Interpretation and implications of findings

Our study builds on previous work measuring noticing and using nutrition information with a multi-country comparison of jurisdictions where energy labelling on menus was mandatory compared to where it was not. Jurisdictions with mandatory nutrition labelling policies had higher rates of noticing nutrition information, ordering something different, eating less of what was ordered and changing restaurants due to nutrition information availability. However, there were no differences between policy groups in frequency of eating out at restaurants. This suggests menu labels may affect behaviour within restaurants, but do not affect consumers’ decision of whether or not to eat at a restaurant.

Most importantly, these results suggest that mandatory menu labelling policies may be improving behaviours associated with menu labelling at restaurants when comparing jurisdictions with and without mandatory menu labelling policies. These changes are according to our proposed mechanism involving noticing, using and types of use all leading to changes in energy consumed. There is evidence for the link between noticing labels and behaviour change. For example, noticing other types of labels such as traffic light labels has been found to be associated with healthier items purchased^{(Reference Sonnenberg, Gelsomin and Levy39)}. Mandatory menu labelling policies have increased noticing and use of nutrition information in other contexts, but more evidence is needed to understand whether these findings are consistent for older age groups and in other countries and population subgroups^{(Reference Goodman, Vanderlee and White33)}. More recent evidence from the USA suggests the small-to-moderate reductions in energy purchased may diminish over time, potentially reducing the long term public health impact of energy labels. The present study found significant differences between mandatory and non-mandatory menu labelling jurisdictions for five out of six behavioural outcomes measured, which could potentially lead to improved diets across large populations.

Although noticing and use of nutrition information was greater in jurisdictions with mandatory labelling policies, estimates were relatively low (21·2 % noticing and 10·6 % using nutrition information), and the differences in behaviours associated with menu labelling are modest. However, these differences could still be meaningful for health when they include millions of people. To improve public health, there may be ways to augment the effects of menu labelling policies. First, menu labelling interventions may be optimised by further helping people notice nutrition information – for example by making the information more prominent via increased size or visual salience^{(Reference Peschel, Orquin and Mueller Loose40)}. Second, interventions could help people use nutrition information by including associated messaging such as choosing an option with lower energy content to benefit health. For example, evaluative labels may be easier to interpret than numerical labels^{(Reference Thorndike, Sonnenberg and Riis41)}, and adding a recommended daily energy intake alongside menu labels maybe increase their effects^{(Reference Roberto, Larsen and Agnew42)}. Previous work has also found that motivation to use nutrition information may be a more important barrier than mere nutrition knowledge^{(Reference Grunert, Fernández-Celemín and Wills43)}. Third, additional policies are needed to have a large impact on diets across populations. Mandatory menu labelling may be a component of an effective obesity reduction strategy, but it is unlikely to achieve government targets to reduce obesity without complementary policies as eating behaviours are influenced by numerous complex factors beyond individual decision-making processes.

Although our study suggests mandatory menu labelling policies may play a role in reducing energy consumption out of home, other mechanisms of action may have more important effects, and mandatory labelling policies alone may not be enough to greatly reduce energy intake out of home across large populations. Additional messaging about how to use energy information alongside mandatory menu labelling policies may augment consumers noticing and ability to use this information to make healthier food choices when eating outside the home. People may also lack guidance regarding how to understand and use nutrition information to eat healthier and ultimately improve their health. Some jurisdictions such as New York City have tried to supplement mandated energy information posted on chain restaurant menus by adding recommended energy intake per day or per meal, but with no effect^{(Reference Downs, Wisdom and Wansink25)}. Future work is needed to determine whether other policies that reduce energy consumed out of home are more effective than menu labelling, and more research is needed to understand whether the sociodemographic differences in self-reported behaviours found in this study also exist for dietary intake. Menu labelling may also spur reformulation of products to lower energy or healthier forms by reducing nutrients of concern. However, energy labelling in large chain restaurants was associated with minimal changes in energy content of menu items, primarily consisting of the introduction of new lower energy items^{(Reference Grummon, Petimar and Soto44)}.

Differences between policy groups by sociodemographic characteristics

In addition to estimating the differences between policy groups for each of the six behavioural outcomes, we found several differences between policy groups by demographic characteristics. Examining differences between policy groups by age, the youngest age group, aged 18–24 were the mostly likely to eat less of their order compared to other age groups. Among United Kingdom diners at catering establishments, younger groups were more interested in menu labelling than older groups^{(Reference Mackison, Wrieden and Anderson45)}, and this greater interest could translate into greater use. On the other hand, the greatest differences for noticing and using menu labels were found for the middle and upper-middle age groups. Noticing and using nutrition information were more common for younger age groups living in No Policy jurisdictions, and differences between policy groups were larger for older groups. This finding is supported by a systematic review of nutrition labels on pre-packaged foods that found older adults were less likely to use nutrition labels than middle-aged and young adults^{(Reference Campos, Doxey and Hammond46)}. Our study similarly found low noticing and use of nutrition information among older age groups, but living in a Policy Present area reduced some of the disparity.

Examining the differences between policy groups by education, rates of noticing nutrition information, using nutrition information and changing restaurants were roughly equal in No Policy jurisdictions, but the increases were greater for higher education and majority ethnicity groups in Policy Present jurisdictions (Tables 5 and 6). Differences between policy groups for changing restaurants were also greater in the higher income adequacy group compared to the lower income adequacy group, and the higher income adequacy group was more likely to change restaurants in the Policy Present group (Table 7). This suggests that higher education and higher income groups may be more sensitive to changing restaurants within Policy Present jurisdictions. Indeed, higher comprehension and use of nutritional labels has been found to be associated with higher income and higher education^{(Reference Campos, Doxey and Hammond46)}. Higher education and higher income levels were associated with a greater likelihood of ordering something different, changing restaurants and eating at restaurants less often. The highest income level group was also the most likely to eat less of what they ordered due to noticing nutrition information. This is concordant with the majority of previous evidence which also suggests higher education and income levels are associated with greater use of nutrition labels^{(Reference Campos, Doxey and Hammond46)}. Although some other research has not found any convincing evidence of sociodemographic disparities in responses to menu labelling, the present results suggest that menu labelling policies, specifically those containing only numeric information, could potentially widen inequalities in healthy eating and therefore health^{(Reference Robinson, Polden and Langfield47,Reference Robinson, Boyland and Christiansen48)} . This insight suggests that other interventions may be needed to support lower education groups through mechanisms other than information-based policies that require significant cognitive demand on individuals. There is evidence that labels can be designed to avoid widening disparities between socio-economic groups. Other types of labels, such as warning labels, may be of greater use for people of low income or literacy, thereby reducing disparities^{(Reference Hall, Lazard and Grummon49)}. Therefore, our results suggest the association between label design and socio-economic disparities should be considered when designing labels for real world policies.

The difference between policy groups was greater in the majority ethnicity group compared to the minority ethnicity group for ordering something different, but these differences were primarily due to high rates of ordering something different for minority groups in No Policy jurisdictions (Table 5). The rates of ordering something different in No Policy jurisdictions for minority groups were closer to the rates found in Policy Present jurisdictions for both minority and majority groups. Previous work from the USA found Black or Hispanic participants were more likely to choose restaurants with menu labelling and to use caloric information compared to White participants^{(Reference Bleich and Pollack50)}. A similar pattern could explain our findings of greater ordering something different in No Policy jurisdictions if minority groups are more likely to seek restaurants that have menu labelling compared to majority groups. These findings suggest that there may be limited additional benefit of mandatory menu labelling policies for minorities if they already using nutrition information at a greater rate than in voluntary jurisdictions. However, further work is needed to determine whether this pattern exists across other populations. Overall, these differential effects of menu labelling in restaurants across groups suggest complementary policies may be needed to support healthy eating and reduce inequalities across more vulnerable socio-economic groups.

Strengths and limitations

To our knowledge, this is the first multi-country examination of national and state/province-level menu labelling policies and associated behaviours. Using the same survey questions across intervention and comparison policy jurisdictions allows for between-country comparisons that are otherwise more challenging to do between countries with limited capacity to conduct routine national diet surveys^{(Reference Hammond, Vanderlee and White27)}. Thus, these results may help provide more generalisable evidence for the effects of menu labelling on self-reported eating behaviours. Weighted IFPS estimates are close to the sociodemographic distributions in the countries studied, although there was a lower recruitment of low education participants from Mexico^{(Reference Hammond, Vanderlee and White27)}. Finally, the large study sample of nearly twenty thousand participants increases power to detect differences between policy groups.

Our study does have limitations as we cannot determine the degree to which self-reported behavioural changes translate to changes in dietary intake, obesity or other health outcomes. There are also some variations in menu labelling policies within our Policy Present and No Policy groups. Although we were able to categorise jurisdictions into either Policy Present or No Policy groups, the mandatory policies in Canada, Australia and the USA are not exactly the same – for example, businesses with twenty or more locations in Ontario, Canada, could refer to businesses with greater density of outlets compared to with twenty or more locations across the USA, given the different density of outlets required to meet the twenty outlet threshold in geographic areas of different size. Thus, our study has some challenges to consistency – variations of exposure (Policy Present in this study) do not differentially affect outcomes (behavioural measures in this study) – a core assumption of causal inference. The cross-sectional nature of a single data collection and a natural experimental design are more vulnerable to confounding bias than randomised controlled trials for demonstrating causal effects, and we cannot eliminate the possibility for residual confounding if some factor other than policy status is driving the differences between groups, such as country differences. Due to the single year of data used, we also cannot determine whether differences observed in 2019 are due to reverse causation: for example, if pre-policy rates of noticing and using menu labels were higher and thereby facilitated policy adoption. Finally, we did not examine all mechanisms through which menu labels could improve population health. Menu labels could improve health through pathways other than the behaviours examined here – for example through product reformulation – which could reduce energy intakes.