The food desert concept was first introduced in the United Kingdom in the early 1990’s to examine disparities in food pricing and to describe geographical areas with limited access to retail grocery stores . A food desert is a food environment unsupportive of health; it is defined by barriers which restrict access to healthy foods. Barriers may include lack of access to food retailers, availability of nutritious foods, or affordability of foods.
Research has defined food deserts quantitatively or by neighborhood characteristics such as economic and social barriers.
In 1996, a British Low Income Project Team defined food deserts as “areas of relative exclusion where people experience physical and economic barriers to accessing healthy foods” (Reising and Hobbiss, 2000). The exclusion refers to the shift of food retailers away from urban areas, an outcome of urban sprawl and segregation.
A definition by Furey et al., reflects these characteristics, describing an area where “high competition from large chain supermarkets has created a void” (Furey et al 2001). Cummings and Macintyre define a food desert as a “poor urban area, where residents cannot buy affordable, healthy food” (2002). Recently, the Mari Gallagher Research and Consulting Group has defined “food deserts” as large isolated geographic areas that cluster and are lacking or remain distant from mainstream grocery stores. White House representatives of the Let’s Move campaign have referenced the 2008 Farm Bill definition as “an area in the United States with limited access to affordable and nutritious foods, particularly in a low-income area” (USDA). Despite differences in terminology, most research in the United States supports the hypothesis that on the neighborhood level, there are disparities in the retail food environment (Ford).
History and Theories for Development
Before the 1950’s, the food landscape of rural and urban areas consisted of local, small businesses and supermarkets. In recent decades, many traditional food-retailing firms have become larger and the total number of stores has decreased. “Land-use policies that facilitate development of predominately wealthy and white suburban neighborhoods” have altered the distribution of food stores, as larger supermarkets have migrated alongside residents to suburban areas (Morland, 2002). As a result, the food supply within inner-cities includes less variety, denying some urban residents the benefits of healthy foods at affordable prices (Yeh, 2006). Remaining food retailers in inner-cities are gas stations, convenience stores, and liquor stores. A diet based on foods from these locations consists primarily of processed foods high in calories, sugars, salt, fat, and artificial ingredients. Health disparities related to food access and consumption are associated with residential segregation, low incomes, and neighborhood deprivation.
Access to Quality Food
The main factor used to classify a community as a food desert is distance from nutritional food retailers. There is no standard for “inadequate” access or “adequate” access to foods. Access to food is calculated by distance of consumer residence to nearest supermarket or grocery store. Distance is measured from centroid of area an area (by zip code, census tract, or block) to nearest supermarket or grocery store. Standards of access and methods of measurement vary among researchers to determine food deserts. Research suggests food deserts exist if consumer residence is one to ten miles away from the nearest supermarket. Other measurements include “urban areas with 10 or fewer stores with no more than 20 employers” (Hendrickson et al 2006). The USDA’s Thrifty Food Plan aims to standardize the methods of assessment for the availability and price of foods in stores.
Residents of food desert areas have no alternative but to utilize private cars, travel several miles on foot, or use public transit to gain access to healthy food. Consumers without cars are dependent on food sources in their closest proximity. Ownership and access to a vehicle may be the best marker for access regardless of SES status. A study by Inagami reveals that the distance traveled to food stores is an independent predictor of BMI. The problem increases in rural food desert areas, where closing the distance to nutritional food access is impossible on foot.
Researchers have determined that distance to food is also psychological. The physical distance from fresh foods has determines eating behaviors and preferences for palatable, processed foods. To create a healthy relationship with food, researchers recommend creating a direct connection between fresh produce and consumer. Examples of this include urban farm programs and incorporating healthy foods in schools.
Research indicates that low-income households shop where food prices are lower, and generally cannot afford healthy foods. Compared with residents of higher-income neighborhoods, low SES individuals generally have diets higher in meat and processed foods with a low intake of fruits and vegetables (Yeh, 2006). It has been suggested that people of low socioeconomic status ultimately spend up to 37% more on their food purchases, due to smaller weekly food budgets and poorly stocked grocery stores (Morland, 2002).
Fringe food retailers in food deserts can have a 30-60% markup on prices, provide a limited selection of products and a dominant marketing of processed foods. A comparison of prices consumers pay for similar foods purchased at a different outlet determine disparities in real food prices. Nutritional foods such as whole grain products and fresh fruits and vegetables are more expensive than high calorie junk foods. “Energy-dense [junk foods] cost on average $1.76 per 1,000 calories, compared with $18.16 per 1,000 calories for low-energy but nutritious foods”.
Racial, Ethnic, and Socioeconomic Disparities
Health disparities and adverse health outcomes are associated with residential segregation, poverty and neighborhood deprivation.
In a study on urban food environments, participants described the lack of supermarkets as both a “practical impediment to healthy food purchase and a symbol of their neighborhoods’ social and economic struggles” (Canuscio, 2010). Within cities, there are more than three times as many supermarkets in wealthier neighborhoods compared with poorer areas (Yeh, 2006). Residents in low-income urban areas are often “forced to depend on small stores with limited selections of foods at substantially higher prices” (Morland, 2002).
Research has found parallel trends between high rates of obesity and individuals of low SES and non-white ethnicity, particularly in the case of women. (Robert et al. & Schulz et al). Research by Morland et al, found that areas with a majority of convenience stores have a higher prevalence of overweight and obese individuals, compared to areas with only supermarkets (Morland 42). Fast food restaurants are disproportionately placed in low-income and minority neighborhoods, and are often the closest and cheapest food options (USDA). “People living in the poorest SES areas have 2.5 times the exposure to fast-food restaurants as those living in the wealthiest areas” (Yeh, 2006). The lack of adequate food sources and limited transportation available to low-income communities are contributing factors to malnutrition among those living in low SES neighborhoods (Morland, 2002).
Research has documented inequalities of access to supermarkets in urban city areas, and found a difference in access to supermarkets in poor vs non-poor areas. A study by Baker et al, found that mixed-race areas were significantly less likely to have access to foods that adhere to a healthy diet compared to predominantly white, high income areas (Ford). Research by Mari Gallagher has found that African Americans are farther from healthy foods than other racial groups. (Gallager). Morland’s study of food-frequency data in the Atherosclerosis Risk in Communities (ARIC) study revealed that dominantly white populations had five times more supermarkets than neighborhoods with a dominantly non-white population. African Americans who lived in the same census tract with access to a supermarket were more likely to meet dietary guidelines for fruit and vegetable consumption. For each additional supermarket, an increase of 32% in fruit and vegetable intake was found. (Morland et al 42).
Prevalence of obesity is generally higher in rural areas as compared to urban areas. Socioeconomic factors inhibit access to private cars as well as limited reliable public transportation.
The USDA released an extensive report to Congress in 2009 as a request to reform the Food, Conservation, and Energy Act of 2008. The study outlines a list of recommendations for addressing access issues in food deserts (USDA).
Initial research on food deserts explored the impact of retail flight from the urban core (Ford). Studies of urban and rural food environments reveal significant potential for evidence-based interventions and policies to combat the growing obesity epidemic, and to decrease some health disparities. “Multilevel, mixed methods studies offer the potential to provide a more complete picture of the direct and perceived environmental influences on healthy behaviors” (Ford and 71).
But the study of food deserts requires further research, including longitudinal studies of food environments, to support associations with obesity and to support neighborhood interventions. Longitudinal studies “permit temporal associations” between exposure to nutritious food and obesity (Ford). They also provide historical data on grocery store location, nutritional environments, and data associated with life-course exposure to food (Ford).
Future research is required to overcome the barriers facing residents of food deserts, including retail trends and location of supermarkets, in order that food retailers and city planners may develop multilevel interventions to address barriers to health at the individual and environmental level. Studies which examine geographic differences in the access and availability of food, as well as nutritional quality of food, provide information for public health to explain disparities.
More recent studies have shown some correlations between food availability and health, including a 2010 study that correlated distance from supermarkets with increases in body mass index (see DataHaven document, below).
Casual inferences on the relationships among food environment, food choices, and obesity are limited by observational and cross-sectional research methods (Ford).
Access is not the only determinant to healthy eating. There are many environmental determinants that predict a positive outcome in healthy eating for residents of current food desert areas, such as transportation, culture, social capital, and food price. A criticism of current research on food access and obesity assumes a “simplistic deprivation effect associated with poor-quality food environments” (Ford).