This is a first in a series of short reports that summarize recent scientific studies of key food policy questions.
Do more supermarkets in a neighborhood make healthier food more available? Are people living in neighborhoods with fewer supermarkets at higher risk of obesity, diabetes and other diet-related diseases? A recent international review and a study in New York City, cited at the end of this report, provide evidence on these questions. A few cautions are in order, however. First, the evidence that supermarkets provide a health advantage seems stronger for the United States than for countries such as the United Kingdom, Australia, and Canada. Some observers speculate that the high degree of residential segregation in the United States and the heavy reliance on automobiles(except in cities like New York) make local supermarkets more important for low-income neighborhoods here than elsewhere. Second, defining neighborhood is not simple. How close does a supermarket have to be to increase access? Most studies use a fixed distance(often half a mile or a ten minute walk from the house) but this doesn’t always account for barriers such as big highways or a dangerous neighborhood. Third, only few studies have looked at the actual quality of food inside a supermarket, assuming instead that all supermarkets offered different choices than, say, small grocery stores or other types of retail outlets. In fact, the quality of supermarkets varies considerably, often by the racial/ethnic and socioeconomic characteristics of the population served.
With these cautions, the US literature seems to provide solid evidence that more supermarkets do make healthier food more available. In a recent review by Black et al, 10 of 24 US studies showed that better access to supermarkets or green grocers was associated with healthier dietary behavior. However, 11 other studies showed no such association.
What does seem clear is that poor and Black and Latino neighborhoods have fewer supermarkets than better off communities. Black et al.’s review notes that four review articles of US studies show that low income and ethnic communities have fewer supermarkets per capita and farther distances to travel to these stores than better off ones.
The evidence most relevant to New York City comes from a recent study by Viola et al. These researchers looked at density of supermarkets in New York City neighborhoods and assessed its relationships with overweight and obesity. They found a significant negative relationship between supermarket density and overweight and obesity, that is neighborhoods with more supermarkets had lower rates of obesity and overweight. Their study showed that only half of New York City residents have a supermarket that is easily accessible, defined as within a quarter mile of their residence. They conclude that “in an average postal code (i.e., zip code) with 50,000 people, increasing access by one supermarket within a quarter mile of where residents live would result in approximately 43 fewer overweight people and 53 fewer obese people.” They recommend policy makers “increase their focus on improving access to healthy food choices.”
Viola D, Arno PS, Maroko AR, Schecter CB, Sohler N, Rundle A, Neckerman KM, Maantay J. Overweight and obesity: Can we reconcile evidence about supermarkets and fast food retailers for public health policy? Journal of Public Health Policy 2013;3:424-438.
Black C, Moon G, Baird J. Dietary inequalities: what is the evidence of the effect of the neighborhood food environment? Health and Place, http://dx.doi.org/10.1016/j.