Women, infants, and the food environment: Influences on food security and obesity

Barbara Laraia, Ph.D. and Peggy Bentley, Ph.D.
Department of Nutrition, School of Public Health, The University of North Carolina at Chapel Hill

1. Research objective and policy relevance
   Over the past decade there has been a renewed interest in neighborhood level effects on health. The role that the food environment, and in particular large chain supermarkets, play in providing high diet quality foods to area residents has been recently studied. Although reports of eating trends showed an increase in the proportion of meals eaten away from home, families continue to purchase a majority of their food from supermarkets and grocery stores. Families who spend more of their food dollars on at home foods have been shown to have higher diet quality than families spending more money on away from home foods. Supermarkets continue to demonstrate the greatest variety of food at the lowest cost compared to restaurant food purchases. The presence of grocery stores within a neighborhood has been shown to vary by race; fewer supermarkets have been found in African-American neighborhoods, and in rural vs. urban neighborhoods. As part of an ongoing cohort study to investigate risk factors for postpartum weight retention, we undertook an investigation of the food and physical activity environments in a three county area in central North Carolina.
   

   Overall Specific Aims
   Aim 1: To conduct an ethnographic study of the food environment to identify environmental influences on shopping behaviors, dietary intake, meal patterns and physical activity among postpartum women, infant caregivers and infants.
   Aim 2: To identify policies and social factors which influence food resource and recreation location, and to investigate the directionality of the food environment and dietary intake relationship.

2. Contribution to existing research
   There are many factors that make it difficult to assess the hypothesis that supermarkets have an independent influence on diet quality of area residents. First, there are issues with endogeneity, or omitted variable bias, in that there may be a personal choice influencing both residence and distance to supermarket that is not being measured that might influence diet quality. If such variables could be identified they might strengthen statistical models. Second, although an independent relationship has been found between presence of supermarket and diet, the pathway by which the distance influences diet is not clearly understood. Third, the role that supermarkets play in the lives of individuals is also not understood.



3. Highlights of research methods
   Women were recruited within one year postpartum mainly through Special Supplemental Nutrition Program for Women, Infants and Children (WIC) clinics. Focus group and individual interview participants were organized by race and BMI status. Each focus group interview lasted about 90 minutes and each individual interview lasted 30-45 minutes. In addition, nine interviews were conducted with community leaders including, nutritionists at three WIC clinics, a manager of a convenience store, town planners, representatives from state and national non-profit organizations that promote smart growth and active living, and with state level public health officials. All interviews were audio-taped, transcribed verbatim, coded by the principal investigator and two research assistants, and imported into Nvivo software for data management and to assist with data analysis.



4. Findings
   The open coding process produced 47 themes categorized into eight headings-neighborhood social and physical characteristics, food environment, supermarket environment, physical activity environment, individual resources, individual considerations, individual physical activity issues, and perceived societal and programmatic influences.

   The preliminary findings of postpartum women's perception of their food environment, especially as it pertains to informing a supermarket survey, suggests that more than cost, quality and variety of foods are important in making food purchase decisions. The general atmosphere of supermarkets, specially the cleanliness and customer service, also influences where women shop. Participants in this small qualitative study articulated a strong preference for two of seven commonly mentioned supermarket chains in three central NC counties. Women conveyed a vague sense of "fitting" with their preferred supermarkets. Stores that were perceived as having higher quality food were also perceived as being more expensive. The more expensive stores were places where women were not as comfortable shopping, because they didn't feel welcome or familiar with where items were located, which increased their shopping time. Although most women shopped at large chain supermarkets, they spoke of the quality of the supermarkets being different by neighborhood wealth. Findings also suggested that the characteristics of self-esteem at the individual level might confound the association of neighborhood food resources on diet and weight. Other psychosocial factors such as anxiety and discrimination might be important characteristics to measure, especially among low-income households, that have been previously omitted from models of the neighborhood food environment and diet.

5. Discussion, including implications for food and nutrition assistance policy and/or future research
   Supermarkets may influence shopping and dietary preferences in a variety of ways. Because most households in the central North Carolina sample reported shopping at supermarkets, and did not appear to be dependent on small grocery and convenience stores, the specific mechanisms of how supermarkets influence diet must be explored. Issues of accessibility, affordability, availability, quality, comfort, and frequency of food shopping are potential key elements that might explain how supermarkets influence diet quality and weight gain.

   This study will inform and assist in tailoring a supermarket survey based on the Thrifty Food Plan for the central NC study area. The practical implications of how this study might inform a supermarket audit is to assist with devising an objective measure of the supermarket atmosphere taking into account cleanliness, customer service and overall appeal of the interior of the store. In addition, this study aims to identify mechanisms by which supermarkets may influence individual food choice and purchases in hopes of tailoring interventions to promote optimal nutrition.