Evaluating sugar-sweetened beverage tax effects: online price and sales data from grocers in Canada

Newfoundland and Labrador (NL) introduced Canada's first sugar-sweetened beverage (SSB) tax in September 2022. Compared with national averages, NL has higher intakes of SSBs, lower intakes of plain water and milk, with higher rates of overweight and obesity and diabetes. Taxing SSBs is a recommended intervention but real-world effectiveness of SSB taxes requires more investigation. We evaluated changes in weekly beverage prices and sales pre- and post-tax implementation, comparing NL (intervention) to non-tax regions in Canada (control). We used a controlled interrupted time series to evaluate prices from grocery store websites 3 months pre- and post-tax. We observed no differences-in-differences in the intercept [β = -0.024, 95% confidence interval (CI) -0.15-0.10, P = .70] or slope (β = 0.00, 95% CI -0.02-0.02, P = .99) of price changes. We used a repeat cross-sectional study to compare total annual sales of beverage categories in the year pre- and post-tax. Per capita sales in litres of taxable SSB decreased more in NL (-11.6%) than non-tax regions (-6.7%). Per capita sales of diet beverages (+4.4%) and unsweetened water (+2.2%) increased in NL. The NL SSB tax had no immediate impact on retail prices of taxable SSBs measured on product selection pages on grocery websites. Beverage purchasing shifted in NL since the SSB tax start date, however, it is difficult to isolate the impact of the SSB tax from broader market trends or other influencing factors. Long-term evaluation of the NL SSB tax is needed.