Policy makers want to bring grocery stores and other healthy-food retailers to underserved areas. But research by New York University’s Hunt Allcott, Stanford’s Rebecca Diamond, and Chicago Booth’s Jean-Pierre Dubé finds that even when families have access to healthier foods, they don’t necessarily buy them. The researchers worked with data, from the Nielsen Datasets at Chicago Booth’s Kilts Center for Marketing, that include grocery purchases by some 60,000 US households per year and grocery sales at about 35,000 stores nationwide from 2004 to 2015. The evidence suggests that preferences for healthy food, rather than an adequate supply of it, may be driving the nutrition gap between higher- and lower-income households. The findings suggest that policies aimed at nutrition education could be more effective than subsidies and grants meant to encourage building more supermarkets in food deserts.

The relationship between nutrition and income

Lower-income households buy more foods that are sugary and less that are notably healthy, such as whole-grain breads, compared to households with higher incomes. The researchers’ health index, an overall measure of household groceries’ nutrition content, shows that not only did higher-income groups make healthier purchases, but they also improved their health scores at a greater rate in recent years.

People in food deserts still go to supermarkets

Households in US zip codes without supermarkets travel farther to do their grocery shopping, despite arguments by some policy makers and advocates that people in these areas rely on less-ideal options such as convenience stores.

Why lower-income households buy less-healthy groceries

Demand-side factors rather than supply-side factors explain most of the nutrition gap between lower- and higher-income households. A counterfactual analysis finds that if everyone had the same access to healthy food, with the same prices, the nutrition gap would narrow by 9 percent. But if everyone shared the same food and nutrient preferences, the gap would shrink by 91 percent.