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Sugar tax ~ the picture widens

In recent times, three significant publications have emerged which should be taken on board by those involved in the debate on sugar tax.

The first is the very recent (June 2018) report of the World Health Organisation (WHO) High Level
Commission on Non-Communicable Diseases, entitled “Time to deliver”[1]. The report highlights the global burden on chronic diseases caused by tobacco, alcohol and poor nutrition. The report has powerful messages to Governments on the directions to take in combatting chronic disease and it points out that investment pays off: “WHO’s global business case for NCDs showed that low- and lower-middle-income countries put in place the most cost-effective interventions for NCDs, by 2030, they will see a return of $ 7 per person for every one dollar invested”. In Ireland, where the obesity bill alone is €1.2bn, we might eat into that figure with an investment of about €180m. At present, we spend almost a tiny fraction of that budget on health promotion against the issues of alcohol, tobacco and nutrition. The former two actually generate a significant income for the state through taxation and the Commission’s report very strongly supports such taxation. However, when it comes to sugar tax, the Commission is somewhat coy: The Commissioners represented rich and diverse views and perspectives. There was broad agreement in most areas, but some views were conflicting and could not be resolved. As such, some recommendations, such as reducing sugar consumption through effective taxation on sugar-sweetened beverages and the accountability of the private sector, could not be reflected in this report, despite broad support from many Commissioners. This conservative language contrasts with the hype of the advocates of the so-called sugar tax, effectively, a tax on sugar sweetened soda. Food for thought indeed. And of course the finger is now pointed at the US with suggestions that it was Eris Hargan, US Deputy Secretary of Health who was the blocking commissioner[2]. Whether Hargan did a solo run and is playing to the gallery is anybody’s guess.

The second study is a scientific paper from a group of British academics who explored whether taxation of sources of sugar other than sugary sodas[3]. Many of us have argued, that the global fashion of taxation of sugars via a tax on sugary sodas, fails to address the real issue of taxing sugars. These authors looked at a broader approach to sugar taxation: “Policies that lead to increases in the price of chocolate and confectionery, cakes and biscuits may lead to additional and greater health gains than similar increases in the price of (sugar sweetened beverages) SSBs through direct reductions in the purchases of these foods and possible positive multiplier effects that reduce demand for other products. Although some uncertainty remains, the associations found in this analysis are sufficiently robust to suggest that policies, and research, concerning the use of fiscal measures should consider a broader range of products than is currently the case”.Now at least we would be forced to take a detailed look at all sources of sugar and how that varies across age groups. These are our own research data for the Irish population[4].

% contribution to Added Sugars
Main food groups involved
Table sugar & jams
Cakes, buns & pastries
Carbonated beverages
Squashes & cordials
Chocolate confectionery
Non-chocolate confectionery

The complexity grows and in the third of the recent papers, the complexity of sugar taxes are elegantly illustrated. Quite how the public would respond to a tax on cakes, confectionery etc as opposed to a soda tax is as yet unknown but somehow I get the feeling that it would be way less popular. 

And now to the final report and by far the most significant. Three years ago, The New Zealand Ministry of Health commissioned a report on the benefits or otherwise of the globally popular sugar tax. It concluded that “there isn’t yet robust evaluative evidence on whether they are effective, or on the size and persistence of any impacts”. In late 2017, the same ministry returned to this issue and commissioned the New Zealand Institute of Economic Research (NZIER) to review new evidence and with a focus on the taxation of sugar sweetened beverages (SSBs).

Overall, the report examined 47 published scientific reports or published studies of the theoretical or actual impact of sugar taxation on the purchase of these products. Each study is considered in full and overall conclusions are drawn. The report breaks down the complexity of the sugar tax issue into 5 elements which underlie the logic of such taxes. It assumes
(1) that imposing a “sugar tax” will increase the price of the taxed item, SSB’s;
(2) the increase in price will to lead to a reduction in consumption of such beverages; (3) reduced SSB consumption will lead to a reduction in calorie intake;
(4) lower caloric intakes will lead to lower adverse health risk factors such as improved diabetes or hypertension management and
(5) in turn, that will lead to better health outcomes.

These 5 steps were considered in turn, taking all available evidence into account.

Imposing a “sugar tax” will increase the price of sugar sweetened beverages
There are two main possibilities here. The manufacturers of SSBs could absorb the tax and make a loss. In the real world, those who sell SSB’s also sell diet sweetened beverages and also juices and waters of various hues. So, it is not beyond the bounds of possibility that the SSB manufacturer absorbs most of the cost of the SSB tax thus protecting the consumer from a full price hike on fizzy drinks while protecting their profits through marginally higher prices on a range of SSB alternatives that they sell into the market (juices, waters, diet drinks) .
Increased price of sugar sweetened beverages will lead to a lower intake
Without wishing to delve too deeply into the econometric arguments of the report, there is one critically important point made by the authors. The models put forward in the sugar tax debate are focused on the sensitivity of the overall market to changes in the price of SSBs. However, the report points out that there is no data on how the response shapes out at sub-group levels of the market. Will high SSB consumers be more or less price sensitive than low SSB consumers? Will prevailing body weight play a role in shaping price sensitivity? Will these two factors interact such that overweight high consumers behave differently than normal weight high consumers?

A lower sugar intake will lead to a lower calorie intake.
The report points out that if the price of SSBs leads to a lower intake of these products, it doesn’t necessarily follow that other untaxed products might not fill the void. Indeed, human intervention studies, which have surreptitiously  lowered the sugar levels of foods have found that energy intake remains more or less constant with other foods filling the caloric gap. The biological data would suggest that the caloric deficit made by reduced SSB consumption would be largely, but not completely, compensated through higher intakes of many other foods. Thus whatever the drop in calories will be, it will be only a fraction of the present contribution of SSBs to calorie intake among SSB consumers. All of this debate means nothing to the majority of the population that don’t consume SSBs, across all age groups. We must accept that among SSB consumers, such a tax will cause a drop in caloric intake but at just a fraction of the present contribution of SSBs to calorie intake

If calorie intakes are lowered, will body weight fall? If bodyweight falls, will health outcomes inevitably follow.
The simple answer to both is yes. A small deficit of calories over a long period of time would indeed create weight loss. One also has to assume that weight loss will have some health benefits but one can also predict that small changes and large changes in body weight, will have respectively smaller and larger effects on health such as Type 2 diabetes or high blood pressure.

The NZIER report itself, having considered all 47 studies on the effectiveness of a tax on SSBs and examining each for the five elements of the logic chain it set out  from tax imposition to measurable health benefits, concludes “As we noted in the section on frameworks, there are multiple steps in the chain of intervention logic from the well-established principle that an increase in the price of a good leads to a reduction in consumption of that good and, all else equal, to an improvement in health outcomes…. Our conclusion is that the evidence base gets weaker further along the chain of intervention logic… We have yet to see any clear evidence that imposing a
sugar tax would meet a comprehensive cost-benefit test”

All in all, the science and politics of sugar tax rolls on. Of the three reports, that of the New Zealand Economics Institute is the one which we need to focus most on. In particular, we need to focus on each of the links in the chain it outlines for the sugar tax-obesity link and apply them methodically to the monitoring of the soda tax and its effects on health

[3] Richard D Smith, Laura Cornelsen, Diana Quirmbach, Susan A Jebb, Theresa M Marteau Are sweet snacks more sensitive to price increases than sugar-sweetened beverages: analysis of British food purchase data. BMJ Open 2018;8:e019788. doi:10.1136/bmjopen-2017-019788

[4] Triona Joyce, Sinead N. McCarthy and Michael J. Gibney. British Journal of Nutrition (2008), 99, 1117–1126 Relationship between energy from added sugars and frequency of added sugars intake in Irish children, teenagers and adults


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