Front-of-pack food labels (FOPLs) are designed to provide clear, accessible nutritional information to help consumers make informed choices. In an online experiment conducted with a large, representative British sample, researchers investigated whether FOPLs enhance the ability to evaluate the healthiness of food and drink items. The primary goal was to compare participants’ ability to rank products by healthiness across different FOPL formats and a no-label control group.
The study recruited adults (aged 18+) from the NatCen panel and randomly assigned them to one of five groups: Multiple Traffic Light (MTL), Nutri-Score (N-S), Warning Label (WL), Positive Choice tick (PC), or a no-label control. Participants were stratified by year of panel recruitment, sex, age, region, and household income.
Packaging images were created for six product types (pizza, drinks, cakes, crisps, yoghurts, and breakfast cereals), each with three variations differing in healthiness. Participants were asked to rank these images by healthiness in a baseline session (without FOPLs) and a follow-up session where FOPLs were applied according to their assigned group. The main outcome measured was the accuracy of ranking all products correctly (versus any incorrect rankings).
In 2020, data from 4,504 participants were analysed. Results showed that the probability of correctly ranking products at follow-up and improving from baseline was significantly higher for the N-S, MTL, and WL groups compared to the control. For the PC group, significant improvements were observed for only some products. Nutri-Score (N-S) had the largest positive impact, followed by the Multiple Traffic Light (MTL) system.
The analyses accounted for variables such as ethnicity, education, household composition, food shopping responsibility, and prior use of FOPLs. Exploratory findings indicated that participants with higher education levels were more likely to rank products accurately.
All FOPLs tested improved participants’ ability to accurately rank food and drink items by healthiness. The Nutri-Score showed the most substantial effects, followed by the Multiple Traffic Light system, demonstrating their potential value in guiding healthier consumer choices.
Obesity
Obesity continues to increase in many regions, and in young people, making it a key concern of policy makers. Front of pack labels (FOPLs) are simplified representations of the detailed nutrient declarations found on the back of food packaging and are one of the recommended policy actions for improving diet and addressing obesity [2,3]. FOPLs aim to provide clearly visible and easy to use information, but they vary greatly in the type of information presented (numbers, percentages, text), design (colour, shape), creation (industry or Government), and implementation (mandatory or voluntary). They can be interpretive (providing information about how healthy a food is) or non-interpretive (where there is no judgement, such as reference intakes, RI). There are numerous examples of interpretive labels, including nutrient specific interpretive; summary indicators; nutrient-specific warnings; and endorsement logos.
FOPLs are proposed to improve dietary quality through two main pathways: improving consumer understanding (reliant on consumer engagement) and driving product reformulation. Grunert and Wills present a theoretical framework describing factors involved in people’s responses to FOPLs, and propose that to be effective. A label must be seen, understood and liked by the consumer. They also identify modifying factors that affect label effectiveness, including nutrition knowledge, interest in nutrition, demographics, and label format. Research shows that consumer acceptability of FOPLs is high and that FOPLs are more likely to be used and easier to understand than nutrition information on the back of pack.
The influence of FOPLs on understanding is central to their effects and recent studies have examined this using ability to rank foods in order of “healthiness” as a marker of knowledge and understanding. An online experimental study in 12 countries tested the ability of participants to rank product healthiness, when randomised to one of five FOPL conditions. All FOPLs improved the ability of participants to correctly rank products, with the largest improvements seen for N-S, followed by the MTL, HSR, WL, and RI labels.
UK Standing on its Own
An extension of this study with an additional six countries showed consistent results. An online experimental study in Canada tested the ability of participants to rank food product healthiness, comparing MTL, HSR, WL and a no FOPL control. All labels improved the ability of participants to identify and rank unhealthy products, with the HSR and MTL groups performing the best.
Consumer engagement is essential for FOPLs to have an impact and research indicates that engagement is influenced by comprehension (nutritional knowledge) and motivation (such as interest in healthy eating), further highlighting the importance of understanding. There is also evidence that socio-demographic (e.g., socio-economic status, age, sex, ethnicity) and contextual factors (e.g., food packaging, size, and other information included on the front of pack) impact engagement.
In 2014, the WHO recommended “interactive and consumer-friendly” FOPLs as a policy priority in the European Union (EU). A 2019 analysis of global FOPL regulation identified 32 governments endorsing FOPLs, 10 of which are mandatory. The UK endorsed the MTL for voluntary use in 2013. Countries in the EU are constrained from implementing mandatory labels.
Now that the UK has left the EU, the UK Government has committed to review FOPLs to ensure that the country’s labelling scheme remains based on the latest evidence and to look at how MTL is implemented in the UK. Although evidence to date consistently supports FOPLs as a tool to improve consumers’ ability to identify healthier foods and encourage healthier food purchasing, research in representative UK samples has been limited. This research sought to inform policy making around future FOPL options in the UK. The main outcomes were the percentage of correct rankings (FOPLs vs. no label control), and the change in correct ranking from baseline to follow-up for food products individually and food products combined. Given the evidence supporting N-S, a secondary objective was to compare the effectiveness of N-S to the currently used MTL label at enabling an accurate product ranking.
Results
In this randomised controlled experiment, we found that, compared to a no FOPL control, all FOPLs significantly improved the ability of participants to correctly rank food and drink products according to healthiness. This was a consistent finding across all products and our three main outcomes, but the magnitude of the effects differed greatly between FOPL groups. The largest effects were seen for N-S, then MTL, WL and lastly, PC. The global food score analysis indicated that N-S led to improved rankings in an average of two product categories, compared to less than two categories for MTL (1.7) and WL (1.4). We also found that there was limited learning between baseline and follow-up ranking in the control group, indicating that the experiment worked, the findings are reliable, and the observed effects were solely due to the inclusion of the FOPL.
These findings are consistent with previous studies, where N-S has out-performed other FOPLs, but literature is limited as the N-S is relatively new. Results were similar in a Canadian study that included the HSR label (N-S and HSR are both summary indicator labels), suggesting that overall, these labels are more effective than the MTL label. However, the differences between MTL and either N-S or HSR were greater than the current study. As evidenced in these studies and the current study, FOPLs consistently improve the ability to rank products .
All of the FOPLs in our study were interpretive, in that they provide consumers with some judgement of the healthiness of the food. These labels typically perform better than non-interpretive labels and those that are simple and use aids (such as colour) have been found to be the easiest and most likely to be used. The use of colour could have contributed to the larger effects seen for N-S and MTL compared with WL and PC. N-S is a summary indicator label, which provides an overall nutritional assessment, whereas MTL provides nutrient-specific assessments, but no overall judgement. Others have found that interpretive labels providing an overall summary of healthiness are more helpful for consumers than those not providing a summary, but can lead to health halo effects.
The difference that we found between N-S and MTL appeared to be smaller than in other studies. This could be explained by participants being more familiar with the MTL, since the MTL has been in use in the UK since 2013 and understanding and knowledge have been shown to improve with familiarity with the label. This could also impact on subjective understanding directly (whether consumers think they have “understood” the information from the label) and through subconscious perception (exposure to familiar concepts leads to subconscious activation). Such factors could also have contributed to the larger effects seen for the MTL label than the WL and PC labels. Concerns over the accuracy of FOPL have been found to have a negative impact on use, and this could have reduced effects for less well-known labels such as N-S, WL, and PC. Overall, 75% of participants recalled seeing the FOPL that they were randomised to, N-S had the highest recall and PC the lowest; this is significant, as the perception of labels is a key factor in engagement, as highlighted in the Grunert and Wills conceptual framework. PC was least effective across the three outcomes; this is unsurprising, since endorsement labels are binary so provide limited information and two of the products did not qualify for any PC. Participants in MTL group scored highest for reporting “having enough information to rank”, despite N-S group generally performing better. This finding highlights the difference between objective understanding (outcomes of the ranking task) and subjective understanding (perceiving that they understood), where N-S resulted in highest objective but not highest subjective understanding.
Differences between product categories showed that yoghurt and breakfast cereal categories had the greatest improvements in correct ranking from baseline to follow-up, compared to the other foods. This shows that Front of Pack Food Labels‘ effectiveness might differ depending on product type and context or motivation for buying, such as hedonic pleasure. Both of these products may also be perceived as “healthy” products and often feature health claims (e.g., “light”, “low-fat”). Health claims (which were not included in the mock images) can bias opinions of food, which FOPLs have shown potential in reducing. These factors may explain the difference in responses and highlight the potential effectiveness of mandatory labels in these seemingly confusing products.
FOPLs’ effects were independent of SES, ethnicity, age, sex, household composition, food shopping responsibility, and current FOPL use. There was, however, a tendency for participants with higher education to be able to rank products with greater accuracy than those with less education. N-S seemed to show the smallest difference between groups with higher and lower education levels compared to other FOPL groups (especially marked for pizza, drinks, cake, and crisps, less so for yoghurts and breakfast cereals). In contrast to previous reports, the results from our study suggest some differences in responses to FOPL according to the level of education, with N-S appearing better in those with lower education levels. However, this was not the case for all foods, and as we did not statistically test differences, it warrants further investigation.
The findings from this study support FOPLs as a policy intervention to improve British consumers’ ability to understand the healthiness of food products. Our findings provide evidence that both the MTL and N-S FOPLs are likely to be most effective at improving knowledge. Whilst there was some evidence that N-S had the largest effects, the difference between MTL and N-S was relatively small and not significant for individual foods.
