Sugar tax “may have prevented 5,000 cases of obesity in young girls,” flags new research

27 Jan 2023 --- The introduction of the soft drinks industry levy (SDIL) in the UK has been followed by a decrease in the number of cases of obesity among older primary school children, notably girls, according to Cambridge researchers.

Estimates suggest that the sugar tax may have prevented around 5,000 cases of obesity in year six girls (aged 10 to 11 years) alone.

The study, published in PLOS Medicine, looked at the levy’s impact on reception-age children and those in year six but found no significant association between the levy and obesity levels in year six boys or younger children from reception class.

The National Institute of Health and Care Research (NIHR) and the Medical Research Council supported the research. The study was also a collaboration involving researchers from the University of Cambridge, the London School of Hygiene and Tropical Medicine, the University of Oxford, the Great Ormond Street Institute of Child Health and the University of Bath.

A global issue
Obesity has become a global public health problem.

In England, one in ten reception-age children (four to five years old) is living with obesity and this figure doubles to one in five children in year six. 

Children who are obese are more likely to suffer from serious health problems, including high blood pressure, Type 2 diabetes and depression in childhood and later life.

In the UK, young people consume significantly more added sugars than is recommended – by late adolescence, they typically consume 70 g of added sugar per day, more than double the recommended amount (30 g). 

A significant source of this is sugar-sweetened drinks. Children from deprived households are more likely to be at risk of obesity and to be heavy consumers of sugar-sweetened beverages (SSBs).

Tackling excessive consumption 
In April 2018, to protect children from excessive sugar consumption and tackle childhood obesity, the UK government introduced a two-tier sugar tax on SSBs.

Researchers from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge tracked changes in the levels of obesity in children in England in reception year and year six between 2014 and 2020.

Taking account of previous trends in obesity levels, they compared changes in levels of obesity 19 months after the sugar tax came into effect.

The team found that the introduction of the sugar tax was associated with an 8% relative reduction in obesity levels in year six girls, equivalent to preventing 5,234 cases of obesity per year in this group alone. 

Reductions were most significant in girls whose schools were in deprived areas, where children are known to consume the most considerable amount of sugary drinks – those living in the most deprived areas saw a 9% reduction.

“No associations” in reception-aged children  
However, the team found no associations between the sugar tax coming into effect and changes in obesity levels in children from reception classes. In year six boys, there was no overall change in obesity prevalence.

“We urgently need to find ways to tackle the increasing numbers of children living with obesity. Otherwise, we risk our children growing up to face significant health problems,” says Dr. Nina Rogers from the MRC Epidemiology Unit at Cambridge, the study’s first author. 

“That was one reason the UK’s soft drinks industry levy was introduced, and the evidence is promising. We’ve shown for the first time that it is likely to have helped prevent thousands of children each year from becoming obese.”

“It isn’t a clear picture, though, as it was mainly older girls who benefited. But the fact that we saw the biggest difference among girls from areas of high deprivation is important and is a step toward reducing the health inequalities they face,” she explains. In the UK, young people consume significantly more added sugars than are recommended.

Although the researchers found an association rather than a causal link, this study adds to previous findings that the levy was associated with a substantial reduction of sugar in soft drinks.

“Children from more deprived backgrounds tend to consume the largest amount of sugary drinks, and it was among girls in this group that we saw the biggest change,” adds senior author Professor Jean Adams from the MRC Epidemiology Unit.

Younger, older; girl, boy? 
There are several reasons why the sugar tax did not lead to changes in levels of obesity among younger children, they say. Very young children consume fewer sugar-sweetened drinks than older children, so the soft drinks levy would have had a more negligible effect. 

Similarly, fruit juices are not included in the levy but contribute similar amounts of sugar in young children’s diets as sugar-sweetened beverages.

It’s unclear why the sugar tax might affect obesity prevalence in girls and boys differently, but the researchers state that boys are higher consumers of sugar-sweetened beverages. 

One explanation the researchers put forward is the possible impact of advertising – numerous studies have found that boys are often exposed to more food advertising content than girls through higher levels of TV viewing and in how adverts are framed. 

Notably, compared to girls, physical activity is often used to promote junk food and boys are more likely to believe that energy-dense junk foods depicted in adverts will boost physical performance and are therefore more likely to choose energy-dense, nutrient-poor products following endorsements from celebrities, for example. 

Edited by Elizabeth Green