Evidence is sweetBMJ 2019; 366 doi: https://doi.org/10.1136/bmj.l4617 (Published 11 July 2019) Cite this as: BMJ 2019;366:l4617
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The Editorial reads: ‘Boris Johnson says he is concerned about their disproportionate effect on poor people. He also wants to base the UK’s tax policy “on clear evidence.” If so, all of us who want to improve the public’s health can rest easy: the accumulating evidence in favour of such taxes is becoming hard to counter.’
As the editorial indicates, there is a now a compelling body of research showing the damage caused by excessive intake of sugar and of sugary drinks in particular. There is also a compelling body of research showing that taxes on sugary drinks are effective in reducing sugar consumption by diverting consumers away from buying high sugar soft drinks towards buying low and no sugar soft drinks. This connection is fundamentally important from a public health perspective, because reduced sugar consumption offers clear health benefits. This evidence answers part of Boris Johnson’s point: “we should look at how effective the so-called ‘sin taxes’ really are, and if they actually change behaviour,” as quoted in the Guardian . Sugary drinks taxes certainly do change behaviour in a positive way for public health.
However, the reported evidence so far has not addressed the second aspect raised by Boris Johnson that sugary drinks taxes “clobber those who can least afford it” . Unfortunately, the analysis in my Independent Study Report  suggests that he is right, because the effect of the Soft Drinks Industry Levy (SDIL) was not just to raise the prices of high sugar drinks but also for low and no sugar drinks. I provide this evidence in relation to all product categories, but I focus in depth on supermarket sales of cola drinks as the largest category. I compared average prices for the year following compared to the year before the introduction of SDIL in April 2018. I found that average prices of high sugar cola increased by 38p per litre, up 43%, even though the Levy amount applied was only 24p per litre, while the average price of zero sugar cola increased by 8p per litre, up 10%, despite the Levy not applying to such drinks. Accordingly, even if consumers switch to buying zero sugar drinks, they still pay higher prices in the wake of SDIL.
My findings on the pricing effects are deeply troubling from a socio-economic perspective because they suggest that SDIL has been a very regressive tax. The new evidence just released by Public Health England  shows that households in lower socio-economic groups consume more high sugar and more low/zero sugar soft drinks than households in higher socio-economic groups. The implication of higher prices on both high sugar and low/zero sugar drinks is therefore a double whammy for lower income households, who are trapped into paying more regardless of their choice whether or not to switch to buying healthier soft drinks.
My analysis indicates that public health and the industry are real winners from the introduction of SDIL. Yet, consumers have lost out substantially in monetary terms. The estimated tax take is only £240m per year , but soft drinks sales have increased by £1.9bn a year in the past two years, of which sales of carbonates alone have increased by £1.5bn, against modest increases in drinks volume . Evidently, the industry has gained immensely from SDIL but consumers are deeply out of pocket.
I conclude that scope exists for extending SDIL to apply to other sugary products, notably sugary dairy drinks and milkshakes, to gain public health benefits from further reduced sugar consumption, but this carries the risk that consumers might well end up paying significantly higher prices even for low or zero sugar versions.
Is there a way to secure the public health benefits of SDIL but without clobbering lower-income households? Adam Briggs in this journal  makes a very valid suggestion for policymakers: “rather than scrapping a regressive tax aimed at improving population health, why not simply make the remaining tax system proportionately more progressive?”
 Heather Stewart, “'Sin taxes': Boris Johnson vows to review sugar levy,” Guardian, 3 July 2019 (https://www.theguardian.com/politics/2019/jul/03/boris-johnson-vows-to-r...)
 Piers Dobson, “How effective has been the Soft Drinks Industry Levy in reducing the consumption of sugary drinks to help combat obesity? Evidence from supermarket sales of cola,” Independent Study Report, Norwich School, September 2019.
 Public Health England, “Sugar reduction: Report on progress between 2015 and 2018,” 20 September 2019 (https://assets.publishing.service.gov.uk/government/uploads/system/uploa...).
 HM Treasury, “HMRC Tax & NIC Receipts: monthly and annual historical record,” 22 May 2019 (https://assets.publishing.service.gov.uk/government/uploads/system/uploa...).
 British Soft Drinks Association, “Soft Drinks Annual Report 2019” (https://www.britishsoftdrinks.com/-Publications-).
 Adam Briggs, “Sin taxes”—the language is wrong, but the evidence is clear,” BMJ 2019; 366:l4616 (https://doi.org/10.1136/bmj.l4616) (Published 11 July 2019).
Competing interests: No competing interests
The Editorial reads: "Whether they decide to pass this additional cost on to consumers remains to be seen." Anyone visiting food and drink outlets in the United Kingdom will find reduced container sizes with proportionally higher prices. These plans were revealed a year ago by The Guardian newspaper. The question should be, what is the aim of the tax - presumably to reduce population obesity. Can it do that?
The consumption of high energy food and drink contributes to individual weight gain and so is important. However, it is not the cause of the population upward trend in obesity in Britain. Per person consumption by total energy has reduced (both fats and sugar consumption have reduced more dramatically) since the 1970s (MAFF National Food Surveys Great Britain) while per person physical activity has also reduced (DETR National Travel Surveys Great Britain). The trends reflect our addiction to fossil fuels which is a much harder target and has more unsettling global consequences. Distractions like this may simply lead to greater numbers of plastic containers at higher cost.
This widely available (but rarely published) evidence should pose public health practitioners and media commentators the question "what is the abnormality which requires correction?" However, it does not, which is baffling. But if we are determined to be distracted, to reduce the consumption of sugary drinks the logical solution would be as follows. Force a mandatory return to glass containers with return deposits which may even encourage some physical activity, would leave a healthy reminder of your own consumption by the back door, and create greater inconvenience (which always slows things down), limit volume (is 2L in glass even practical to carry or make outside champagne?) and negatively impact on the amount of plastic we produce.
 https://www.theguardian.com/society/2018/jan/05/coca-cola-to-sell-smalle... (accessed 12/07/2019)
Competing interests: No competing interests