Published in the Journal of Epidemiology and Community Health, the study found that increasing the price of high sugar drinks led to an increase in purchases of lager.
The results, however, were mixed, with variations seen between types of beverage, the sugar content of drinks taxed, and consumer demographics.
However, researchers say their work highlights that any research into the effectiveness of a sugar tax must go beyond a simple analysis of sugary drink sales and consider wider beverage purchases.
Little research on how sugar tax will affect alcohol sales
With the introduction of sugar taxes (generally on non-alcoholic added sugar beverages) gathering pace around the globe, researchers in the UK (where a tax is due to be introduced in April) highlight that little is known about the effect on alcohol sales.
Beer and wine provide on average 43 and 85 kcals per 100ml respectively, compared to 40 kcal in 100ml of cola. Currently, adults in the UK consume 106 kcals each a day from alcoholic drinks, a little more than from sugar-sweetened beverages (98kcal).
The researchers took data from 31,919 households in Great Britain, together accounting for around 6 million drinks purchases, as well as social and demographic data for each household.
Some of the key findings from the study were:
- A rise in the price of high sugar content drinks (more than 8g sugar per 100ml) led to more purchases of diet drinks, juices and lager. However, medium sugar content drinks and spirits fell.
- A price rise in medium sugar drinks (between 5 and 8g/100ml) led to falls in beer, lager and wine purchases.
- Price rises in diet or low sugar drinks (less than 5g/100ml) were associated with increased purchases of all other drink types, except high and low sugar content beverages.
- In high income households, price increases in high sugar content drinks were associated with a fall in sales of cider, while in the middle income group, these price increases were associated with a fall in the purchase of spirits, but an increase in those of lager. No declines in alcohol purchases were evident in low income households.
- A price hike for medium sugar content drinks would ‘seem to be most effective’, while applying one to diet/low sugar drinks would ‘seem to be the least effective’, suggesting that the threshold of sugar content for any price rise could be crucial, say researchers.
Alcohol could appear more affordable
The increase in the cost of sugar-sweetened beverages could make the cost of alcohol appear more affordable, because of a narrowed gap in price.
However, the researchers note that, although their study highlights ‘significant relationships’ between beverages purchased, it cannot explain them.
“Why, for example, would an increase in price of high-sugar drinks appear to cause some mid-income households to reduce expenditure on them, but also increase their purchase of lager?
“It may be that it narrows the relative price difference to make lager appear more ‘affordable’, through changing the households’ cost-benefit calculations of SSB versus lager, but this sort of behavioral explanation requires further, primary, research.
“It may be easier to explain some of the complementary relationships – that for instance purchase of beer or wine falls as the price of SSB increases as there is less money available overall, or because for some drinks they are mixed, but again we cannot really understand the possible explanations without further primary research.
“Nonetheless, the presence of this range of significant substitute and complementary relationships between SSB and other alcoholic and non-alcoholic beverages suggests an urgent need for follow-up work based on with primary research to understand the reasons for the relationships.”
One key takeaway for the researchers is that any sugar tax policy that increases the price of diet or low-sugar drinks could lead to increases in alcoholic drink purchases.
“This is important for proposed industry levies, such as that proposed for the UK, as industry is free to determine how to recoup the levy from consumers with an option to increase the price of all drinks, including diet drinks.
“If so, this could reduce the beneficial effects from a rise in the price of medium-sugar drinks and add negative effects from diet drink price increases through the increased purchase of alcohol.”
A number of sugar taxes proposed to date do focus on medium and high sugar drinks: the UK’s sugar tax, for example, will only kick in for drinks with 5g sugar per 100ml or more; while Seattle dropped diet drinks from its tax.
Sugar tax research must go beyond sugary drinks
The researchers conclude that any research on the effectiveness of sugar taxes needs to go beyond a simple analysis of sugary-drink sales and take wider beverage consumption trends into account.
“Although not definitive, the relationships found in this analysis are sufficiently robust to suggest that policies – and research – concerning the price of SSBs need to consider the effects beyond the SSBs targeted and support the need for further primary research on the behavior patterns associated with alcoholic and non-alcoholic beverage choices.”
Source: Quirmbach D, Cornelsen L, Jebb SA, et al: 'Effect of increasing the price of sugar-sweetened beverages on alcoholic beverage purchases: an economic analysis of sales data'. J Epidemiol Community Health: Published Online First: 23 January 2018. doi: 10.1136/jech-2017-209791