Changes in soft drinks purchased by British households associated with the UK soft drinks industry levy: controlled interrupted time series analysis.
BMJ (Clinical research ed.) 2021 ; 372: n254.
DOI : 10.1136/bmj.n254
PubMed ID : 33692200
PMCID : PMC7944367
To determine changes in household purchases of drinks and confectionery one year after implementation of the UK soft drinks industry levy (SDIL).
Controlled interrupted time series analysis.
Members of a panel of households reporting their purchasing on a weekly basis to a market research company (average weekly number of participants n=22 183), March 2014 to March 2019.
A two tiered tax levied on manufacturers of soft drinks, announced in March 2016 and implemented in April 2018. Drinks with ≥8 g sugar/100 mL (high tier) are taxed at £0.24/L and drinks with ≥5 to <8 g sugar/100 mL (low tier) are taxed at £0.18/L. Drinks with <5 g sugar/100 mL (no levy) are not taxed.
Absolute and relative differences in the volume of, and amount of sugar in, soft drinks categories, all soft drinks combined, alcohol, and confectionery purchased per household per week one year after implementation of the SDIL compared with trends before the announcement of the SDIL.
In March 2019, compared with the counterfactual estimated from pre-announcement trends, purchased volume of drinks in the high levy tier decreased by 155 mL (95% confidence interval 240.5 to 69.5 mL) per household per week, equivalent to 44.3% (95% confidence interval 59.9% to 28.7%), and sugar purchased in these drinks decreased by 18.0 g (95% confidence interval 32.3 to 3.6 g), or 45.9% (68.8% to 22.9%). Purchases of low tier drinks decreased by 177.3 mL (225.3 to 129.3 mL) per household per week, or 85.9% (95.1% to 76.7%), with a 12.5 g (15.4 to 9.5 g) reduction in sugar in these drinks, equivalent to 86.2% (94.2% to 78.1%). Despite no overall change in volume of no levy drinks purchased, there was an increase in sugar purchased of 15.3 g (12.6 to 17.9 g) per household per week, equivalent to 166.4% (94.2% to 238.5%). When all soft drinks were combined, the volume of drinks purchased did not change, but sugar decreased by 29.5 g (55.8 to 3.1 g), or 9.8% (17.9% to 1.8%). Purchases of confectionery and alcoholic drinks did not change.
Compared with trends before the SDIL was announced, one year after implementation, the volume of soft drinks purchased did not change. The amount of sugar in those drinks was 30 g, or 10%, lower per household per week-equivalent to one 250 mL serving of a low tier drink per person per week. The SDIL might benefit public health without harming industry.
People appear to be buying and consuming less sugar from soft drinks since the UK introduced a tax on sugary drinks, suggests research published by The BMJ.
The researchers found that overall sales of soft drinks have not changed. This, together with previous findings of no long term impact of the tax on soft drinks share price and domestic turnover, suggests that the drinks industry has not been hit financially as a result of the tax which was designed to improve public health.
High consumption of sugar sweetened beverages (SSBs) is associated with increased risk of tooth decay, obesity, type 2 diabetes and cardiovascular disease. As such, the World Health Organization recommends taxes on these drinks to try to reduce consumption.
The UK soft drinks industry levy (SDIL) is a two tiered tax levied on soft drinks manufacturers from April 2018 to encourage them to reduce the sugar content in their products.
Under the SDIL, drinks with more than 8 g sugar/100 mL (high tier) are taxed at £0.24/L and drinks with more than 5 g but less than 8 g sugar/100 mL (low tier) are taxed at £0.18/L. Drinks with less than 5 g of sugar/100 mL (no levy) are not taxed.
Although previous studies have explored the effect of consumer-facing SSB taxes, none have explored the effect of the implementation of the SDIL on purchases, taking existing trends in purchases into account.
To address this gap, a team of researchers led by University of Cambridge’s MRC Epidemiology Unit decided to examine changes in household purchases of drinks and confectionery before and after implementation of the SDIL.
They studied changes in the volume of, and amount of sugar in, household purchases of drinks in each levy tier, exempt drinks categories (including alcoholic drinks), and confectionery from two years before the announcement of the SDIL to one year after its implementation (March 2014 to March 2019).
Their findings are based on around 31 million purchases by an average of 22,183 households that recorded all food and drink brought into the home (including those ordered online and delivered) on a weekly basis during this period.
Compared with pre-announcement trends, the researchers found that purchased volume of drinks in the high levy tier decreased by 155 mL per household per week by March 2019, equivalent to 44%, and sugar purchased in these drinks decreased by 18 g or 46%.
Similarly, purchases of low tier drinks decreased by 177 mL per household per week, or 86%, with a 12.5 g reduction in sugar in these drinks, equivalent to 86%.
Despite no overall change in the volume of no levy drinks purchased, there was an increase in sugar purchased of 15 g per household per week, equivalent to 166%.
Overall, they show that compared with pre-announcement trends, the total volume of all taxed and untaxed soft drinks purchased did not change one year after implementation.
When all taxed and untaxed soft drinks were combined, the volume of drinks purchased did not change, but sugar purchased in these drinks decreased by around 30 g per household per week, or almost 10% - equivalent to three fewer teaspoons, or one 250 mL serving of a drink with 5 g sugar per 100 mL per person per week.
Purchases of confectionery and alcoholic drinks did not change.
The authors acknowledge some study limitations. For example, data only included purchases brought into homes, which could limit the generalisability of the findings.
However, the researchers used a large, nationally representative dataset, included a control category, and explored changes in two potential substitute categories – alcohol and confectionery.
As such, they say tiered SSB taxes such as the SDIL “might represent a benefit for public health (by reducing sugar purchased from soft drinks without substitution to confectionery and alcohol) without any commensurate harm to the soft drinks industry (by not affecting total volume of soft drinks purchased).”
These findings show that the UK’s sugar tax is working exactly as intended - and offer lessons for other countries exploring strategic regulatory options to promote healthier diets, say researchers at the George Institute for Global Health, in a linked editorial.
They discuss ways in which SSB taxes have been used to improve health and say there is opportunity to strengthen regulation further. For example, to include thresholds for taxation that lower progressively over time to encourage ongoing sugar reduction.
Finally, they point out that as the world moves towards policies that promote healthier and more sustainable diets, “the challenge is to design regulations that improve nutritional quality and reduce the environmental impact of the foods we eat.”
There is potential here to deliver not only health benefits but also benefits for the planet and all those whose lives depend on it now, and for future generations,” they conclude.