Evaluating Food Policy Interventions Using NUSMart

Using a 3-arm randomized controlled trial, the investigators aim to rigorously evaluate the effects of two front-of-pack (FOP) food labels on diet quality. The first food label is a modified version of Chilean warning FOP label and the second food label is a modified version of French FOP label, Nutri-Score. The investigators used an experimental online grocery store, called NUSMart, which is similar in design to commercial web-based grocery stores to test these two FOP labels. Participants were randomly assigned to one of the following arms and asked to complete a one-time hypothetical shop.

Arm 1: Participants experienced a default version of NUSMart which replicated the traditional shopping experience of online grocery stores with no FOP labels (Control).

Arm 2: Same as Arm 1 NUSMart except that Chilean warning FOP labels were displayed on less healthy food and beverages. Products with specific nutrients (i.e. sugar, sodium, saturated fat, energy) falling outside the bounds of the thresholds defined by the Chilean warning labels were depicted with the warning labels on them.

Arm 3: Same as Arm 1 NUSMart except that Nutri-Score FOP labels along with % sugar per serving were displayed on all food and beverages. These labels score products on the basis of 7 nutrients (calories, saturated fats, sugar, salt, fibre, protein and percentage of fruits, vegetables and nuts) from A to E (best to worst). To ensure that participants understood what Nutri-Score labels mean and how they work, an introductory video was shown before shopping.

The investigators hypothesize the following:

Hypothesis 1: Diet quality, as measured by weighted average Nutri-Score point of shoppers' final baskets, will be greatest in Arm 3, followed by Arm 2, followed by Control.

Hypothesis 2: Grams of sugar per serving/ milligrams of sodium per serving/ grams of saturated fat per serving/ calories per serving will be least in Arm 2, followed by Arm 3, followed by Control.