Effects of different discount levels on healthy products coupled with a healthy choice label, special offer label or both: results from a web-based supermarket experiment

Evaluating the relative impact of multiple healthy food choice interventions on choice process variables and choices

Fiscal tools-taxes and/or subsidies-are increasingly used to address diet-related health problems. However, some studies have found that these tools are markedly more effective if attention is drawn to the tax or subsidy, suggesting that the price change alone may go unnoticed in the complex food environments that consumers face. Interventions that prompt individuals to consider health during choice show promise for promoting healthy food choices in both simple laboratory settings and complex, real-world markets. In this pre-registered study, I examine the impact of dietary fiber health prompts and/or dietary fiber subsidies on the per-serving fiber content of foods chosen, the documented set of products considered, and (self-reported) nutrition information use by participants in an online supermarket setting. Participants were randomized to one of four conditions: 1) control, 2) subsidy, 3) fiber prompt, and 4) fiber prompt + subsidy. Results show that both the prompt and prompt + subsidy conditions significantly increase fiber content of foods chosen (with the latter having a larger effect). While all three interventions influence the probability of using nutrition information during food choice and affect the set of products that respondents consider relative to the control condition, the effects were larger for the prompt and prompt + subsidy conditions. A multiple mediation analysis illustrates that both direct and indirect (through the set of products considered and the use of fiber information during choice) pathways lead to the significant overall increase in fiber content of selected foods.

Effect of a relative pricing intervention and active merchandising on snack purchases: interrupted time series analysis of a hospital retailer-led strategy

BACKGROUND

Pricing policies have been shown to be an effective lever for promoting healthier dietary choices in consumer food environments. It is not yet well understood how pricing can be used to encourage healthier substitute purchases. The aim of the study was to assess the effect of a retailer-led relative pricing intervention on weekly purchases of targeted snack foods and beverages.

METHODS

This was an ecological analysis in a real-world large tertiary hospital consumer food environment setting in urban Canada, comprised of four retail outlets: two large cafeterias, one smaller cafeteria, and one grab-and-go café. An interrupted time series analysis was designed to evaluate the effect of Snacking Made Simple, a retailer-led relative pricing intervention applied to 10 popular snack foods and beverages (n = 87 weeks, 66 weeks baseline and 21 weeks intervention, April 2018 to December 2019), on weekly purchase differences between healthier and less healthy targeted items, adjusted for weekly sales volume. Five healthier items were price discounted, alongside a price increase for five less healthy items. The intervention was actively merchandised in keeping with behaviour change theory.

RESULTS

Weekly purchases of targeted snacks became healthier during the intervention period (β = 21.41, p = 0.0024). This followed a baseline period during which weekly purchases of less healthy targeted snacks had outpaced over time those of healthier targeted snacks (β = -11.02, p = 3.68E-14). We estimated that, all else being equal, a hypothetical 9.43 additional weeks of the intervention would be required to transition to net-healthier targeted snack purchases in this environment. The effects of the intervention varied by retail outlet, and the outcome appears driven by specific food items; further, examining merchandising implementation, we posited whether direct versus indirect substitution may have affected purchasing outcomes.

CONCLUSIONS

Relative pricing may be a promising way to incentivize healthier substitute purchasing in the consumer food environment. Added attention to merchandising strategy as well as value-add factors within food categories and their effects on price salience may be an important factor in effective intervention design.

The impact of the consumer and neighbourhood food environment on dietary intake and obesity-related outcomes: A systematic review of causal impact studies

BACKGROUND

The food environment has been found to impact population dietary behaviour. Our study aimed to systematically review the impact of different elements of the food environment on dietary intake and obesity.

METHODS

We searched MEDLINE, Embase, PsychInfo, EconLit databases to identify literature that assessed the relationship between the built food environments (intervention) and dietary intake and obesity (outcomes), published between database inception to March 26, 2020. All human studies were eligible except for those on clinical sub-groups. Only studies with causal inference methods were assessed. Studies focusing on the food environment inside homes, workplaces and schools were excluded. A risk of bias assessment was conducted using the CASP appraisal checklist. Findings were summarized using a narrative synthesis approach.

FINDINGS

58 papers were included, 55 of which were conducted in high-income countries. 70% of papers focused on the consumer food environments and found that in-kind/financial incentives, healthy food saliency, and health primes, but not calorie menu labelling significantly improved dietary quality of children and adults, while BMI results were null. 30% of the papers focused on the neighbourhood food environments and found that the number of and distance to unhealthy food outlets increased the likelihood of fast-food consumption and higher BMI for children of any SES; among adults only selected groups were impacted - females, black, and Hispanics living in low and medium density areas. The availability and distance to healthy food outlets significantly improved children's dietary intake and BMI but null results were found for adults.

INTERPRETATION

Evidence suggests certain elements of the consumer and neighbourhood food environments could improve populations dietary intake, while effect on BMI was observed among children and selected adult populations. Underprivileged groups are most likely to experience and impact on BMI. Future research should investigate whether findings translate in other countries.

Food promotions and the cost of a healthy diet

With approximately two in three UK adults overweight or obese, one in five living in poverty and our emergence from the Covid-19 pandemic with implications for employment and income status there is an urgent need to understand what it costs to eat healthily and the role that promotions can play in helping householders manage food budgets. The literature suggests that, in affluent countries, price promotions appear to increase consumer food purchases and are applied more frequently to less healthy products than their healthy counterparts. This review discusses the cost of a healthy diet, identifies the prevalence of promotions in both the supermarket setting generally and a typical shopping basket specifically, and discusses the barriers to affording a healthy diet. Given the current policy focus on the cost of living and population health emphasising the need for food shopping to represent health and value for money for better public health outcomes, this review contributes to the evidence base for retailers' and policymakers' consideration as policy solutions are sought to reduce population obesity levels, while ensuring the affordability and accessibility of nutritious food. It is important, given the shift in consumer purchasing behaviour to online shopping as a result of self-isolating or reticence to physically access stores in response to the Covid-19 pandemic, that retail food promotions are available irrespective of the chosen mode of shopping (in-store or online).

Helping parents provide vegetable snacks: Investigating price and taste as barriers

Snacks contribute nearly one-quarter of children's daily energy intake in the USA. Snack time therefore represents an opportunity for parents to provide foods with key nutrients. Instead, the most common snack foods are major contributors to children's consumption of added sugars and sodium. Parents face major barriers to providing healthier snacks, including perceptions of high cost and lack of child acceptance. We obtained both economic and qualitative data to inform and optimize interventions for parents to promote vegetable snacks for children. We conducted a survey with parents (n = 368) to estimate how much of a discount would influence vegetable snack purchases by estimating willingness-to-pay using the contingent valuation method, using baby-cut carrots as a sample product. We conducted three focus groups (n = 19) and 1 group interview (n = 2) with children to help understand how to increase the appeal of vegetable snacks. Most (70%) parents accepted the reference price for the vegetable snack. Among those who did not, contingent valuation analysis revealed that a mean discount of approximately 30% would shift consumers to purchasing the snack. Focus group results revealed that the appeal of vegetable snacks to children was influenced by how they were prepared and presented, and the child's familiarity with the vegetables and ability to choose among them. This study lays the groundwork for effective interventions to promote the provision of vegetable snacks by parents.

Demographic, Anthropometric and Food Behavior Data towards Healthy Eating in Romania

Background: Each country has specific social, cultural, and economic characteristics regarding the motivations for improving health. The aim of this study was to evaluate demographic characteristics, anthropometric data, and elements related to food behavior and health, as well as Romanians’ motivations towards healthy eating. Methods: This is a descriptive cross-sectional questionnaire based study enrolling 751 Romanian participants, which was carried out in in 2017–2018. Results: We obtained a positive correlation between age and Body Mass Index, and this was maintained also when we analyzed the two genders separately, being, however, even stronger for women. The number of hours/day spent watching TV or in front of the computer was positively correlated with both age and BMI. In general, with aging, there is an increasing concern regarding the practice of a healthy diet. The higher education level was significantly associated with healthier choices. Conclusions: The study of the three dietary dimensions, food properties, health attitudes, and dietary behavior, vis-à-vis various disorders revealed that the group most concerned of their diet was those who suffered from cardiovascular disorders.

Effect of front-of-package nutrition labeling on food purchases: a systematic review

OBJECTIVES

This study systematically reviewed evidence from interventions on the effect of front-of-package (FOP) nutrition labeling on food purchases.

STUDY DESIGN

The study design used in this study is a systematic review.

METHODS

Keyword search was performed in PubMed, Web of Science, Scopus, and Cochrane Library.

RESULTS

Fifteen studies (10 randomized controlled trials, four pre-post studies, and one case-control study) met the eligibility criteria and were included in the review. Five studies were conducted in a controlled setting through the establishment of an online virtual supermarket or physical laboratory food store solely for the intervention. In contrast, the remaining ten studies were conducted in a naturalistic setting where people commonly purchase foods (e.g., supermarket, grocery store, school/hospital cafeteria, or vending machine). FOP labels assessed included traffic lights, health star rating, daily intake guides, health warnings, and high sugar symbol labels. Compared with the control, FOP labels were effective for helping participants make healthier food purchase decisions in five of the 12 studies that assessed traffic lights labels, in one of the two studies that assessed health warning labels, and in one study that assessed high sugar symbol labels. Three assessed health star ratings and one assessed daily intake guide labels, but none revealed an effect on food purchases compared with the control.

CONCLUSIONS

Findings on the effectiveness of FOP nutrition labels in 'nudging' consumers toward healthier food purchases remain mixed and inconclusive. Future studies should examine other types of FOP labels beside the traffic lights labels and explore the different effects by consumer affordability, population subgroup, and shopping environment.

What Makes a Front-of-Pack Nutritional Labelling System Effective: The Impact of Key Design Components on Food Purchases

The relative impacts on food purchases of many alternative front-of-pack nutritional labelling systems were tested, with various methods—from opinion pool to nationwide experiments. Clearly, some systems induce better purchasing responses, having better nutritional impacts on food baskets. Nonetheless, we still ignore what the ingredients of an efficient label are. Here, we propose guidance for label designers. To do so, we first propose a typology that breaks down established labelling systems into four elementary components: Directiveness, Scope and Gradation, Set of Reference and Sign. On this basis, we then build seven alternative generic labelling systems that we test in a framed-field experiment enabling us to measure the effect of each component on food purchases in isolation. Our results show that an effective front-of-pack labelling system should be Food-Directive (instead of Diet-Directive) and be displayed on both healthy and unhealthy food. The reference set, which is across categories or within categories, produces the same average nutrition score but generates contrasting behavioural responses.

Compared to other front-of-pack nutrition labels, the Nutri-Score emerged as the most efficient to inform Swiss consumers on the nutritional quality of food products

Background

Switzerland, like other high-income countries, is facing a major public health challenge with the increasing burden of non-communicable diseases. Discussions are currently on-going in Switzerland regarding the implementation of a Front-of-Pack nutrition label (FoPL) as a public health measure to guide consumers towards healthier food choices, and the Nutri-Score represents an alternative supported by multiple actors. To date, no studies have investigated the performance of the Nutri-Score among Swiss consumers. This study aimed to compare the response of Swiss consumers to five FoPLs (Health Star Rating system, Multiple Traffic Lights, Nutri-Score, Reference Intakes and Warning symbol) in terms of perception and understanding of these labels and effects on food choices.

Methods

In 2019, 1,088 Swiss consumers were recruited and asked to select one product from among a set of three foods with different nutritional profiles and then classify the products within the sets according to their nutritional quality. Tasks were performed in situations without a label and then with one of the five FoPLs–depending on the group in which they were randomized–on the pack. Finally, participants were questioned on their perceptions regarding the label to which they were exposed.

Results

All FoPLs were favorably perceived, with marginal differences between FoPLs. The Nutri-Score demonstrated the highest percentage of improvement in food choices and the highest overall performance in helping consumers rank the products according to their nutritional quality.

Conclusion

Overall, the Nutri-Score was the most efficient FoPL in informing Swiss consumers of the nutritional quality of food products, and as such could be a useful tool to improve food choices and reduce the burden of chronic diseases in Switzerland.

Consumer beliefs about healthy foods and diets

Background

The U.S. Food and Drug Administration has begun a public process to redefine how companies are allowed to use the term “healthy” on food packages. Although the definition is formulated based on the latest consensus in nutrition and epidemiological research, it is also important to understand how consumers define and understand the term if it is to be behaviorally relevant. This research is an exploratory study designed to provide a descriptive account of consumers’ perceptions of and beliefs about the meaning of “healthy” food.

Methods

A nationwide U.S. sample of 1,290 food consumers was surveyed in December 2018. Respondents answered 15 questions designed to gauge perceptions of healthy food and to elicit preference for policies surrounding healthy food definitions. Responses are weighted to demographically match the population. Categorical variables have a sampling error of ±2.7%. Exploratory factor analysis is used to determine latent dimensions of health perceptions related to food type.

Results

Consumers were about evenly split on whether a food can be deemed healthy based solely on the foods’ nutritional content (52.1% believing as such) or whether there were other factors that affect whether a food is healthy (47.9% believing as such). Consumers were also about evenly split on whether an individual food can be considered healthy (believed by 47.9%) or whether this healthiness is instead a characteristic of one’s overall diet (believed by 52.1%). Ratings of individual food products revealed that “healthy” perceptions are comprised of at least three underlying latent dimensions related to animal origin, preservation, and freshness/processing. Focusing on individual macronutrients, perceived healthiness was generally decreasing in a food’s fat, sodium, and carbohydrate content and increasing in protein content. About 40% of consumers thought a healthy label implied they should increase consumption of the type of food bearing the label and about 15% thought the label meant they could eat all they wanted.

Conclusions

Results suggest consumer’s perceptions of “healthy,” which is primarily based on fat content, partially aligns with the FDA definition but also suggest consumers perceive the word as a broader and more nuanced concept that defies easy, uniform definition. Results highlight areas where nutrition education may be needed and suggest disclosures may need to accompany health claims so that consumers know what, precisely, is being communicated.

Consumers' Responses to Front-of-Pack Nutrition Labelling: Results from a Sample from The Netherlands

Front-of-pack labels (FoPLs) are efficient tools for helping consumers identify healthier food products. Although discussions on nutritional labelling are currently ongoing in Europe, few studies have compared the effectiveness of FoPLs in European countries, including the Netherlands. This study aimed to compare five FoPLs among Dutch participants (the Health Star Rating (HSR) system, Multiple Traffic Lights (MTL), Nutri-Score, Reference Intakes (RIs), and Warning symbols) in terms of perception and understanding of the labels and food choices. In 2019, 1032 Dutch consumers were recruited and asked to select one product from among a set of three foods with different nutritional profiles, and then rank the products within the sets according to their nutritional quality. These tasks were performed with no label and then with one of the five FoPLs on the package, depending on the randomization arm. Finally, participants were questioned on their perceptions regarding the label to which they were exposed. Regarding perceptions, all FoPLs were favorably perceived but with only marginal differences between FoPLs. While no significant difference across labels was observed for food choices, the Nutri-Score demonstrated the highest overall performance in helping consumers rank the products according to their nutritional quality.

The Effect of Randomly Providing Nutri-Score Information on Actual Purchases in Colombia

Recently, front-of-package (FOP) food labeling systems have captured the attention of researchers and policy makers. Several Latin American governments are currently considering employing different FOP labeling systems. However, there is much need for more research-based evidence in these countries. In this paper, we study whether food-purchasing decisions and the nutritional qualities of those purchases are influenced by randomly informing some customers and not others about an FOP label known as Nutri-Score. We also separate the information effect from the effect of being aware of the system. We combined a randomized field intervention in a university cafeteria in Bogotá, Colombia with data from an after-purchase survey and receipts. We found that randomly providing information on Nutri-Score increased total expenditure by $0.18. Additional spending on healthier items was 21% or $0.26 higher, with no change for less healthy items. Expenditure estimates were higher among customers who were aware of the system’s existence. Customers in the study were also 10% more likely to buy a healthier item than control customers were, and the concentration of protein in their purchases was greater. Information on the Nutri-Score system increased the store’s sales. This potential financial incentive may facilitate the implementation of Nutri-Score.

Food healthiness versus tastiness: Contrasting their impact on more and less successful healthy shoppers within a virtual food shopping task

A virtual shopping task was employed to illuminate why women who intend to shop healthily are differentially successful in doing so. Female undergraduates (N = 68) performed a modified approach and avoidance task that employed food items differing in healthiness and tastiness, and yielded relative speed to select and reject food items in a stylised supermarket. Participants categorised a food item either in terms of healthiness or tastiness, then pulled (selected) or pushed (rejected) the item using a joystick. Participants showed faster selection of tasty food after categorisation in terms of tastiness, irrespective of the food's healthiness. However, after categorisation in terms of healthiness, only more successful healthy food shoppers showed faster selection of healthy items regardless of tastiness. Less successful healthy food shoppers showed this effect only for tasty food, and displayed faster rejection of food items not considered tasty, regardless of their assessed healthiness. Thus, when participants who reported the greatest gap between their shopping intention and shopping behaviour were judging the healthiness of food items, their speed to select and reject items continued to be influenced by tastiness. This suggests that reducing incidental processing of food tastiness may reduce the intention-behaviour gap in healthy food shopping.

Grocery store interventions to change food purchasing behaviors: a systematic review of randomized controlled trials

Background

Diet is an important determinant of health, and food purchasing is a key antecedent to consumption.

Objective

We set out to evaluate the effectiveness of grocery store interventions to change food purchasing, and to examine whether effectiveness varied based on intervention components, setting, or socioeconomic status.

Design

We conducted a systematic review of randomized controlled trials (search performed June 2017). Studies must have: aimed to change food purchasing; been implemented in grocery stores (real or simulated); reported purchasing; and had a minimal control or compared interventions fulfilling our criteria. Searching, screening, bias assessment, and data extraction followed Cochrane methods. We grouped studies by intervention type (economic, environmental, swaps, and/or education), synthesized results narratively, and conducted an exploratory qualitative comparative analysis.

Results

We included 35 studies representing 89 interventions, >20,000 participants, and >800 stores. Risk of bias was mixed. Economic interventions showed the most promise, with 8 of the 9 studies in real stores and all 6 in simulated environments detecting an effect on purchasing. Swap interventions appeared promising in the 2 studies based in real stores. Store environment interventions showed mixed effects. Education-only interventions appeared effective in simulated environments but not in real stores. Available data suggested that effects of economic interventions did not differ by socioeconomic status, whereas for other interventions impact was variable. In our qualitative comparative analysis, economic interventions (regardless of setting) and environmental and swap interventions in real stores were associated with statistically significant changes in purchasing in the desired direction for ≥1 of the foods targeted by the intervention, whereas education-only interventions in real stores were not.

Conclusions

Findings suggest that interventions implemented in grocery stores-particularly ones that manipulate price, suggest swaps, and perhaps manipulate item availability-have an impact on purchasing and could play a role in public health strategies to improve health. Review protocol registered at https://www.crd.york.ac.uk/PROSPERO/ as CRD42017068809.

Using a UK Virtual Supermarket to Examine Purchasing Behavior Across Different Income Groups in the United Kingdom: Development and Feasibility Study

BACKGROUND

The majority of food in the United Kingdom is purchased in supermarkets, and therefore, supermarket interventions provide an opportunity to improve diets. Randomized controlled trials are costly, time-consuming, and difficult to conduct in real stores. Alternative approaches of assessing the impact of supermarket interventions on food purchases are needed, especially with respect to assessing differential impacts on population subgroups.

OBJECTIVE

The aim of this study was to assess the feasibility of using the United Kingdom Virtual Supermarket (UKVS), a three-dimensional (3D) computer simulation of a supermarket, to measure food purchasing behavior across income groups.

METHODS

Participants (primary household shoppers in the United Kingdom with computer access) were asked to conduct two shopping tasks using the UKVS and complete questionnaires on demographics, food purchasing habits, and feedback on the UKVS software. Data on recruitment method and rate, completion of study procedure, purchases, and feedback on usability were collected to inform future trial protocols.

RESULTS

A total of 98 participants were recruited, and 46 (47%) fully completed the study procedure. Low-income participants were less likely to complete the study (P=.02). Most participants found the UKVS easy to use (38/46, 83%) and reported that UKVS purchases resembled their usual purchases (41/46, 89%).

CONCLUSIONS

The UKVS is likely to be a useful tool to examine the effects of nutrition interventions using randomized controlled designs. Feedback was positive from participants who completed the study and did not differ by income group. However, retention was low and needs to be addressed in future studies. This study provides purchasing data to establish sample size requirements for full trials using the UKVS.

Effectiveness of Pricing Strategies on French Fries and Fruit Purchases among University Students: Results from an On-Campus Restaurant Experiment

Objectives

This study examined the effect of a 10 and 20% meal price increase when choosing French fries and a 10 and 20% meal price reduction when choosing fruit for dessert on university students’ purchasing behaviour in an on-campus restaurant. The moderating effect of gender was also investigated. Secondly, this study aimed at gaining further insight into reasons why these price manipulations did or did not change students’ purchasing behaviour.

Materials and Methods

This two-phased mixed-methods study was conducted in a Belgian on-campus university restaurant with approximately 1200 to 1300 student visitors per day. In a first phase (French fries experiment), data were collected during a control week (no price manipulation) and two separate intervention weeks (10 and 20% meal price increase when students chose French fries). In a second phase (fruit experiment), following the same protocol but carried out a few weeks later, meal prices were reduced by 10 and 20% when students chose fruit for dessert. French fries and fruit sale counts relative to the total number of items sold were used as outcome measure. Short interviews were conducted in convenient subsamples of student customers to assess influences on food choice.

Key findings

Increasing the meal price by 10 and 20% when choosing French fries was associated with respective 10.9 and 21.8% absolute reductions in French fries purchases, while reducing the meal price by 10 and 20% when choosing fruit for dessert was associated with absolute increases in fruit purchases of respectively 25.1 and 42.4% (all p<0.001). No moderating effect of gender was detected. Besides price, food/taste preference, eating habits, health, availability and accessibility, and body satisfaction influenced students’ food choices, with taste being the most frequently mentioned factor.

Significance

Pricing may be a promising strategy to improve university students’ eating behaviour. The likelihood of intervention success may increase when combining pricing strategies with offering healthy, tasty and meal matching starchy alternatives to French fries and offering a variety of fresh and appealing fruits.

Preferred Healthy Food Nudges, Food Store Environments, and Customer Dietary Practices in 2 Low-Income Southern Communities

OBJECTIVE

To examine how food store environments can promote healthful eating, including (1) preferences for a variety of behavioral economics strategies to promote healthful food purchases, and (2) the cross-sectional association between the primary food store where participants reported shopping, dietary behaviors, and body mass index.

METHODS

Intercept survey participants (n = 342) from 2 midsized eastern North Carolina communities completed questionnaires regarding preferred behavioral economics strategies, the primary food store at which they shopped, and consumption of fruits, vegetables, and sugary beverages.

RESULTS

Frequently selected behavioral economic strategies included: (1) a token and reward system for fruit and vegetable purchases; and (2) price discounts on healthful foods and beverages. There was a significant association between the primary food store and consumption of fruits and vegetables (P = .005) and sugary beverages (P = .02).

CONCLUSIONS AND IMPLICATIONS

Future studies should examine associations between elements of the in-store food environment, purchases, and consumption.

Impact of the front-of-pack 5-colour nutrition label (5-CNL) on the nutritional quality of purchases: an experimental study

Background

Front-of-pack (FOP) nutrition labelling has received growing attention from public health authorities, as a tool to promote healthier diets in the population. Recently, the French Health law introduced the principle of implementing a FOP nutrition labelling system. A scientific proposal has put forward the 5-Colour Nutrition Label (5-CNL), a five-category colour-coded summary system supported by research suggesting that it is well perceived and understood in the population. Our objective was to investigate the impact of the 5-CNL on the nutritional quality of purchases in experimental supermarkets.

Methods

Participants (n = 901) were recruited using quota sampling between September and December 2015 and evenly distributed in three experimental conditions: 1) control situation; 2) Application of the 5-CNL on all food products in three specific sections: breakfast cereals, sweet biscuits and appetizers; 3) introduction of the 5-CNL accompanied by consumer information on use and understanding of the label. Main outcome was the nutritional quality of the shopping cart in the three sections combined, measured using the United Kingdom Food Standards Agency nutrient profiling system (FSA score).

Results

Significantly higher mean nutritional quality of the purchased items per section were observed for the sweet biscuits category in the intervention combining the label + communication (overall FSA score 21.01 vs. 20.23, P = 0.02). No significant effects were observed for the general mean over the three sections combined or other food categories. The results observed on purchase may be related to the high level of recall, self-reported and objective understanding of the label that were observed in the intervention groups as they are pre-requisites for use of a label in purchasing situations.

Conclusion

These results suggest that the 5-CNL FOP nutrition label may have a limited impact on purchases, leading to healthier food choices in some food categories such as sweet biscuits.

Trial registration

The trial was registered on Clinicaltrials.gov under the number NCT02546505.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-016-0416-4) contains supplementary material, which is available to authorized users.

Socioeconomic predictors of dietary patterns among Guatemalan adults

OBJECTIVES

We aimed to assess the associations of socioeconomic factors with dietary patterns in a Guatemalan population.

METHODS

Cross-sectional data of 1076 participants (42 % men, mean age 32.6 ± 4.2 years) collected between 2002 and 2004 in four rural villages in Guatemala. Dietary patterns were derived using principal component analysis. Chi-square and Poisson regression models were used to assess associations between socioeconomic factors and dietary patterns.

RESULTS

Three dietary patterns were identified: "Western" (high in processed foods), "traditional" (high in traditional foods) and "coffee and sugar", explaining 11, 7 and 6 % of the variance, respectively. Annual expenditures were associated with a higher adherence to the "Western" pattern: prevalence ratios [(PR) (95 % confidence interval)] 1.92 (1.17-3.15) for the highest vs. lowest expenditure group in men and 8.99 (3.57-22.64) in women. A borderline significant (p = 0.06) negative association was found between the "traditional" pattern and higher household expenditures [0.71 (0.49-1.02) in men] and with schooling [0.23 (0.05-1.02)] in women (p = 0.05).

CONCLUSIONS

Dietary patterns in Guatemala are predicted by socioeconomic factors. In particular, high annual expenditures are associated with a more westernized, less traditional diet.

CVD Prevention Through Policy: a Review of Mass Media, Food/Menu Labeling, Taxation/Subsidies, Built Environment, School Procurement, Worksite Wellness, and Marketing Standards to Improve Diet

Poor diet is the leading cause of cardiovascular disease in the USA and globally. Evidence-based policies are crucial to improve diet and population health. We reviewed the effectiveness for a range of policy levers to alter diet and diet-related risk factors. We identified evidence to support benefits of focused mass media campaigns (especially for fruits, vegetables, salt), food pricing strategies (both subsidies and taxation, with stronger effects at lower income levels), school procurement policies (for increasing healthful or reducing unhealthful choices), and worksite wellness programs (especially when comprehensive and multicomponent). Evidence was inconclusive for food and menu labeling (for consumer or industry behavior) and changes in local built environment (e.g., availability or accessibility of supermarkets, fast food outlets). We found little empiric evidence evaluating marketing restrictions, although broad principles and large resources spent on marketing suggest utility. Widespread implementation and evaluation of evidence-based policy strategies, with further research on other strategies with mixed/limited evidence, are essential “population medicine” to reduce health and economic burdens and inequities of diet-related illness worldwide.

Impact of Different Front-of-Pack Nutrition Labels on Consumer Purchasing Intentions: A Randomized Controlled Trial

INTRODUCTION

Despite growing evidence supporting the utility of front-of-pack nutrition labels in enabling consumer evaluation of food product healthiness, research on food choices is scarce. This study aims at comparing the impact of front-of-pack nutrition labels on consumers' purchasing intentions.

DESIGN

Five-arm, open-label RCT.

SETTING/PARTICIPANTS

The study setting was a virtual web-based supermarket, with participants from the French NutriNet-Santé study. The eligibility requirement was grocery shopping involvement.

INTERVENTION

The intervention was to simulate one shopping situation with front-of-pack nutrition labels affixed on food products (December 2014 to March 2015). Participants were randomly assigned to one of five exposure conditions using a central computer system: Guideline Daily Amounts, Multiple Traffic Lights, Five-Color Nutrition Label, Green Tick, or control (no front-of-pack exposure). Given the nature of the intervention, masking of participants was not performed.

MAIN OUTCOME MEASURES

The primary outcome was the overall nutritional quality of the contents of the shopping cart, estimated using the United Kingdom Food Standards Agency nutrient profiling system. Secondary outcomes included energy and nutrient content of the shopping cart. Impact of the front-of-pack labels was also evaluated across sociodemographic subgroups based on age, educational level, income, and nutrition knowledge.

RESULTS

A total of 11,981 participants were included in the analyses (April 2015). The Five-Color Nutrition Label significantly led to the highest overall nutritional quality of the shopping cart, as reflected by lower Food Standards Agency scores (M=8.72; SD=2.75), followed by Multiple Traffic Lights (M=8.97; SD=2.68) and Green Tick (M=8.99; SD=2.71), compared with the control (M=9.34; SD=2.57) (p<0.0001). The Five-Color Nutrition Label was the only front-of-pack format that led to a lower content in lipids, saturated fatty acids, and sodium of the shopping cart (all p<0.05). The impact of the different front-of-pack labels was similar across sociodemographic subgroups.

CONCLUSIONS

The Five-Color Nutrition Label based on a color-coded and graded scale indicating overall nutritional quality is effective in promoting overall healthier food choices in all population subgroups.

TRIAL REGISTRATION

This study is registered at www.clinicaltrials.gov NCT02385838.

Offering within-category food swaps to reduce energy density of food purchases: a study using an experimental online supermarket

Background

Swaps are often used to encourage healthier food choices, but there is little evidence of their effectiveness. The current study assessed the impact of offering swaps on groceries purchased within a bespoke online supermarket; specifically the objective was to measure the impact on energy density (ED) of food purchases following the offer of lower ED alternatives (a) at point of selection or at checkout, and (b) with or without explicit consent to receive swap prompts.

Method

Participants were asked to complete a 12-item shopping task within an online shopping platform, developed for studying food purchasing. 1610 adults were randomly assigned to a no swap control condition or to one of four interventions: consented swaps at selection; consented swaps at checkout; imposed swaps at selection; or imposed swaps at checkout. Each swap presented two lower ED options from the same category as the participant’s chosen food. Swap acceptance rate and purchased food ED were the primary outcomes.

Results

Of the mean 12.36 (SD 1.26) foods purchased, intervention participants were offered a mean of 4.1 (SD 1.68) swaps, with the potential to reduce the ED of purchased food (effect (95 % CI): −83 kJ/100 g (−110 – -56), p = <0.0001). A median of one swap (IQR 0 to 2) was accepted, not significantly reducing the purchased food ED (effect (95 % CI): −24 kJ/100 g (4 – -52), p = 0.094). More swaps were accepted when offered at selection than at checkout (OR (95 % CI) = 1.224 (1.11 – 1.35), p < 0.0001), but no differences were seen with consent. Purchased food ED was unaffected by point of swap or consent, but reduced with number of swaps accepted (effect per swap (95 % CI) = −24 kJ/100 g (−35 – -14), p < 0.0001).

Conclusion

Within category swaps did not reduce the ED of food purchases reflecting the observation that the use of swaps within an on-line shopping platform offered small potential gains in ED and a minority was accepted.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-015-0241-1) contains supplementary material, which is available to authorized users.

Testing for baseline differences in randomized controlled trials: an unhealthy research behavior that is hard to eradicate

Background

According to the CONSORT statement, significance testing of baseline differences in randomized controlled trials should not be performed. In fact, this practice has been discouraged by numerous authors throughout the last forty years. During that time span, reporting of baseline differences has substantially decreased in the leading general medical journals. Our own experience in the field of nutrition behavior research however, is that co-authors, reviewers and even editors are still very persistent in their demand for these tests. The aim of this paper is therefore to negate this demand by providing clear evidence as to why testing for baseline differences between intervention groups statistically is superfluous and why such results should not be published.

Discussion

Testing for baseline differences is often propagated because of the belief that it shows whether randomization was successful and it identifies real or important differences between treatment arms that should be accounted for in the statistical analyses. Especially the latter argument is flawed, because it ignores the fact that the prognostic strength of a variable is also important when the interest is in adjustment for confounding. In addition, including prognostic variables as covariates can increase the precision of the effect estimate. This means that choosing covariates based on significance tests for baseline differences might lead to omissions of important covariates and, less importantly, to inclusion of irrelevant covariates in the analysis. We used data from four supermarket trials on the effects of pricing strategies on fruit and vegetables purchases, to show that results from fully adjusted analyses sometimes do appreciably differ from results from analyses adjusted for significant baseline differences only. We propose to adjust for known or anticipated important prognostic variables. These could or should be pre-specified in trial protocols. Subsequently, authors should report results from the fully adjusted as well as crude analyses, especially for dichotomous and time to event data.

Summary

Based on our arguments, which were illustrated by our findings, we propose that journals in and outside the field of nutrition behavior actively adopt the CONSORT 2010 statement on this topic by not publishing significance tests for baseline differences anymore.

Food prices and food shopping decisions of black women

Identifying food pricing strategies to encourage purchases of lower-calorie food products may be particularly important for black Americans. Black children and adults have higher than average obesity prevalence and disproportionate exposure to food marketing environments in which high calorie foods are readily available and heavily promoted. The main objective of this study was to characterize effects of price on food purchases of black female household shoppers in conjunction with other key decision attributes (calorie content/healthfulness, package size, and convenience). Factorial discrete choice experiments were conducted with 65 low- and middle-/higher-income black women. The within-subject study design assessed responses to hypothetical scenarios for purchasing frozen vegetables, bread, chips, soda, fruit drinks, chicken, and cheese. Linear models were used to estimate the effects of price, calorie level (or healthfulness for bread), package size, and convenience on the propensity to purchase items. Moderating effects of demographic and personal characteristics were assessed. Compared with a price that was 35% lower, the regular price was associated with a lesser propensity to purchase foods in all categories (β = -0.33 to -0.82 points on a 1 to 5 scale). Other attributes, primarily calorie content/healthfulness, were more influential than price for four of seven foods. The moderating variable most often associated with propensity to pay the regular versus lower price was the reported use of nutrition labels. Price reductions alone may increase purchases of certain lower-calorie or more healthful foods by black female shoppers. In other cases, effects may depend on combining price changes with nutrition education or improvements in other valued attributes.