Grounded in a ‘systems approach’, the SDIL Evaluation aims to examine:
- whether, how and for whom the levy has an effect on health
- the process by which the tax came about
- wider change in public, political, societal and industry attitudes to sugar and the SDIL over the period from 2014-2020.
What public health problem is the SDIL intended to tackle and how?
People who drink a lot of sugary drinks are more likely to develop tooth decay, obesity, diabetes and heart disease. Sugary drinks often contain lots of calories, and people can easily consume many calories from sugary drinks without feeling full. New UK guidance recommends that we reduce the amount of sugar we consume.
In 2015, Public Health England said a tax on sugary drinks would be a way to help us all consume less sugar. In March 2016 the UK Government announced a new levy in the budget, directed toward producers and importers of soft drinks that contain added sugar. Companies will have to pay 18p/L for drinks containing at least 5g of sugar per 100ml, and 24p/L for those with more than 8g per 100ml. The design and implementation of the levy was led by HM Revenue and Customs and HM Treasury. They consulted on the plan in August 2016 and it was included in the Finance Bill 2017, which received Royal Assent in May 2017. The SDIL will take effect from April 2018.The two year delay allows companies the time to reduce the amount of sugar in their drinks and avoid the tax. As no other country has tried this sort of tax, we don’t know what the effects will be.
What does the SDIL Evaluation Study plan to learn and how?
We have talked to people working in government, public health, drinks companies and health advocacy groups. They think the tax will have all sorts of effects, and not just on health. Our study will look at the most important of these effects, tracking how things change over time. Studying a wide range of effects of the tax will help us be more certain that the results we see are true. For example, if purchases of sugary drinks, tooth decay and childhood obesity all go down, and purchases of other drinks go up, this will increase our confidence that the tax has had a positive impact on health.
Because we want to study how things have been changing since before the tax was announced to after it is implemented, we will mostly rely on information that is regularly collected by other organisations. We will study:
- data from supermarkets to explore the effects of the tax on the price, sugar content, and range of drinks available
- market research data to track changes in purchases of drinks.
- purchases of confectionary to see if people switch from sugary drinks to sugary foods.
- government data to study effects of the tax on: diet, childhood obesity, and hospital admissions for tooth decay.
Modelling long term health and economic effects
Because any effects of the tax on what people eat and drink will take time to change their health, we will also use statistical methods (‘modelling’) to predict the effect of any changes in sugary drinks and diet on diseases and deaths 5-15 years later. From this, we will be able to predict potential financial savings for the NHS.
The tax’s effects might go beyond health. For instance, a healthier population should be more economically productive. Or people drinking fewer sugary drinks might mean fewer jobs in the food industry. We will use economics to predict the impacts of the tax on the whole UK economy.
Studying how different groups respond to the tax
We will also explore how different groups respond to the tax. We will conduct interviews and focus groups, and analyse newspapers and social media to explore how the public, politicians, public health professionals, and the sugary drinks industry feel about the tax. By studying these things over time we will be able to see, for example, whether any early opposition or support change over time.
In the UK, children drink more sugary drinks than adults. Obesity, heart disease, diabetes and tooth decay are more common in poorer people. Across all our work, we will look for any variations in effects between age groups, men and women, and levels of income.
The SDIL Evaluation Study is funded by the National Institute for Health Research’s Public Health Research Programme (Project number 16/130/01).
MRC Epidemiology Unit
- Prof Richard Smith
- Prof Steven Cummins
- Dr Marcus Keogh-Brown
- Dr Henning Tarp-Jensen
- Dr Laura Cornelsen
University of Bath
University of Oxford
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