Singapore’s new four-tiered drinks labelling system, Nutri-Grade, is likely to help consumers cut their sugar intake, a study by Duke-NUS researchers found.

The researchers, led by health economists Dr Soye Shin and Professor Eric Finkelstein from Duke-NUS’ Health Services and Systems Research Programme, conducted a randomised controlled trial using a bespoke built online grocery store to test whether the labelling system, which ranks drinks from A to D depending on their sugar and saturated fat content, influences consumer choice. They tasked 138 participants to shop for a week’s worth of groceries, spending a minimum of S$50, including at least one beverage.

 
“We have our own online grocery store, called NUSMart that rivals other major supermarkets in Singapore, and we use our store to randomise people to different shopping experiences,” explained Shin, the principal investigator and first author of the study. “For this study, half the participants browsed an NUSMart where drinks were labelled with the new Nutri-Grade A to D labels, while the other half didn’t see those labels. And then, we looked at what they put into their shopping baskets.”

Conducted just before the labelling system came into effect in December 2022, the findings, which have been published in the International Journal of Behavioural Nutrition and Physical Activity, showed that trial participants exposed to the labels opted for drinks with 1.5g sugar less per serving—equivalent to about 2.9g of sugar per 330ml canned drink—by avoiding the drinks ranked in the least healthy C and D bands.

“We saw consumers in the Nutri-Grade label arm opt for more A- and B-graded beverages compared with those who didn’t see the labels,” said Finkelstein.

“Compared to what was bought during the shopping experience without the Nutri-Grade labels, those bought with the Nutri-Grade labels had a reduced sugar content of 1.5 grams per serving,” added Shin.

The new labelling system covers packaged drinks including fruit juices, juice and soft drinks, milk and yoghurt drinks as well as instant powdered beverages. It complements the Healthier Choice Symbol, which helps consumers make informed purchasing decisions.

“Singapore now has the highest prevalence of diabetes among developed countries,” said Finkelstein. “Our work was designed to assess whether the Nutri-Grade system might help combat this problem.”

While someone who consumes large quantities of sugary beverages will benefit by opting for less sugary options, the study showed no significant differences in the total calories, saturated fat or other nutrients present in the purchased goods—likely because beverages account for a small part of the total shopping basket.

“This reveals the limits of a labelling system focussing on only pre-packaged beverages,” added Shin. “If you can move away from the beverages that have no nutritional value, beverages that are the C and D beverages, it is a nudge in the right direction. Over the long term this can be part of a larger strategy to address the war on diabetes, rising rates of obesity and cardiovascular disease.”

To extend the impact, the new labelling system will also be applied to freshly prepared beverages by the end of 2023.

“The Duke-NUS study affirms that the Nutri-Grade mark is a good tool in guiding consumers to identify and choose beverages lower in sugar,” said Mr Terence Ng, the director of policy and strategy development at the Health Promotion Board. “With the extension of these measures to freshly prepared beverages by end 2023, we aim to help Singaporeans reduce sugar consumption through beverages over time.”

Professor Eric Finkelstein and Dr Soye Shin investigated how likely the new labelling system is to influence consumers' drinks choices
 

For the Duke-NUS research team, the next step will be to evaluate Nutri-Grade’s effects using real-world consumer data.

“With real-world data, we will examine the net effects of the labels by accounting for responses from consumers as well as manufacturers,” said Shin. 

“We also want to understand whether we see the same behaviour change in those in-the-moment purchases, and that will be our next study because it is much easier to resist temptation when it is in the future. But at least for online shopping for future consumption, no doubt these labels are working.”

Principal investigator Dr Soye Shin