The effects of a sugar-sweetened beverage tax and a nutrient profiling tax based on Nutri-Score on consumer food purchases in a virtual supermarket: a randomised controlled trial.

Michelle Eykelenboom,Margreet R Olthof,Maartje P Poelman,Reina E Vellinga,Sanne K Djojosoeparto,Wilma E Waterlander,Carry M Renders,Ingrid Hm Steenhuis,Carlijn Bm Kamphuis,Maartje M Van Stralen

doi:10.1017/s1368980021004547

Abstract

To investigate the effects of a sugar-sweetened beverage (SSB) tax and a nutrient profiling tax on consumer food purchases in a virtual supermarket. A randomised controlled trial was conducted with a control condition with regular food prices (n 152), an SSB tax condition (n 130) and a nutrient profiling tax condition based on Nutri-Score (n 112). Participants completed a weekly grocery shop for their household. Primary outcome measures were SSB purchases (ordinal variable) and the overall healthiness of the total shopping basket (proportion of total unit food items classified as healthy). The secondary outcome measure was the energy (kcal) content of the total shopping basket. Data were analysed using regression analyses. Three-dimensional virtual supermarket. Dutch adults aged ≥18 years are being responsible for grocery shopping in their household (n 394). The SSB tax (OR = 1·62, (95 % CI 1·03, 2·54)) and the nutrient profiling tax (OR = 1·88, (95 %CI 1·17, 3·02)) increased the likelihood of being in a lower-level category of SSB purchases. The overall healthiness of the total shopping basket was higher (+2·7 percent point, (95 % CI 0·1, 5·3)), and the energy content was lower (-3301 kcal, (95 % CI -6425, -177)) for participants in the nutrient profiling tax condition than for those in the control condition. The SSB tax did not affect the overall healthiness and energy content of the total shopping basket (P > 0·05). A nutrient profiling tax targeting a wide range of foods and beverages with a low nutritional quality seems to have larger beneficial effects on consumer food purchases than taxation of SSB alone.

Highlights

As part of the European Policy Evaluation Network[23], the aim of this study was to investigate the effects of an sugar-sweetened beverage (SSB) tax based on a scheme similar to an enacted European SSB tax – the UK’s Soft Drink Industry Levy (SDIL) – and a nutrient profiling tax based on Nutri-Score on SSB purchases and healthy food purchases in a virtual supermarket setting
This study aimed to investigate the effects of an SSB tax and a nutrient profiling tax based on Nutri-Score on SSB purchases and healthy food purchases in a virtual supermarket
We demonstrated that the nutrient profiling tax is effective in decreasing SSB purchases as well as in increasing the overall healthiness and decreasing the energy content of the total weekly food shopping basket; in case of an SSB tax, effects were only observed on SSB purchases

Summary

Methods

Study design A randomised controlled trial was conducted in which participants were randomly assigned to one of the following conditions in the virtual supermarket: (i) a control condition with regular food prices; (ii) an experimental condition with a two-tiered SSB tax or (iii) an experimental condition with a nutrient profiling tax based on Nutri-Score[22]. In the Netherlands, regular food prices include a value-added tax rate of 9 % that applies to all food and beverage products[24]. A consumption tax of €0·0883/l applies to fruit and vegetable juices, soft drinks and mineral water, with no distinction between SSB and sugar-free beverages (e.g. water or non-caloric sweetened beverages)(25). The notification was tailored to the condition; ‘In the virtual supermarket, beverages high in sugar are taxed’ or ‘In the virtual supermarket, unhealthy products high in sugar, fat and/or salt (such as biscuits, sweets, snacks and soft drinks) are taxed’. Participants in the control condition did not receive such a notification

Results

Discussion

Conclusion