Dhruv Khullar, M.D., M.P.P., (@DhruvKhullar) is a physician and assistant professor of Medicine and Healthcare Policy at Weill Cornell, and director of policy dissemination at the Physicians Foundation Center for Physician Practice and Leadership.
For years, public health advocates have argued that food deserts—neighborhoods without grocery stores or other fresh food vendors—contribute to a disproportionate burden of obesity and chronic disease among low-income individuals. Ready access to fresh, healthy food intuitively seems important for supporting a healthful diet.
But recent evidence contests the idea that watering America’s food deserts will solve its obesity crisis.
Compared with high-income individuals, poor Americans tend to have diets higher in sugar, fat and processed foods and lower in fiber, fruits and vegetables. This “nutritional inequality” is a contributor to the large income-based health disparities in the U.S., and is thought to be due in part to more limited access to healthy food. Over the years, the federal government has spent hundreds of millions of dollars to incentivize supermarkets to move to underserved areas.
But does introducing a supermarket into a food desert change the grocery habits of nearby residents? Not so much, according to a recent study that examined thousands of new supermarket openings across the country. Researchers found that less than one-tenth of the nutritional inequality between high- and low-income households could be explained by the availability of healthy foods. The other 90% was due to differences in demand. These results are supported by other recent studies suggesting that, by itself, access to healthy food is unlikely to meaningfully change what people buy and eat.
In a way, these findings should not be surprising. What we choose to eat is the result of a complex interaction among our culture, friends, tastes, education and life experiences. It is also, of course, informed by practical considerations like convenience and price. High-income households are willing to pay nearly triple what low-income households are for healthy food, and one study found that, calorie-for-calorie, nutritious food can cost 10 times as much as junk food.
None of this is to suggest we shouldn’t be concerned about eliminating food deserts.
Ensuring that all Americans can access healthy food if they choose is a moral imperative. It’s the right thing to do—regardless of whether it moves the needle on obesity or medical costs.
It is also important to recognize that cultural change takes time. Food preferences form over decades—sometimes generations—and it’s unrealistic to expect they will shift overnight because Whole Foods just opened down the street. Still, the point is that access to fresh food is a necessary—though, on its own, insufficient—part of long-term strategy for reducing rates of obesity, diabetes and other chronic diseases. Nutrition education, public health programs and changes to agricultural subsidies will also play a role.
Finally, while fixing food deserts may not make people’s diets healthier, there is evidence to suggest that a new supermarket can have other positive effects. Perhaps most important is a reduction in food insecurity for those living in the area. Food insecurity—not having reliable access to enough food—is linked to a host of adverse health outcomes, including depression, anxiety, chronic disease and birth defects. A recent study found that a new supermarket in a low-income neighborhood improved the health and economic well-being of nearby residents, including a 12% reduction in food insecurity and a similar decline in the need for the Supplemental Nutrition Assistance Program (previously known as food stamps). Other research has also found meaningful improvements in rates of food insecurity, especially among low-income children. Reducing food insecurity, particularly childhood hunger, is a critical public health goal in its own right—and also important for reducing preventable health-care utilization and costs.
Food deserts, then, don’t seem to cause obesity. But eradicating food deserts may still be part of a broader shift toward greater food security today and a healthier food environment and population in the long run.