The scientists estimated the impact on rates of obesity, type 2 diabetes and tooth decay according to best and worst-case scenarios of three potential industry responses: reducing the sugar content of soft drinks, raising the price of sugary drinks and increasing the range of low-sugar drinks.
Using a comparative risk assessment model with the 2014 UK population as a baseline, they say the best health benefits are to be derived from product reformulation.
This would result in 144,383 fewer cases of obesity among the 15 million obese adults and children in the UK, as well as 19,094 fewer incident cases of type 2 diabetes and 269,375 fewer decayed, missing or filled in teeth annually.
In comparison, a 20% price hike on high and mid-sugar drinks would lead to an estimated reduction in obesity of 81,600 as well as 10,800 fewer cases of diabetes and 149,000 fewer decaying teeth per year.
Dr Adam Briggs from the University of Oxford and lead author of the study said all of the industry responses have the potential to improve health by reducing the rates of obesity diabetes and tooth decay.
“The extent of the health benefits of the tax will depend on industry's response,” he added. “We must therefore be vigilant to ensure the food industry acts to remove sugar from soft drinks, and that where the tax is passed on to consumers it increases the price of targeted products only - drinks with high levels of sugar."
The study authors estimate that the biggest impact will be felt by children.
Although a tax on sugar-sweetened beverages has been applied in other countries, the UK would be the first to introduce a tiered industry levy, with a high tax for drinks with more than 8 g of sugar per 100 ml, a moderate tax for 5–8 g and no tax for drinks with less than 5 g, rather than a sales tax, write the authors.
This means that product reformulation could be an attractive option for firms wishing to avoid the levy, although the government has not set any mandatory requirements for industry responses meaning companies could choose to pass on the extra costs to consumers if they wish.
Co-author Professor Susan Jebb, also from the University of Oxford, said: "In spite of the uncertainties, the direction of the effect is clear; this levy will have a positive impact, especially on children's health. Of course, on its own a soft drinks levy cannot solve the obesity crisis, but we should not underestimate the importance of this step, both for the UK and as a case study for other parts of the world.”
The researchers estimate that the first impact of the tax would be seen on instances of tooth decay, followed by obesity levels and then rates of type 2 diabetes.
“The greatest benefit for obesity and oral health would be among individuals aged younger than 18 years, with people aged older than 65 years having the largest absolute decreases in diabetes incidence,” they write.
However they add: "Uncertainty exists as to how industry will react and about estimation of health outcomes. Health gains could be maximised by substantial product reformulation, with additional benefits possible if the levy is passed on to purchasers through raising of the price of high-sugar and mid-sugar drinks and activities to increase the market share of low-sugar products.”
According to the Office for Budget Responsibility, if manufacturers pass on the full cost to consumers the price of a soft drink could rise by 18 to 24 p.
The worst-case scenario assumed that major soft drink manufacturers would apply the cost of the tax across their entire portfolio including both diet beverages and bottled water, resulting in a 6% price rise.
For our round-up of sugar tax policies around the world – one of 2016's defining trends to impact the global food and beverage industry – click here.
Source: The Lancet Journal
“Health impact assessment of the UK soft drinks industry levy: a comparative risk assessment modelling study”
First published online 15 December 2016, DOI: http://dx.doi.org/10.1016/S2468-2667(16)30037-8
Authors: Adam D M Briggs, Oliver T Mytton, Ariane Kehlbacher, Richard Tiffin et al.