The study was conducted by University of Otago researchers and modelled the effects of a hypothesised 20% fruit and vegetable subsidy as well as taxes on saturated fat, salt, sugar and junk food (defined as non-essential, energy dense foods) on a New Zealand population over 30 years based on New Zealand National Nutrition Survey data.
The sugar taxation was modelled based on tax for all foods and beverages with sugar, not sugar-sweetened beverages alone.
Two of the main outcomes investigated were: The effects of these on public health disease incidences for 17 diet-related diseases (coronary heart disease, stroke, osteoarthritis, diabetes, and 13 types of cancers), and the potential public health gains (calculated based on the number of Health-Adjusted Life Years (HALYs) gained).
Sugar taxes emerged as the most powerful intervention in terms of reducing the incidences of these diseases when compared to salt, saturated fat, or junk food taxes, or the 20% fruit and vegetable subsidy.
“The implementation of a sugar tax led to higher outcomes than any of the other taxes and subsidies investigated when it came to reducing incidences of diet-related diseases such as diabetes (-32.7% in men, -26.7% in women), stroke (-18.2% in men, -14.7% in women), coronary heart disease (-15.8% in men, -13.6% in women), colorectal cancer (-5.9% in men, -1.5% in women) and osteoarthritis (16.3% in men, 12.8% in women),” said the study authors.
This was particularly obvious for diabetes, where it beat out the closest contender saturated fat tax (-20.1% for men, -16.4% for women) by over 10% on average; as well as osteoarthritis where it beat salt tax (-10.2% for men, -7.7% for women) by over 5%.
“All the interventions we modelled led to notable reductions in most chronic disease rates – the largest being [the 32.7% reduction for diabetes in men by a sugar tax],” said lead author Professor Tony Blakely.
Sugar tax was also the top contributor to HALYs gained, hence overall public health gains, based on the modelling.
“[Sugar tax would] add a total of 581 HALYs per 1,000 New Zealand consumers, [higher than] 375 HALYs from the salt tax, 361 HALYs from the saturated fat tax, 212 HALYs from the fruit and vegetable subsidy or 127 HALYs from the junk food tax,” Prof Blakely added.
The New Zealand Dental Association (NZDA) lauded the study’s findings, highlighting that the implementation of a sugar tax would also very likely show benefits to improving population oral health.
“A tax on sugar shows the greatest overall health benefits in this study, and if implemented, we think oral health could be one of the biggest improvements,” said NZDA sugary drinks spokesperson Dr Rob Beaglehole in a formal statement.
“[Sugar] consumption must drop if overall oral health is to improve in New Zealand.”
Overall though, the researchers voiced support for a ‘combination scheme’ as opposed to implementing a single tax as the effects could potentially be even more maximised.
“There are large potential health gains from such a scheme, [as we saw public health benefits] from the other measures too. For example, the fruit and vegetable subsidy saw a significant disease incidence reduction for stroke (-16·3% for men, -11·3% for women),” said Prof Blakely.
As for the junk food tax, which was found to add the least HALYs, the study still urged for this to be implemented in tandem as it had demonstrated effects in reducing the purchases of such unhealthy foods.
“Mexico’s introduction of its 8% tax on junk food in 2014 reduced purchasing of these foods by 6%, [demonstrating that] these measures are both feasible and effective,” said study co-author Dr Cristina Cleghorn.
The study also looked into the effects of combining the individual nutrient taxes with the fruit and vegetable subsidy, and found all of these combinations to have more powerful effects than the individual taxes.
Calculating public health gains here as added HALYs for the overall population of study, the base for comparison was estimated at 173 million HALYs for the population if no interventions whatsoever were implemented.
“With just sugar tax implemented, this increased by 1.48% to 2.56 million HALYs, but with both sugar tax and a 20% fruit and vegetable subsidy, this increased by 1.91% to 3.31 million – a total gain of 0.43% or 0.75 million HALYs in total,” stated the study.
Similar results were seen for the salt tax-fruit and vegetable subsidy and saturated fat tax-fruit and vegetable subsidy combinations, as both increased HALYs by 0.46% (0.8 million).
Easier said than done
That said, implementing any such schemes, combination or otherwise would still need to go through multiple hurdles, as the New Zealand government has said time and again that food taxes, and especially sugar taxes, are not on the table.
The food and beverage industry is very clearly against any such tax being implemented, with health groups such as NZDA on the other end.
Prof Blakely agrees that there are ‘multiple other considerations’ when making decisions on food taxes and subsidies, but stressed that these findings show a clear benefit to these.
“[The government obviously also has] multiple other considerations such as political and social acceptability, food industry perspectives, deadweight costs, etc. [but] the health gains from food taxes and subsidies require serious policy consideration and public discussion,” he said.
The researchers added that these decisions ‘should not be made based only on simulation modelling studies’, but also emphasise the wider benefits to be begotten.
“[Taxes] could also prompt food industry product reformulation to avoid tax, further enhancing health gains over and above the direct effects that we modelled,” they said.
Study: The effect of food taxes and subsidies on population health and health costs: a modelling study
Source: The Lancet
Authors: Blakely, T. et.al.