terms of a dummy variable that takes a value of 1 if any of the food consumed was purchased in a supermarket, and 0 if all foods were obtained from traditional sources. All estimates are net effects of supermarkets after controlling for confounding factors, such as income, age, education, and physical activity levels, among others.
Table 2. Effects of supermarket shopping on adults’ health
While supermarket shopping significantly reduces the amount of daily energy from unprocessed staples (–112 kcal) and fresh fruits and vegetables (–124 kcal) consumed by adults, it increases the consumption of meat and fish (+24 kcal), dairy and eggs (+9 kcal), and vegetable oils (+60 kcal). Furthermore, supermarket shopping increases the share of energy from highly processed foods by 3 percentage points. Demmler et al. [21] clearly showed that supermarkets contribute to dietary changes towards more animal-source products and foods with higher energy density and higher processing levels. At the same time, supermarkets reduce the consumption of unprocessed foods and fresh fruits and vegetables.
Supermarkets also have significant effects on adults’ nutritional outcomes in Kenya. Demmler et al. [21] found robust evidence that shopping in supermarkets significantly increases adult BMI by 0.64 and significantly increases the likelihood of being overweight/obese by 7 percentage points (Table 1). While the effects on BMI estimated with the panel data are somewhat smaller than those estimated in earlier studies with cross-sectional data [14, 17, 22], they are more robust and reliable as they better control for possible endogeneity bias.
Fig. 1. Prevalence of child and adolescent stunting and underweight depending on household shopping behavior. *** Difference between children in households shopping and not shopping in supermarkets significant at the 1% level. Authors’ presentation based on data from Debela et al. [24].
Supermarket Effects on Adults’ Health
Table 2 shows the effects of supermarket shopping on adults’ fasting blood glucose (FBG), the likelihood of being pre-diabetic, and the likelihood of suffering from the metabolic syndrome. These results are based on cross-sectional health data collected in 2015 from the same adults in medium-sized towns in central Kenya. Demmler et al. [22] used instrumental variable models to control for endogeneity bias. The regression results suggest that supermarket shopping has a significant effect on all three health outcomes; it significantly increases the level of FBG by 0.3 mmol/L and increases the likelihood of suffering from pre-diabetes and the metabolic syndrome by 16 and 7 percentage points, respectively.
While Demmler et al. [22] found no significant effects of supermarket shopping on blood pressure or being hypertensive, the results showed a clear tendency that supermarket shopping does not only affect diets and the nutritional status of adults, but also health outcomes. While nutrition-related NCDs like diabetes and hypertension are mainly channeled through higher levels of BMI, Demmler et al. [22] also suggest that health outcomes might be directly affected through dietary changes. Since diets rich in bioactive compounds, micronutrients, and fiber are shown to be beneficial in order to prevent NCDs [23], a decrease in the consumption of fresh fruits and vegetables and unprocessed staples, as shown in Kenya [21], is likely to affect health outcomes directly.
Supermarket Effects on Children and Adolescents
While the effects of supermarket shopping on adult nutrition and health are negative and undesirable (higher rates of overweight/obesity and NCDs), the implications for children are quite different. Focusing on the same households in central Kenya as surveyed by Demmler et al. [21, 22], Debela et al. [24] used panel data from children/adolescents between 2 and 18 years of age. Figure 1 depicts descriptive results showing that stunting and underweight are prevalent in 15 and 7% of all children in the study area, respectively. Furthermore, there is a significantly lower prevalence of stunting in children/adolescents from households that obtain foods from supermarkets (10%) than in children from households that obtain foods solely from traditional sources (21%). Running panel data regression models, Debela et al. [24] confirmed that supermarket shopping has a significantly positive effect on child height, increasing height-for-age Z-scores by 0.34, even after controlling for confounding factors like household expenditures, sanitary aspects, age of the child, and mother’s attributes (body height, education, and age). Supermarket shopping also increases child weight-for-age Z-scores, but the effect is much smaller and no significant effect on child overweight was found [24].
Fig. 2. Comparison of mean FVS (a) and DDS (b) for households shopping and not shopping in supermarkets. FVS based on food item count; DDS based on 12 food groups. Less healthy food items/groups excluded for FVS 2/DDS 2 are fats, oils, sugar, sweets, and spices. *** Difference between households shopping and not shopping in supermarkets significant at the 1% level. Authors’ presentation based on data from Debela et al. [24].
The nutritional improvements in children/adolescents through supermarket shopping seem to be mainly caused by increased dietary diversity [24]. Households that buy food in supermarkets have significantly higher food variety scores (FVS) and dietary diversity scores (DDS) than households that obtain all foods from traditional sources (Fig. 2). One concern could be that supermarket shopping would especially increase the consumption of unhealthy food items, which could drive up FVS and DDS without necessarily increasing dietary quality and micronutrient supply. However, significant differences also remain after excluding the food items/groups that are considered less healthy (Fig. 2). Even though supermarket shoppers consume more processed foods, their diets seem to be more protein and micronutrient rich, especially through higher and more regular consumption of animal-source foods [24]. These additional nutrients are beneficial for child growth, especially in situations where child stunting is still an issue.
Interventions Regarding Supermarkets
While there is a good body of literature on interventions regarding the food environment
