Real-life experiments in supermarkets to encourage healthy dietary-related behaviours: opportunities, challenges and lessons learned.

BACKGROUND: Supermarkets are the primary source of food for many people yet their full potential as a setting to encourage healthy dietary-related behaviours remains underutilised. Sharing the experiences from research groups who have worked with supermarket chains to evaluate strategies that promote healthy eating could improve the efficiency of building such relationships and enhance the design quality of future research studies. METHODS: A collective case study approach was used to synthesise experiences of engaging and sustaining research collaborations with national supermarket chains to test the effectiveness of health-focused in-store interventions. The collective narrative covers studies conducted in three high-income countries: Australia, the Netherlands and the United Kingdom. RESULTS: We have distilled our experiences and lessons learned into six recommendations for conducting high quality public health research with commercial supermarket chains. These include: (i) using personal contacts, knowledge of supermarket activities and engaging executive management to establish a partnership and allowing time to build trust; (ii) using scientifically robust study designs with appropriate sample size calculations; (iii) formalising data exchange arrangements and allocating adequate resource for data extraction and re-categorisation; (iv) assessing effects at individual/households level where possible; (v) designing a mixed-methods process evaluation to measure intervention fidelity, dose and unintended consequences; and (vi) ensuring scientific independence through formal contract agreements. CONCLUSIONS: Our collective experiences of working in non-financial partnerships with national supermarket chains could be useful for other research groups looking to develop and implement supermarket studies in an efficient manner. Further evidence from real-life supermarket interventions is necessary to identify sustainable strategies that can improve population diet and maintain necessary commercial outcomes.

How healthy and processed are foods and drinks promoted in supermarket sales flyers? A cross-sectional study in the Netherlands.

OBJECTIVE: To investigate to what extent promotions in Dutch supermarket sales flyers contribute to a healthy diet and whether there are differences between supermarket types. DESIGN: A cross-sectional study investigating promotions on foods and beverages (n 7825) in supermarket sales flyers from thirteen Dutch supermarket chains (8-week period), including ten traditional, two discount and one organic supermarket chain(s). Promoted products were categorised by food group (e.g. bread), contribution to a healthy diet (yes/no), degree of processing (e.g. ultra-processed), promotion type (temporary reduction in price, volume-based promotions or advertised only) and percentage discount of price promotions. Differences between supermarket chains in the degree of healthiness and processing of products and the types of price promotions were investigated. RESULTS: In total, 70·7 % of all promoted products in supermarket sales flyers did not contribute to a healthy diet and 56·6 % was ultra-processed. The average discount on less healthy products (28·7 %) was similar to that of healthy products (28·9 %). Less healthy products were more frequently promoted via volume-based promotions than healthy products (37·6 % v. 25·4 %, P < 0·001). Discount supermarket chains promoted less healthy (80·3 %) and ultra-processed (65·1 %) products more often than traditional supermarket chains (69·6 % and 56·6 %, respectively). CONCLUSIONS: The majority of promoted products via supermarket sales flyers do not contribute to a healthy diet. As promotions are an important determinant of food purchasing decisions, supermarkets do not support healthy choices. Future studies should identify barriers that withhold supermarket chains from promoting more healthy foods in supermarket sales flyers.

The Healthy Supermarket Coach: Effects of a Nutrition Peer-Education Intervention in Dutch Supermarkets Involving Adolescents With a Lower Education Level.

Supermarkets located near schools influence adolescents' food consumption. The aims of this study were (1) to measure dietary behaviors during school hours, (2) to investigate the effect of a nutrition peer-education intervention in supermarkets within walking distance to secondary schools on nutritional knowledge and attitudes toward healthy eating, and (3) to assess how the intervention was appraised by adolescents with a lower education level. The participants were adolescents aged 12 to 14 years from four secondary schools in Amsterdam, the Netherlands (n = 432). Cross-sectional analyses were performed to establish dietary behaviors (pretest). A quasi-experimental pre-post design with a comparison school was used (n = 3 intervention, n = 1 comparison). Intervention schools received the intervention in a supermarket near their school. The comparison school received no intervention. The appraisal of the intervention was assessed in the intervention schools (posttest). Most of the adolescents who purchased foods from retail food outlets near the school (71.1%) did so from supermarkets (88.6%). The nutritional knowledge scores (ß = 0.69, 95% CI [0.23, 1.15], p = .003) as well as the attitudes toward healthy eating (ß = 0.17, 95% CI [0.04, 0.29], p = .009) of adolescents from the intervention schools were statistically significantly higher after the intervention, relative to the comparison school. Nutrition peer education in supermarkets can improve nutritional knowledge and attitudes toward healthy eating among adolescents with a lower education. Future research on the short- and long-term effects of nutrition peer education on food purchases and dietary intake of adolescents is needed.

Can Healthy Checkout Counters Improve Food Purchases? Two Real-Life Experiments in Dutch Supermarkets.

Most snacks displayed at supermarket checkouts do not contribute to a healthy diet. We investigated the effects of introducing healthier snack alternatives at checkouts in supermarkets on purchasing behavior. In Study 1, we investigated the effect of completely substituting less healthy with healthier snacks (one supermarket). In Study 2, we investigated the effect of placing and discounting healthier snacks while the less healthy snacks remain in place (two supermarkets). In both studies, the number of purchased snacks (per 1000 customers) was used as the outcome variable. Results for Study 1 showed that the absolute number of purchased checkout snacks was 2.4 times lower (95% confidence interval (CI): 1.9-2.7) when healthier snacks instead of less healthy snacks were placed at the supermarket checkouts. Results for Study 2 showed that when additional healthier snacks were placed near the checkouts, the absolute number of healthier purchased snacks increased by a factor of 2.1 (95% CI: 1.3-3.3). When additional healthier snacks were placed near the checkouts and discounted, the absolute number of healthier purchased snacks increased by a factor of 2.7 (95% CI: 2.0-3.6), although this was not statistically significant higher than placement only (ratio: 1.1, 95% CI: 0.7-1.9). Purchases of less healthy snacks did not decline, and even slightly increased, during the intervention period (ratio: 1.3, 95% CI: 1.1-1.5). If supermarkets want to promote healthier snack purchases, additional healthier products can be positioned near the checkouts. However, this does not discourages the purchase of less healthy snacks. Therefore, to discourage unhealthy snack purchases at supermarket checkouts, a total substitution of less healthy snacks with healthier alternatives is most effective.

Can unhealthy food purchases at checkout counters be discouraged by introducing healthier snacks? A real-life experiment in supermarkets in deprived urban areas in the Netherlands.

BACKGROUND: The checkout area in supermarkets is an unavoidable point of purchase where impulsive food purchases are likely to be made. However, the product assortment at the checkout counters is predominantly unhealthy. The aim of this real life experiment was to investigate if unhealthy food purchases at checkout counters in supermarkets in deprived urban areas in the Netherlands can be discouraged by the introduction of the Healthy Checkout Counter (HCC). In addition, we examined customers' perceptions towards the HCC. METHODS: The HCC was an initiative of a leading supermarket chain in the Netherlands that consisted of displays with a selection of healthier snacks that were placed at the checkouts. We used a real life quasi-experimental design with 15 intervention and 9 control supermarkets. We also performed a cross-sectional customer evaluation in 3 intervention  supermarkets using oral surveys to investigate customers' perceptions towards the HCC (n=134). The purchases of unhealthy and healthier snacks at checkouts were measured with sales data. RESULTS: During the intervention period, customers purchased on average 1.7 (SD: 0.08) unhealthy snacks per 100 customers in the intervention supermarket and 1.4 (SD: 0.10) in the control supermarket. Linear regression analyses revealed no statistically significant difference in the change during the control and intervention period of sales of unhealthy snacks between the control and intervention supermarkets (B = - 0.008, 95% CI = - 0.15 to 0.14). The average number of healthier snacks purchased was 0.2 (SD: 0.3) items per 100 customers in the intervention supermarkets during the intervention period. Of the intervention customers, 41% noticed the HCC and 80% of them were satisfied or very satisfied with the intervention. CONCLUSIONS: This real life experiment in supermarkets showed that the placement of healthier snacks at checkouts did not lead to the substitution of unhealthy snack purchases with healthier alternatives. Although supermarket customers positively evaluated the HCC, future studies are needed to investigate other strategies to encourage healthier food purchases in supermarkets.

Social norm nudges in shopping trolleys to promote vegetable purchases: A quasi-experimental study in a supermarket in a deprived urban area in the Netherlands.

BACKGROUND: Supermarkets are a key point of purchase for groceries and can therefore have a considerable influence on eating behaviours. Evidence suggests that descriptive social norm nudges in shopping trolleys can be effective in stimulating vegetable purchases in supermarkets. OBJECTIVE: We investigated the effect of a combination of two nudging strategies in shopping trolleys - a social norm about vegetable purchases and a designated place to put vegetables - on the amount of vegetables purchased in a supermarket in a deprived urban area in the Netherlands. DESIGN: A quasi-experimental study was conducted with two conditions: 1) intervention days on which the shopping trolleys in the supermarket had a green nudge inlay indicating a place for vegetables and a social norm message and 2) control days on which the regular shopping trolleys (no inlay or social norm) were used in the supermarket. During both the intervention and control days, vegetable purchases were measured by means of the cash receipts collected from customers at the checkouts. In addition, individual and purchase characteristics were assessed by means of short surveys. RESULTS: In total, 244 customers participated in the study. Ordinal logistic regression analyses showed that customers on the intervention days (n = 123) were in a higher tertile for grams of vegetables purchased compared to the customers on the control days (OR: 1.66, 95% CI: 1.03-2.69, p = 0.03), especially those who bought groceries for less than three days (OR: 3.24, 95% CI: 1.43-7.35, p = 0.003). Sensitivity analyses also showed that intervention customers who noticed the green inlay were even more likely to purchase more vegetables (OR: 1.86, 95% CI: 1.06-3.25, p = 0.02). CONCLUSIONS: This quasi-experimental study showed that a nudge inlay in shopping trolleys communicating a social norm on vegetable purchases and indicating a distinct place to put vegetables in the trolley increased vegetable purchases among supermarket customers.

'Obesogenic' School Food Environments? An Urban Case Study in The Netherlands.

(1) Background: This study aimed to explore and define socio-economic (SES) differences in urban school food environments in The Netherlands. (2) Methods: Retail food outlets, ready-to-eat products, in-store food promotions and food advertisements in public space were determined within 400 m walking distance of all secondary schools in the 4th largest city of The Netherlands. Fisher's exact tests were conducted. (3) Results: In total, 115 retail outlets sold ready-to-eat food and drink products during school hours. Fast food outlets were more often in the vicinity of schools in lower SES (28.6%) than in higher SES areas (11.5%). In general, unhealthy options (e.g., fried snacks, sugar-sweetened beverages (SSB)) were more often for sale, in-store promoted or advertised in comparison with healthy options (e.g., fruit, vegetables, bottled water). Sport/energy drinks were more often for sale, and fried snacks/fries, hamburgers/kebab and SSB were more often promoted or advertised in lower SES areas than in higher SES-areas. (4) Conclusion: In general, unhealthy food options were more often presented than the healthy options, but only a few SES differences were observed. The results, however, imply that efforts in all school areas are needed to make the healthy option the default option during school time.

Menu-engineering in restaurants - adapting portion sizes on plates to enhance vegetable consumption: a real-life experiment.

BACKGROUND: The aim of this research was to investigate whether increased portion sizes of vegetables and decreased portion sizes of meat on main dishes increased the amount of vegetables consumed in a real-life restaurant setting without affecting customer satisfaction. The participants were unaware of the experiment. METHODS: A cross-over design was used in which three restaurants were randomly assigned to a sequence of an intervention and control condition. In the intervention period, the vegetable portion sizes on the plates of main dishes were doubled (150 g of vegetables instead of 75 g) and the portion sizes of meat on the plates were reduced by an average of 12.5%. In the control period, the portion sizes of the main dishes were maintained as usual. In total, 1006 observations and questionnaires were included. RESULTS: Vegetable consumption from plates was significantly higher during the intervention period (M = 115.5 g) than during the control period (M = 61.7 g). Similarly, total vegetable consumption (including side dishes) was significantly higher during the intervention period (M = 178.0 g) than during the control period (M = 137.0 g). Conversely, meat consumption was significantly lower during the intervention period (M = 183.1 g) than during the control period (M = 211.1 g). Satisfaction with the restaurant visit did not differ between the intervention period (M = 1.27) and control period (M = 1.35). Satisfaction with the main dish was significantly lower during the intervention period (M = 1.25) than during the control period (M = 1.38), although in both cases, the scores indicated that participants remained (very) satisfied with their main dish. CONCLUSIONS: This study showed that increasing vegetable portions in combination with decreasing meat portions (unknowingly to the consumer) increased the amount of vegetables consumed and decreased the amount of meat consumed. Furthermore, despite the changes in portion sizes, participants remained satisfied with their restaurant visit and main dish. The findings of this study suggest that modifying portion size in restaurants is an effective tool for stimulating vegetable consumption and consequently healthy and sustainable diets.