The Effect of Price Changes and Teaspoon Labelling on Intention to Purchase Sugar-Sweetened Beverages: A Discrete Choice Experiment.

introductionChildhood obesity is a major public health concern and sugar-sweetened beverages (SSBs) are a known contributor. SSB taxation and food labelling have been proposed as policies to reduce consumption by changing purchasing behaviours. The study aimed to analyse caregivers' preferences on commonly purchased SSBs in Australia and to determine the effect of price increases and teaspoon labelling on their purchasing intentions.

methodsWe used a discrete choice experiment (DCE) to obtain data about choices between SSB and non-SSB alternatives. 563 caregivers, who had young children aged 3-7 years, completed the experiment online. 286 were randomly allocated to receive choice sets with plain labelling while 277 were assigned to teaspoon labelling. Each participant completed nine choice scenarios where they chose between six SSB and non-SSB beverage options or a no-beverage option, with beverage prices varying between scenarios. While hypothetical, price and teaspoon labelling for sugar content for each beverage was obtained from an informal market survey. Responses from the DCE were modelled using random parameters logit within a random utility theory framework. Household income and children's consumption volumes of soft drink were used to explore preference heterogeneity.

resultsUsing mixed logit as the final model, we found that higher reduction in intended purchases was observed for soft drink and fruit drink in teaspoon labelling than it was in plain labelling. Participants exposed to teaspoon labelling intended to purchase less of flavoured milk and fruit juice compared to those exposed to plain labelling. Compared to baseline prices, a hypothetical 20% increase in SSB prices and the presentation of 'teaspoons of sugar' labelling were predicted to reduce intentional SSB purchases and increase intentional non-SSB purchases. Within each labelling group, there were no significant differences of intentional purchases between the highest and the lowest income quintile, high and low consumers of soft drinks. However, compared to plain labelling, teaspoon labelling was predicted to strongly influence intentional purchases of SSBs and non-SSBs.

conclusionThis study suggests that a policy to increase SSB price and include teaspoon labelling would lead to a reduced consumption of SSBs and increased consumption of non-SSBs.