Households bought 10% less sugar through soft drinks in the year after the sugar tax was introduced in the UK, research suggests.
The tax came into force in April 2018, with manufacturers of soft drinks containing more than 5g of sugar per 100ml made to pay a levy of 18p a litre to the Treasury, or 24p a litre for sugar content over 8g per 100ml.
The Government and health campaigners hoped the higher prices would put consumers off buying the most sugary drinks and lead to a decline in obesity.
Many manufacturers changed their formulas to cut sugar.
Researchers from Cambridge University compared weekly purchasing data in March 2019 with an estimate, based on pre-existing trends, of how purchases would have looked that month without the sugar tax in place.
The volume of soft drinks bought remained the same but the amount of sugar in those drinks fell by 29.5g, or 10%, per household per week compared with the estimate, according to the study.
Dr David Pell, from Cambridge’s Centre for Diet and Activity Research (Cedar), said: “A 10% drop in the amount of sugar purchased from soft drinks might sound modest, but we know there’s an association between the amount of sugar drinks we consume and the risk of developing conditions such as obesity, type 2 diabetes and high blood pressure.
“Cutting out even a relatively small amount of sugar should have important impacts on the number of people with obesity and diabetes.”
Professor Martin White, also from Cedar, said: “The Soft Drinks Industry Levy appears to have led to a reduction in the amount of sugar that people are purchasing in soft drinks without impacting on the overall volume of soft drinks sold.
“It’s likely that this is due to manufacturers reformulating their products and reducing the sugar concentration in their drinks, as well as to consumers switching to lower sugar alternatives.
“This represents a valuable win-win for public health and the food industry – potentially improving people’s health with no detrimental effect on the volume of soft drinks that companies are selling.”
The researchers analysed data collected by market research company Kantar Worldpanel, which asked participating households to record their weekly food and drink purchases.
The dataset included approximately 31 million purchases of drinks, confectionery and toiletries from March 2014 to March 2019.
The team found sales of high-tier sugary drinks, containing more than 8g of sugar per 100ml, had dropped by 155ml (44%) per household per week by March 2019, with 18g less sugar (a 46% decrease).
For low-tier sugary drinks, containing between 5g and 8g of sugar per 100ml, volumes dropped by 177ml (86%) per household per week, with the amount of sugar falling by 12.5g (an 86% decrease).
Although there was no change in the volume of drinks sold with less than 5g of sugar per 100ml, which have no levy, some increased in their sugar content.
The sugar purchased from these drinks increased by 15.3g per household per week, equivalent to a 166% increase.
The study also looked at drinks which are exempt from the levy – with milk and milk-based drinks falling by 11.9g of sugar per week, no-added-sugar fruit juices falling by 0.8g per week and drinks sold as powders falling by 1.6g per week.
When all soft drinks were combined, the volume of drinks purchased did not change, but sugar decreased by 29.5g, according to the research.