Change in non-alcoholic beverage sales following a 10-pence levy on sugar-sweetened beverages within a national chain of restaurants in the UK: interrupted time series analysis of a natural experiment

Evaluating the impact of marketing interventions on sugar-free and sugar-sweetened soft drink sales and sugar purchases in a fast-food restaurant setting

BACKGROUND

Beverages high in added sugar, such as sugar-sweetened soft drinks, continue to be associated with various health issues. This study examines the effects of a manufacturer-initiated multicomponent intervention on the sales of sugar-free (SFD) and sugar-sweetened (SSD) soft drinks and the amount of sugar people purchase from soft drinks in a fast-food restaurant setting.

METHODS

A database of monthly sales data of soft drinks from January 2016 to December 2018 was obtained from three treatment and three control fast-food restaurants. A multicomponent intervention consisting of free coupons, point-of-purchase displays, a menu board, and two sugar-free replacements for sugar-sweetened soft drinks was introduced in August 2018 for five months in Western Sydney, Australia. A retrospective interrupted time series analysis was used to model the data and examine the effects of the interventions on SFD and SSD sales and their consequential impact on sugar purchases from soft drinks. The analyses were carried out for volume sales in litres and sugar in grams per millilitre of soft drinks sales. A comparison of these measures within the treatment site (pre- and post-intervention) and between sites (treatment and control) was conducted.

RESULTS

The interventions had a statistically significant impact on SFDs but not SSDs. On average, SFD sales in the treatment site were 56.75% higher than in the control site. Although SSD sales were lower in the treatment site, the difference with the control site was not statistically significant. The net reduction of 6.34% in the amount of sugar purchased from soft drinks between sites during the experimental period was attributed to the interventions.

CONCLUSIONS

The interventions significantly increased SFD sales and reduced sugar purchases in the short run. Aside from free coupons, the findings support the recommendation for fast food restaurants to nudge customers towards choosing SFDs through point-of-purchase displays and the replacement of popular SSDs with their SFD counterparts.

Assessing the impact of Hungary's public health product tax: an interrupted time series analysis

OBJECTIVES

Imposing taxes on unhealthy goods can generate income, raise people's health awareness, and eventually decrease the prevalence of chronic diseases. Our aim was to assess the impact of Hungary's public health product tax (PHPT) since its implementation in September 2011. Differences in purchasing habits between households with different income statuses were also compared.

METHODS

A retrospective, descriptive analysis of tax bases and income was carried out, and an interrupted time series analysis using the generalised least squares method was performed to examine the changes in trends regarding the purchase of taxable products before and after the implementation of the tax. The amount of tax base (in kilograms or litres), income (in HUF and EUR), and annual purchased quantity of food and beverage groups per household were assessed. Data were derived from the National Tax and Customs Administration of Hungary and the Hungarian Household Budget and Living Conditions Surveys. The study sample was composed of households who participated in the surveys (mean = 8,359, SD = 1,146) between 2006 and 2018.

RESULTS

The households' tax bases and incomes increased constantly (with a few exceptions). The total revenue was 19.49 billion HUF (67.37 million EUR) in 2012 and 59.19 billion HUF (168.55 million EUR) in 2020. However, the households' purchasing habits did not change as expected. A significant short-term decrease (between 2012 and 2013) in purchasing unhealthy goods was observed for three groups: soft drinks (p = 0.009), jams (p = 0.047), and fruit juices (p = 0.038). Only soft drinks showed a significant decreasing trend in the post-intervention period between 2012 and 2018 (p < 0.001).

CONCLUSIONS

We concluded that the PHPT did not decrease households' unhealthy food purchasing trend, although it has a positive effect as it can create revenue for health care and health-promoting programmes.

Outcomes Following Taxation of Sugar-Sweetened Beverages: A Systematic Review and Meta-analysis

Importance

More than 45 countries and several local jurisdictions have implemented sugar-sweetened beverage (SSB) taxes to improve nutrition and population health, and evidence on their outcomes to date is essential to inform policy discussions. Responding to this need, the World Health Organization commissioned a systematic literature review on the outcomes of fiscal policies, including SSB taxes.

Objective

To assess the associations of implemented SSB taxes with prices, sales, consumption, diet, body weight, product changes, unintended consequences, health, and pregnancy outcomes.

Data Sources

Searches of 8 bibliographic databases (Business Source Complete, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, CINAHL, EconLit, PsycINFO, PubMed, and Scopus) were performed from database inception through June 1, 2020, with no language or setting restrictions. Grey literature was assessed using 14 sources and government websites.

Study Selection

The review included primary studies of implemented SSB taxes.

Data Extraction and Synthesis

The review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. For prices, sales and consumption, results were meta-analyzed using a 3-level random-effects model. Study quality was assessed at the outcome level.

Main Outcomes and Measures

Tax pass-through rate for prices, percentage reduction in SSB demand, and price elasticity of demand for sales and consumption. Heterogeneity was assessed using τ2 and the I2 statistic.

Results

A total of 86 articles were eligible, with 62 studies contributing to the meta-analysis. The overall tax pass-through rate was 82% (95% CI, 66% to 98%; P < .001, I2 = 99%), suggesting tax undershifting. The demand for SSBs was highly sensitive to tax-induced price increases, with the price elasticity of demand of -1.59 (95% CI, -2.11 to -1.08; P < .001; I2 = 100%) and a mean reduction in SSB sales of 15% (95% CI, -20% to -9%; P < .001; I2 = 100%). There was no evidence of substitution to untaxed beverages, and changes in SSB consumption were not significant. The narrative synthesis found reformulation and reduced sugar content of taxed beverages for tiered taxes, cross-border shopping in most studies of local-level taxes, and no negative changes in employment. Data on the heterogeneity of SSB tax outcomes across subpopulations were limited.

Conclusions and Relevance

In this systematic review and meta-analysis of implemented SSB taxes worldwide, SSB taxes were associated with higher prices and lower sales of taxed beverages.

The effect of on-shelf sugar labeling on beverage sales in the supermarket: a comparative interrupted time series analysis of a natural experiment

BACKGROUND

Nutrition labels show potential in increasing healthy food and beverage purchases, but their effectiveness seems to depend on the type of label, the targeted food category and the setting, and evidence on their impact in real-world settings is limited. The aim of this study was to evaluate the effectiveness of an industry-designed on-shelf sugar label on the sales of beverages with no, low, medium and high sugar content implemented within a real-world supermarket.

METHODS

In week 17 of 2019, on-shelf sugar labels were implemented by a Dutch supermarket chain. Non-alcoholic beverages were classified using a traffic-light labeling system and included the beverage categories "green" for sugar free (< 1.25 g/250 ml), "blue" for low sugar (1.25-6.24 g/250 ml), "yellow" for medium sugar (6.25-13.5 g/250 ml) and "amber" for high sugar (> 13.5 g/250 ml). Store-level data on beverage sales and revenue from 41 randomly selected supermarkets for 13 weeks pre-implementation and 21 weeks post-implementation were used for analysis. In total, 30 stores implemented the on-shelf sugar labels by week 17, and the 11 stores that had not were used as comparisons. Outcome measures were differences in the number of beverages sold in the four label categories and the total revenue from beverage sales in implementation stores relative to comparison stores. Analyses were conducted using a multiple-group Interrupted Time Series Approach. Results of individual store data were combined using random effect meta-analyses.

RESULTS

At the end of the intervention period, the changes in sales of beverages with green (B 3.4, 95%CI -0.3; 7.0), blue (B 0.0, 95%CI -0.6; 0.7), yellow (B 1.3, 95%CI -0.9; 3.5), and amber (B 0.9, 95%CI -5.5; 7.3) labels were not significantly different between intervention and comparison stores. The changes in total revenues for beverages at the end of the intervention period were also not significantly different between intervention and comparison stores.

CONCLUSION

The implementation of an on-shelf sugar labeling system did not significantly decrease unhealthy beverage sales or significantly increase healthier beverage sales. Nutrition labeling initiatives combined with complementary strategies, such as pricing strategies or other healthy food nudging approaches, should be considered to promote healthier beverage purchases.

Exploring the main and moderating effects of individual-level characteristics on consumer responses to sugar taxes and front-of-pack nutrition labels in an experimental marketplace

INTERVENTION

This study examined whether the impacts of sugar taxes and front-of-pack (FOP) nutrition labels differ across socio-demographic subgroups.

RESEARCH QUESTION

What are the main and moderating effects of individual-level characteristics on the nutrient content of participants' purchases in response to varying taxation levels and FOP labels?

METHODS

Data from an experimental marketplace were analyzed. A sample of 3584 Canadians aged 13 years and older received $5 to purchase an item from a selection of 20 beverages and 20 snack foods. Participants were shown products with one of five FOP labels and completed eight within-subject purchasing tasks with different tax conditions. Linear mixed models were used to estimate the main and moderating effects of 11 individual-level variables on the sugars, sodium, saturated fats, and calorie content of participants' purchases.

RESULTS

Participants who were younger, male, and more frequent consumers of sugary drinks purchased products containing more sugars, sodium, saturated fats, and calories. Sex and age moderated the relationship between tax condition and sugars or calories purchased: female participants were more responsive than males to a tax that included fruit juice, and younger participants were more responsive to all sugar tax conditions than older participants. Reported thirst and education level also moderated the relationship between tax condition and calories purchased. No individual-level characteristics moderated the effects of FOP labels.

CONCLUSION

A small proportion (7 of 176) of the moderating effects tested in this study were significant. Sugar taxes and FOP labelling policies may therefore produce similar effects across key socio-demographic groups.

Environmental Interventions to Reduce the Consumption of Sugar-Sweetened Beverages: Abridged Cochrane Systematic Review

BACKGROUND

Regular consumption of sugar-sweetened beverages (SSB) can increase the risk for obesity, type 2 diabetes, cardiovascular disease, and dental caries. Interventions that alter the physical or social environment in which individuals make beverage choices have been proposed to reduce the consumption of SSB.

METHODS

We included randomised controlled, non-randomised controlled, and interrupted time series studies on environmental interventions, with or without behavioural co-interventions, implemented in real-world settings, lasting at least 12 weeks, and including at least 40 individuals. Studies on the taxation of SSB were not included, as these are subject of a separate Cochrane review. We used standard Cochrane methods for data extraction, risk of bias assessment, and evidence grading and synthesis. Searches were updated to January 24, 2018.

RESULTS

We identified 14,488 unique records and assessed 1,030 full texts for eligibility. We included 58 studies comprising a total of 1,180,096 participants and a median length of follow-up of 10 months. We found moderate-certainty evidence for consistent associations with decreases in SSB consumption or sales for the following interventions: traffic light labelling, price increases on SSB, in-store promotion of healthier beverages in supermarkets, government food benefit programs with incentives for purchasing fruits and vegetables and restrictions on SSB purchases, multi-component community campaigns focused on SSB, and interventions improving the availability of low-calorie beverages in the home environment. For the remaining interventions we found low- to very-low-certainty evidence for associations showing varying degrees of consistency.

CONCLUSIONS

With observed benefits outweighing observed harms, we suggest that environmental interventions to reduce the consumption of SSB be considered as part of a wider set of measures to improve population-level nutrition. Implementation should be accompanied by evaluations using appropriate methods. Future studies should examine population-level effects of interventions suitable for large-scale implementation, and interventions and settings not yet studied thoroughly.

Using natural experiments to improve public health evidence: a review of context and utility for obesity prevention

Background

Natural experiments are increasingly valued as a way to assess the health impact of health and non-health interventions when planned controlled experimental research designs may be infeasible or inappropriate to implement. This study sought to investigate the value of natural experiments by exploring how they have been used in practice. The study focused on obesity prevention research as one complex programme area for applying natural experiment studies.

Methods

A literature search sought obesity prevention research from January 1997 to December 2017 and identified 46 population health studies that self-described as a natural experiment.

Results

The majority of studies identified were published in the last 5 years, illustrating a more recent adoption of such opportunities. The majority of studies were evaluations of the impact of policies (n = 19), such as assessing changes to food labelling, food advertising or taxation on diet and obesity outcomes, or were built environment interventions (n = 17), such as the impact of built infrastructure on physical activity or access to healthy food. Research designs included quasi-experimental, pre-experimental and non-experimental methods. Few studies applied rigorous research designs to establish stronger causal inference, such as multiple pre/post measures, time series designs or comparison of change against an unexposed group. In general, researchers employed techniques to enhance the study utility but often were limited in the use of more rigorous study designs by ethical considerations and/or the particular context of the intervention.

Conclusion

Greater recognition of the utility and versatility of natural experiments in generating evidence for complex health issues like obesity prevention is needed. This review suggests that natural experiments may be underutilised as an approach for providing evidence of the effects of interventions, particularly for evaluating health outcomes of interventions when unexpected opportunities to gather evidence arise.

What role should the commercial food system play in promoting health through better diet?

Martin White and coauthors consider that the commercial food system has the potential to show leadership and support for dietary public health, but systemic change is needed first and this is likely to require governmental action

Impact of the announcement and implementation of the UK Soft Drinks Industry Levy on sugar content, price, product size and number of available soft drinks in the UK, 2015-19: A controlled interrupted time series analysis

BACKGROUND

Dietary sugar, especially in liquid form, increases risk of dental caries, adiposity, and type 2 diabetes. The United Kingdom Soft Drinks Industry Levy (SDIL) was announced in March 2016 and implemented in April 2018 and charges manufacturers and importers at £0.24 per litre for drinks with over 8 g sugar per 100 mL (high levy category), £0.18 per litre for drinks with 5 to 8 g sugar per 100 mL (low levy category), and no charge for drinks with less than 5 g sugar per 100 mL (no levy category). Fruit juices and milk-based drinks are exempt. We measured the impact of the SDIL on price, product size, number of soft drinks on the marketplace, and the proportion of drinks over the lower levy threshold of 5 g sugar per 100 mL.

METHODS AND FINDINGS

We analysed data on a total of 209,637 observations of soft drinks over 85 time points between September 2015 and February 2019, collected from the websites of the leading supermarkets in the UK. The data set was structured as a repeat cross-sectional study. We used controlled interrupted time series to assess the impact of the SDIL on changes in level and slope for the 4 outcome variables. Equivalent models were run for potentially levy-eligible drink categories ('intervention' drinks) and levy-exempt fruit juices and milk-based drinks ('control' drinks). Observed results were compared with counterfactual scenarios based on extrapolation of pre-SDIL trends. We found that in February 2019, the proportion of intervention drinks over the lower levy sugar threshold had fallen by 33.8 percentage points (95% CI: 33.3-34.4, p < 0.001). The price of intervention drinks in the high levy category had risen by £0.075 (£0.037-0.115, p < 0.001) per litre-a 31% pass through rate-whilst prices of intervention drinks in the low levy category and no levy category had fallen and risen by smaller amounts, respectively. Whilst the product size of branded high levy and low levy drinks barely changed after implementation of the SDIL (-7 mL [-23 to 11 mL] and 16 mL [6-27ml], respectively), there were large changes to product size of own-brand drinks with an increase of 172 mL (133-214 mL) for high levy drinks and a decrease of 141 mL (111-170 mL) for low levy drinks. The number of available drinks that were in the high levy category when the SDIL was announced was reduced by 3 (-6 to 12) by the implementation of the SDIL. Equivalent models for control drinks provided little evidence of impact of the SDIL. These results are not sales weighted, so do not give an account of how sugar consumption from drinks may have changed over the time period.

CONCLUSIONS

The results suggest that the SDIL incentivised many manufacturers to reduce sugar in soft drinks. Some of the cost of the levy to manufacturers and importers was passed on to consumers as higher prices but not always on targeted drinks. These changes could reduce population exposure to liquid sugars and associated health risks.

Taxation of sugar sweetened beverages and unhealthy foods: a qualitative study of key opinion leaders' views

Background

Fiscal policies to fight obesity such as taxation of unhealthy foods or sugar-sweetened beverages (SSBs) have gained considerable attention in recent years. Many studies modelling the impact of various magnitudes of taxes on SSB purchasing and their potential effects on various health outcomes have been published; however, legislation and implementation of such taxes have encountered many obstacles in the countries that have implemented them to date. We investigated the perceptions and views of key opinion leaders, policy makers and various other Israeli stakeholders on taxation of SSBs and unhealthy snacks. We also evaluated the challenges and barriers that may be expected for initiating such a policy.

Methods

A qualitative study based on 39 in-depth interviews with Israeli stakeholders in the fields of health, nutrition, economics, public advocacy and policymaking.

Results

All stakeholders viewed obesity as a combined societal and personal issue that should be under government responsibility. Only stakeholders from economic sectors thought that taxation of SSBs and unhealthy snacks would reduce their consumption, while the prevailing notion among non-economists was that such a tax would not be acceptable because the higher price would not decrease consumption. Concerns were raised that the tax would mostly affect individuals from low socioeconomic backgrounds. Some of the stakeholders indicated that they would support such a tax only if its revenue would be directed to specific causes such as health-promoting plans. Potential barriers to taxation include: opposition of various sectors, technical and bureaucratic obstacles impeding tax implementation, difficulties in defining which products to tax, and opposition of the treasury to earmark tax revenue for health education.

Conclusions

Taxation should be a part of a multipronged strategy rather than a sole measure for fighting obesity. Dedicating tax revenues to specific predefined causes should be considered, particularly towards health promotion activities, obesity treatment and prevention, education, and subsidies of healthy food.

The impact of a local sugar sweetened beverage health promotion and price increase on sales in public leisure centre facilities

BACKGROUND

We aimed to evaluate the impact of a local sugar sweetened beverages (SSB) health promotion and 20p price increase in leisure centre venues and estimate the impact on consumption.

METHOD

Monthly cold drinks sales data and attendance at leisure centres across the city of Sheffield were analysed over the period January 2015-July 2017. Interrupted time-series methods were employed to estimate changes in consumption per attendance of SSB and non-SSB cold drinks following the introduction of the SSB policy from August 2016 adjusting for seasonal variation and autocorrelation. SSB price elasticities were estimated with fixed effects log-log models by SSB product type (soda can, soda bottle, soda post mix, energy drinks, juice from concentrate).

FINDINGS

We estimated a 31% (95% CI 4%, 59%) reduction in units of SSB sold per attendance in the year since the policy was introduced. We did not observe substitution effects to fruit juice or water but found sales of other artificially sweetened non-SSB products increased by 27% (95% CI 6%, 47%) after the introduction of the tax. Price elasticity analysis identified that a 1% increase in price alongside health promotion leads to a 3.8% (95% CI 3.1% 4.4%) decrease in demand for SSB's. Price elasticity of demand was highest for child friendly and high caffeine energy drinks.

INTERPRETATION

Demand for SSB drinks at leisure centre venues is highly responsive to the policy, particularly for child-friendly and high caffeine energy drinks, compared with other SSB tax policy evaluations. The policy also increased purchases of carbonated non-SSB.