Associations between access to farmers’ markets and supermarkets, shopping patterns, fruit and vegetable consumption and health indicators among women of reproductive age in eastern North Carolina, USA

Improved access to food venues such as farmers’ markets and supermarkets is commonly proposed as a strategy to address the obesity epidemic, as studies have shown that those who live closer to farmers’ markets(1,2) and supermarkets (3,4) generally have lower BMI than those who live further from such food venues(5,6). The underlying assumption of such studies is that greater access to such food venues may lead to purchase and consumption of fresh produce. For example, Yoo et al.(7) found that those who shop more frequently at supermarkets tended to have healthier diets when compared with those who shop less frequently at supermarkets. In a North Carolina-based study, we found that more frequent shopping at supermarkets was associated with healthier purchases among Supplemental Nutrition Assistance Program participants, when compared with those shopping at supermarkets less frequently(8). Greater knowledge about associations between access to food venues, shopping frequency and food purchases is needed to inform future efforts to increase access to healthy foods. Furthermore, much of the research regarding the food environment has involved objective measures of the food environment via Geographical Information Systems (GIS)(1–4), while some posit that perceptions of the food environment have a greater impact on shopping choices/behaviours than objective measures(9–11). In particular, an understudied aspect of food venue access, particularly important for quantifying access to farmers’ markets, is ‘accommodation’, which includes the business hours a particular venue is open, seasonal schedules and other factors that may affect both perceived and objectively measured access to the food venue(12). One group of researchers incorporated business hours to objectively measure food venue access, and found that those who consumed fruit more frequently had greater access to greengrocers (venues selling fruits and vegetables) that had longer hours of operation(13). Among Hispanic women in New York City, the presence of a farmers’ market in women’s neighbourhoods was associated with greater fruit and vegetable consumption(14). Another group examined seasonality and access to farmers’ markets in New York State and found that higher-poverty census block groups had greater objectively measured access to produce markets during the summer months, but less access to such markets during the spring and winter months, when compared with all block groups(15). In the field of geography, researchers have used time and distance functions to create accessibility indices(16,17), yet these techniques have not been widely used in the field of public health. This approach lends itself to exploring how objective space and time accessibility measures are associated with use of farmers’ markets, fruit and vegetable consumption and health. Learning about individuals’ food shopping patterns and the locations where they shop will help facilitate more accurate assessments of true food environment exposures (18,19). Not much is known about shopping patterns and frequencies, the distance individuals are willing to travel to purchase foods(18,19). One study found that the mean distance travelled to supermarkets was 7·5km (4·67 miles)(19), while a recent review of the literature indicated that individuals travel 9·7–27·4 km (6–17 miles) to farmers’ markets(20). It is unknown whether individuals tend to shop at the food venues closest to their home or whether they travel past the closest venue to shop at another venue, perhaps due to more competitive prices, wider selection or other factors. Such knowledge is important because, in a previous study, those who travelled further to the grocery store had higher BMI(21). Determining individuals’ ‘food activity spaces’, or the geographic locations and variety of food venues at which individuals shop, is also important for future epidemiological studies of associations between food access and health. Therefore, the purpose of the current study was to examine associations between access to food venues (farmers’ markets and supermarkets), shopping patterns and health indicators among low-income women of reproductive age in eastern North Carolina. It is important to learn about such women’s access to and use of healthy food venues, as low-income populations may be less likely to shop at farmers’ markets than their higher-income counterparts(20). Low-income women of reproductive age are also at increased risk of chronic disease(22) and shopping at healthy food venues may help ameliorate this risk. In one study of health behaviours among a nationally representative sample of women of reproductive age, women with a history of gestational diabetes and with children in the household had significantly lower odds of consuming at least five servings of fruits and vegetables daily, compared with those with a history of gestational diabetes not living with children(23). In the current study, we examined associations between objectively measured access to food venues (farmers’ markets and supermarkets), frequency of shopping at venues and health indicators (e.g. fruit and vegetable consumption, BMI and blood pressure). Objectively measured access included: (i) distance to the closest food venue to the residential location; (ii) mean distance travelled to the food venues where women reported shopping (visited food venue); and (iii) a novel indicator of space and time accessibility to farmers’ markets, incorporating distance, seasonality and business hours. We hypothesized that better access to supermarkets and farmers’ markets would be associated with more frequent shopping and more favourable health indicators. As perceived access to food venues may be more important than objectively measured access(9–11), we also examined the association between perceived and objectively measured access. Finally, we examined the mean distance travelled to food venues and further explored whether the mean distance travelled to food venues varied by rural/urban residence.