consumed fewer calories and added less sugars than those in a nearby, demographically similar neighborhood that lacked a supermarket. However, the changes were likely due to other factors, as residents who used the new store had similar diets to those who did not. Additionally, fruit and vegetable consumption actually decreased in both neighborhoods, the researchers said.
The results may be attributed to elements of store choice besides proximity. When a new store is built, people will shop there only if it offers the products and prices of which shoppers approve. The store must also compete with existing stores that are farther away but close enough to attract customers. Still, even if the new stores do attract most of the neighborhood households, improvements in diet quality are not guaranteed, the researchers said.
In the second experiment conducted in Pittsburgh, 68% of residents in the new-store neighborhood utilized their new grocery store, but their diet quality was no better than their neighbors who continued to shop at their usual store.
The results suggest that improving healthy food access alone will not suffice in attempting to impact consumer diets or majorly reduce diet-related diseases. Effective approaches toward encouraging healthier choices may include lowering transportation costs, subsidizing fruits and vegetables, and running educational campaigns, the researchers said.
High product prices coupled with limited incomes, limited consumer knowledge about nutrition, and various food predilections are perhaps more central in determining what foods shoppers will purchase than are poor access to stores.