SEARCH

SEARCH BY CITATION

TO THE EDITOR:

Dubowitz et al. provide the latest data linking select aspects of local food environments to select obesity-related health measures (1). The authors' lengthy limitations section highlights some of the measurement challenges to conducting this type of research. If future research is to identify the most promising strategies to improve food environments, support healthy eating, and prevent obesity, then the field needs to move beyond some common measurement limitations of early studies.

First, the use of unvalidated business-list data is precarious. Although such data were convenient and efficient for establishing foundational associations in early studies, they are less than ideal for the field moving forward. For example, based on detailed ground observations of all food sources from >150 Bronx streets, research in our group has shown the business list used by Dubowitz et al to have a positive predictive value below 50% overall, and a sensitivity for grocery stores of only about 25% (manuscript under preparation). Other researchers have reported similar findings (and the business list having a sensitivity of <10% for fast food) (2). More-accurate food-environment data, verified on-the-ground, are needed.

Beyond issues of accuracy, the concern with reliance on business lists is two-fold: [1] it inappropriately groups all food sources of a certain type (e.g., as if every supermarket were the same as every other supermarket in terms of selection and quality of products, when empirically this is not the case (3)), [2] it generally restricts focus to a limited range of food outlets (e.g., “fast-food restaurants,” “grocery stores and supermarkets” (1)). Studies using business-lists necessarily neglect impermanent sources of food that may be relevant, like street vendors (4, 5) and farmers' markets (6, 7). They also routinely neglect–more due to investigator decision as opposed to data deficiency a range of other potentially relevant food sources like pharmacies, gas stations, hotels, salons, general merchandisers, clothing outlets, book stores, and other retail selling food and drink (8). More-complete availability measures, that include generally neglected food sources, are needed.

A separate issue concerns definitions of food-source proximity. While studies like that of Dubowtiz et al commonly use radial “buffers” (1), such buffers ignore how people travel in their environments and their barriers to transit. For example, one-way streets and divided highways have different implications for motorists than for pedestrians, and research that fails to consider how people actually access food may miss relevant associations (9). An alternative approach to radial buffers, favored by geographers, is to measure accessibility along existing street networks for walking or driving (10). More-precise accessibility measures, that consider how people travel to get food, are needed.

Dubowitz et al. conclude that their findings support restricting the development of fast-food outlets and attracting grocery stores (1). Given measurement limitations, including those above, we do not find strong support for this conclusion. Perhaps greater benefit would come from promoting famers' markets and produce carts … or from restricting the sale of unhealthy foods at salons and pharmacies (but maybe only for those along walking routes and not for those accessed by motor vehicles). To investigate such possibilities and understand different options for intervention, it is time for the field to move beyond the limitations of early research, making use of more accurate, complete, and precise measures.

References

  1. Top of page
  • 1
    Dubowitz T, Ghosh-Dastidar M, Eibner C, et al. The women's health initiative: the food environment, neighborhood socioeconomic status, bmi, and blood pressure. Obesity (Silver Spring) 2012; 20: 862871.
  • 2
    Powell LM, Han E, Zenk SN, et al. Field validation of secondary commercial data sources on the retail food outlet environment in the U.S. Health Place 2011; 17: 11221131.
  • 3
    Farley TA, Rice J, Bodor JN, Cohen DA, Bluthenthal RN, Rose D. Measuring the food environment: shelf space of fruits, vegetables, and snack foods in stores. J Urban Health 2009; 86: 672682.
  • 4
    Lucan SC, Maroko A, Shanker R, Jordan WB. Green carts (mobile produce vendors) in the bronx-optimally positioned to meet neighborhood fruit-and-vegetable needs? J Urban Health 2011; 88: 977981.
  • 5
    Tester JM, Yen IH, Laraia B. Mobile food vending and the after-school food environment. Am J Prev Med 2010; 38: 7073.
  • 6
    Jilcott SB, Keyserling T, Crawford T, McGuirt JT, Ammerman AS. Examining associations among obesity and per capita farmers' markets, grocery stores/supermarkets, and supercenters in US counties. J Am Diet Assoc 2011; 111: 567572.
  • 7
    Park Y, Quinn J, Florez K, Jacobson J, Neckerman K, Rundle A. Hispanic immigrant women's perspective on healthy foods and the New York City retail food environment: a mixed-method study. Soc Sci Med 2011; 73: 1321.
  • 8
    Farley TA, Baker ET, Futrell L, Rice JC. The ubiquity of energy-dense snack foods: a national multicity study. Am J Public Health 2010; 100: 306311.
  • 9
    Jilcott SB, Wade S, McGuirt JT, Wu Q, Lazorick S, Moore JB. The association between the food environment and weight status among eastern North Carolina youth. Public Health Nutr 2011; 14: 16101617.
  • 10
    Apparicio P, Abdelmajid M, Riva M, Shearmur R. Comparing alternative approaches to measuring the geographical accessibility of urban health services: distance types and aggregation-error issues. Int J Health Geogr 2008; 7: 7.