Impact case study database

The University of Oxford’s research into health-related food and drink taxes has had significant international impact, contributing directly to the introduction of sugary drinks taxes in Mexico (2014), the UK (2018) and Ireland (2018) and influencing the introduction of similar taxes around the world. By December 2020, according to the World Cancer Research Fund, there were sugary drinks taxes in 38 countries [A].

Mexico: For over 20 years the University of Oxford has worked closely with researchers in Mexico including (during the period 2011 - 2018) the Undersecretary of Prevention and Health Promotion of the Mexican Ministry of Health. As testified by the Undersecretary, this close collaboration and discussion of the research evidence meant that ‘ even before results were published, the findings from the Mexico City Prospective Study influenced health policy decision making in matters related to non-communicable diseases such as diabetes, hypertension and obesity. In particular, the study influenced both the decision in 2014 to introduce taxes on sugary drinks and the declaration in 2016 of diabetes and obesity as epidemiologic emergencies (the first time this had been done for non-communicable diseases)’ [B]. The 2016 declaration led to the introduction of a wide range of health policies aimed at tackling and treating obesity and diabetes, including healthy eating, on-pack labelling, medical check-ups and physical activity. The introduction of the sugary drinks tax in Mexico was the catalyst for similar adoptions by other countries, as acknowledged by international agencies: ‘The passage, implementation and subsequent evaluation of Mexico’s SSB (Sugar sweetened beverage) tax (implemented 1 January 2014) acted as a tipping point for global action’, World Cancer Research Fund International [C].

UK: The introduction of a sugary drinks tax in Mexico led to the proposal among UK policy makers for a similar tax for Britain. One of the UK modelling studies conducted by Oxford University [4] was cited in Public Health England (PHE)’s policy document ‘ Sugar reduction, Responding to the challenge’ [D] (June 2014) In their subsequent report ‘ Sugar Reduction, The evidence for action’ [D] (October 2015) PHE specifically recommended the introduction of ‘ a price increase of a minimum of 10-20% on high sugar products through the use of a tax or levy such as on full sugar soft drinks, based on the emerging evidence of the impact of such measures in other countries.’

The recommendation from PHE was discussed during the UK Parliamentary Health Select Committee’s inquiry into childhood obesity in October 2015. Professors Susan Jebb and Peter Scarborough presented oral evidence to the committee, which included discussing the evidence from Mexico which indicated that such a tax would be effective in the UK. The resulting report ‘ Childhood obesity – brave and bold action’ (November 2015) [E] recommended a sugary drinks tax in the UK and stated that ‘ The evidence suggests that increasing the price of high sugar products by 10–20% or more through the use of a tax or levy would be likely to have an effect on purchasing behaviour and therefore sugar consumption at least in the short term’. During a debate in Parliament on this recommendation (November 2015), the Chair of the Select Committee (Sarah Wollaston MP), said, ‘ We know from the experience in Mexico that a 10% levy on sugary drinks has led to a 6% reduction in consumption’ [F].

This report had a direct impact on the opinions of MPs, who then spoke in support of the tax in Parliament in November 2015 [F]:

• ‘During the Select Committee’s inquiry, we heard some compelling evidence calling for brave and bold action on obesity…A few months ago I was against a sugary drinks tax, because I am against extra taxation, but the compelling evidence that we heard changed my mind.’

MP for Erewash, Maggie Throup

• ‘Following the introduction of the tax on sugar-sweetened drinks (in Mexico), purchases were reduced by 6% in 2014. We need to be aware of the evidence showing that a tax will actually reduce the purchases of sugary drinks’, MP for Heywood and Middleton, Liz McInnes

• ‘As I have looked into the issue more and more, I have reached the position where I find the evidence compelling: something needs to be done.’ MP for St Austell and Newquay, Steve Double.

This increased political support, coupled with greater public acceptance (described below), led to the announcement of the UK Soft Drinks Industry Levy (SDIL) in March 2016.

Ireland: The publication of the modelling studies [2] and [3] led to the researchers being commissioned by the Irish Government’s Department of Health in 2011 to carry out a modelling study of a 10% tax. This was incorporated within a health impact assessment (HIA) published by the Irish Institute of Public Health in 2012 and then subsequently in BMC Public Health [6]. This led to a recommendation by the Department of Health for the introduction of ‘ a graded tax on pre-packaged [sugar-sweetened soft drinks] on sale in Ireland’ in 2016 [G]. As supporting evidence, the Department of Health referenced the HIA: ‘[the HIA] found evidence that ‘taxation could work to reduce overweight and obesity’ depending on the level of tax imposed…[and] concluded that a 10% tax on the price of SSDs [sugary drinks] would reduce obesity by 1.25% among adults in Ireland’ [G]. The recommendation for a tax was acted upon by the Irish Government, which introduced a tax in April 2018.

International: The success of the tax on sugary drinks in Mexico influenced WHO’s stance on using fiscal measures to reduce sugar consumption [H]. In their influential report ‘ Tackling NCDs (Noncommunicable Diseases): Best Buys’ [H], WHO includes as a ‘best buy’ policy recommendation: ‘ Reduce sugar consumption through effective taxation on sugar-sweetened beverages.’ This report has contributed to the roll out of sugary drinks taxation policies worldwide. The World Cancer Research Fund tracks international food policies and currently notes sugary drinks taxes 39 countries including 10 in Europe [A]. Of these, 37 have been implemented since the introduction of the tax in Mexico in 2014, with many countries citing evidence of the link between sugar consumption, weight gain, overweight and obesity as a driving factor.

The work of the researchers resulted in extensive media attention and public discussion of the issue. For example, Professor Mike Rayner appeared in BBC2’s Trust Me I’m a Doctor (2014) in a feature exploring the health impacts of excess sugar. Professor Rayner was also interviewed in Jamie Oliver’s Sugar Rush Documentary (2015) which was viewed by over 1.2M people in the UK. The celebrity chef Jamie Oliver subsequently went on to be a key advocate for a sugary drinks tax in the UK, contributing to the adoption of the tax by the UK Government and public acceptance. Increased general awareness of the health impacts of sugar led to greater public acceptance of a tax on sugary drinks. In 2013 only about 36% of people in the UK supported the introduction of a tax on sugary drinks. By 2015 this had risen to around 58%, but by March 2016, just after the sugary drinks tax had been announced, 69% supported the introduction [I].

The SDIL succeeded in prompting widespread product reformulation. All major brands of soft drinks (including supermarket brands) launched new sugar-free versions. This increased access to low-sugar drinks and allowed consumers to reduce their sugar consumption without compromising their preferences or brand loyalties. In an evaluation of the UK SDIL, the Oxford University researchers demonstrated that the proportion of soft drinks containing >5g/100ml of sugar available on the UK market fell from 49% in 2015 to 15% in 2019 [J]. In addition, the majority of new products had a sugar level between 4.5 and 5.0 g per 100 mL, suggesting they the 5.0g threshold of the levy had guided the reformulation. In contrast, drinks exempt from the SDIL (such as 100% fruit juice and milk-based drinks), saw no reduction in average sugar content, reinforcing that the levy was the motivating factor for change [J].

A review by Public Health England (PHE) in October 2020 concluded that between 2015 and 2019 in England, there was a 43.7% reduction in the total sugar content per 100ml for retailer and manufacturer branded drinks subject to the SDIL [K]. This meant that although sales in all soft drinks increased by 14.9% during this time, the total sugar purchased per household from drinks subject to the SDIL decreased across all socio-economic groups (between 38.5% - 35.1%). Reduced purchasing of sugar ultimately led to reduced sugar consumption. An analysis conducted by the University of Oxford researchers found that between 2015 and 2018, total sugar consumption from soft drinks declined by 29% despite soft drink consumption rising during this period. Further preliminary results of the evaluation of the levy indicate that compared to the pre-announcement, the amount of sugar purchased in drinks by a household each week reduced by 29.5g (9.8%) one year after the introduction of the levy. The 2017 modelling study [5] suggested that the observed reformulation and reduced sugar consumption due to the levy will ultimately result in 140,000 fewer people with obesity and 19,000 fewer incident cases of type 2 diabetes per year in the UK, as well as nearly 270,000 fewer decayed, missing, or filled teeth annually. According to PHE data, the number of 0-5 year olds being admitted to hospital in England for tooth extractions fell by 20.9% between 2014/15 (16,591) and 2018/19 (13,120). Between April-October 2018, the levy raised almost GBP154,000,000 for programmes to support pupil health and well-being, including primary physical education and the Healthy Pupils Capital Fund.

An evaluation of the tax in Mexico (introduced in 2014) shows that purchases of taxed beverages fell by 7.6%, between 2014 and 2016 [L]. In a modelling study, the Oxford University researchers estimated that this would lead to a projected reduction in new cases of diabetes by 189,300 for the time period 2013 to 2022, amounting to total savings between USD769million to USD1.2billion in direct healthcare costs.