The case for a sugar tax is sweetened if NZIER report is overlooked

When Prime Minister Jacinda Ardern said New Zealand would  not join the countries that are signing up for a war against drugs – as championed by US President Donald Trump – she said her government has an agenda that is focused on addressing issues around drug use.

“We have a number of challenges that are quite specific to New Zealand and the type of drugs that are present, but also I’m taking a health approach.

“We want to do what works, so we are using a strong evidence-base to do that.”

Whether she will similarly use a strong evidence base to decide on how to reduce sugar consumption is a moot point.

Questioned a year ago by Mike Hosking on Newstalk ZB, she said reducing sugar is a priority of the new government.

Asked by Hosking if she backed a sugar tax, she said she is in support of limiting sugar in New Zealand foods.

“We’ve backed reducing sugar in our foods, in fact most Kiwis I think would support that,” she said.

“I know we’ve got a problem, and I think people would be surprised by how much sugar is being placed in everyday items.”

Ardern said a broader approach was needed to be fully effective.

“One of the issues we’ve had though, is people have always promoted the idea of a tax on sugary drinks as being the answer, but actually the increasing use of sugar is across a number of food items, not just drinks.”

Ardern said the government would not rule out a sugar tax but other options would be considered.

Eleven months later, the New Zealand Herald published the advice provided to Ardern in February in a briefing from the Ministry of Health’s chief science advisor, Dr John Potter.

Potter is a professor at the Centre for Public Health Research at Massey University.

Each of 19 bullet points in the document unequivocally helped make the case for a tax on sugar sweetened beverages.

In the document, released under the Official Information Act, Potter said:

“The Finnish tax on confectionery, ice cream and SSBs showed a continuing decline in consumption of high-sugar products with the imposition of steadily increasing taxes over consecutive years.

“Most crucially, the recent Berkeley, USA study showed clearly that a tax of one per cent per 30gm decreased consumption of SSBs in low-income communities and increased consumption of water.”

Potter’s advice is that a tax of 20 per cent has been shown to work, but it should be based on volume or sugar content, not value.

“Reduction of consumption via a tax will probably be greatest among the households with the lowest disposable income. In New Zealand, Māori and Pacific will benefit strongly.”

Suspiciously supportive figures were injected into the paper.

Over time a tax could save 50 lives a year and save at least $6 million in health costs.   It would raise about $40m in revenue.

Potter advised a sugar tax could be an evidence-based “anchor” in a comprehensive strategy, including restrictions on marketing to children, education and safer biking routes.

Before the Herald flushed this advice into the public domain, Health Minister Clark had hired a fellow described as one of New Zealand’s most vocal advocates for a sugar tax as an advisor in his office.

According to this Herald report:

His appointment comes as pressure grows on the Government to slap a tax on sugary products, with two DHBs calling for sugary drinks to be made more expensive.

Beaglehole – dubbed the “anti-sugar man” in one media profile – has been a long-standing advocate of such a measure and was the dental officer of health for Nelson-Marlborough DHB.

Eric Crampton, chief economist with The New Zealand Initiative in Wellington, has been monitoring the sugar-tax champions and their arguments.

Last week he described Potter’s bullet points as “some rather shoddy advice” on the effects of sugar taxes.

None of the two pages of unreferenced bullet points mentioned the comprehensive literature review commissioned by the ministry, undertaken by the NZIER, and released by the ministry just a few days before Potter provided his list of bullet points.

Crampton accordingly asked asked the ministry for more information about the process around the chief science advisor’s advice to the Prime Minister:

  1. Did any request from Sir Peter Gluckman’s office for that advice run through the Ministry of Health? If it did, please provide any documentation around it.
  2. Did Chief Science Advisor John Potter’s reply to Sir Peter’s office, addressed to the Prime Minister, run through any quality assurance process at the Ministry of Health? If so, please provide any documentation produced as part of that quality assurance process.
  3. At what point did the Ministry of Health become aware that Dr Potter was producing this advice for the Prime Minister? How did it become aware that this advice was being produced?
  4. Please provide any documentation, including but not limited to internal emails, meeting notes, and recollections of relevant officials [particularly the economics team at the Ministry], of any discussions within the Ministry of Health about:
    1. The quality of John Potter’s advice;
    2. That advice’s consistency with prior Ministry advice regarding sugar taxes;
    3. The process by which this advice was requested and produced.
  5. Does the Ministry of Health view it as appropriate that advice was provided to the Prime Minister on sugar taxes by the Ministry of Health’s Chief Science Advisor with no reference whatsoever to the work that the Ministry had received from NZIER in August 2017 and that the Ministry had released under the Official Information Act only 17 days prior to Potter’s note? Is this the kind of thing that the Ministry views as good practice and process? If not, what processes if any has the Ministry undertaken to ensure that advice produced by its Chief Science Advisor goes through any kind of quality assurance process?

The Ministry’s response – Crampton complained – “is absurdly lame”.  It says:

“I can advise that the request for advice was made directly to Professor Potter by the Prime Minister’s Chief Science Advisor. Professor Potter prepared a succinct summary note in response. It was not intended as a stocktake of all available evidence.

“The Ministry of Health became aware of Professor Potter’s note on 20 August 2018 when the Department of the Prime Minister and Cabinet consulted us about its release under the Act. I have identified one email chain in scope of this part of your request. This is enclosed, with some material redacted … to protect the privacy of natural persons.

“At the time, officials recall that Professor Potter’s note drew different conclusions about the benefits of taxing sugar-sweetened beverages from the study undertaken by NZIER. This is not unexpected as taxing sugar-sweetened beverages is a contested area.

“The Ministry welcomes debate on these types of complex health issues, including the interpretation of evidence and best practice.

“The role of the Chief Science Advisor is to provide independent comment and advice on matters related to the health and disability sector. The Ministry supports Professor Potter providing information and advice to a range of stakeholders in keeping with his role as Chief Science Advisor.

Crampton comments:

The first the Ministry knew about Potter’s note was when it was being released under OIA.  MoH noticed that it varied from the advice the Ministry commissioned. But if the Chief Science Advisor chooses to ignore that report and produce a one-sided, distorted view of things for the Prime Minister’s consumption, they seem cool with that.  How completely lame.

Crampton is sure Potter would have seen the NZIER report before producing his bullet points. He has lodged another OIA request to confirm this.

The NZIER report to the Ministry of Health, by the way, is titled Sugar taxes – A review of the evidence.

After reviewing the literature, the authors found:

• Taxes do generally appear to be passed through to prices and some
reduced demand is likely
• Estimates of reduced intake are often overstated due to methodological
flaws and incomplete measurement
• Price elasticities from early studies with fundamental methodological flaws
have later been used in a number of other studies to assess the impact of
sugar taxes, resulting in significantly overestimated reductions in demand
• There is insufficient evidence to judge whether consumers are substituting
other sources of sugar or calories in the face of taxes on sugar in drinks
• Studies using sound methods report reductions in intake that are likely too
small to generate health benefits and could easily be cancelled out by
substitution of other sources of sugar or calories
• No study based on actual experience with sugar taxes has identified an
impact on health outcomes
• Studies that report health improvements are modelling studies that have
assumed a meaningful change in sugar intake with no compensatory
substitution, rather than being based on observations of real behaviour.

The NZIER conclusion was brief and blunt: the evidence that sugar taxes improve health is weak.

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