The sugar tax saw consumption through soft drinks drop 10 per cent, a Cambridge study has found.
The Government brought in the tax on sugary drinks in April 2018, with health campaigners hoping the higher prices would put consumers off buying the most sugary drinks and lead to a decline in obesity.
It meant manufacturers of soft drinks containing more than 5g of sugar per 100ml are made to pay a levy of 18p a litre to the Treasury, or 24p a litre for sugar content over 8g per 100ml.
Many manufacturers changed their formulas to cut sugar, although classic Coca-cola and Pepsi remained unchanged and instead upped their price.
The amount of sugar in soft drinks dropped by 29 per cent in the UK between 2015 and 2018, according to previous research by Oxford University research, published in BMC Medicine.
Now researchers from Cambridge University have compared weekly purchasing data, collected by market research company Kantar Worldpanel, 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 dataset included approximately 31 million purchases of drinks, confectionery and toiletries from March 2014 to March 2019.
The results showed that the volume of soft drinks bought remained the same but the amount of sugar in those drinks fell by 29.5g, or 10 per cent, 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 per cent 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.”
The team found sales of high-tier sugary drinks, containing more than 8g of sugar per 100ml, had dropped by 155ml (44 per cent) per household per week by March 2019, with 18g less sugar (a 46 per cent decrease).
For low-tier sugary drinks, containing between 5g and 8g of sugar per 100ml, volumes dropped by 177ml (86 per cent) per household per week, with the amount of sugar falling by 12.5g (an 86 per cent 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 per cent 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.
Professor Martin White, also from Cedar, said the results were a “win-win” for public health and the food and drinks industry, as consumers continue to buy the same amount of drinks while “potentially improving people’s health”.
“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,” he added.