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

Abstract

Background This study evaluates changes in sales of non-alcoholic beverages in Jamie’s Italian, a national chain of commercial restaurants in the UK, following the introduction of a £0.10 per-beverage levy on sugarsweetened beverages (SSBs) and supporting activity including beverage menu redesign, new products and establishment of a children’s health fund from levy proceeds. Methods We used an interrupted time series design to quantify changes in sales of non-alcoholic beverages 12 weeks and 6 months after implementation of the levy, using itemised electronic point of sale data. Main outcomes were number of SSBs and other nonalcoholic beverages sold per customer. Linear regression and multilevel random effects models, adjusting for seasonality and clustering, were used to investigate changes in SSB sales across all restaurants (n=37) and by tertiles of baseline restaurant SSB sales per customer. Results Compared with the prelevy period, the number of SSBs sold per customer declined by 11.0% (−17.3% to −4.3%) at 12 weeks and 9.3% (−15.2% to −3.2%) at 6months. For non-levied beverages, sales per customer of children’s fruit juice declined by 34.7% (−55.3% to −4.3%) at 12 weeks and 9.9% (−16.8% to −2.4%) at 6months. At 6months, sales per customer of fruit juice increased by 21.8% (14.0% to 30.2%) but sales of diet cola (−7.3%; −11.7% to −2.8%) and bottled waters (−6.5%; −11.0% to −1.7%) declined. Changes in sales were only observed in restaurants in the medium and high tertiles of baseline SSB sales per customer. Conclusions Introduction of a £0.10 levy on SSBs alongside complementary activities is associated with declines in SSB sales per customer in the short and medium term, particularly in restaurants with higher baseline sales of SSBs