The objective of this trial was to test two promising front-of-pack nutrition labels, 1) the United Kingdom’s Multiple Traffic Lights (MTL) label and 2) France’s Nutri-Score (NS), relative to a no-label control. We hypothesized that both labels would improve diet quality but NS would be more effective due to its greater simplicity. We tested this hypothesis via an online grocery store using a 3 × 3 crossover (within-person) design with 154 participants. Outcomes assessed via within person regression models include a modified Alternative Healthy Eating Index (AHEI)-2010 (primary), average Nutri-Score, calories purchased, and singular measures of diet quality of purchase orders. Results show that both labels significantly improve modified AHEI scores relative to Control but neither is statistically superior using this measure. NS performed statistically better than MTL and Control based on average Nutri-Score, yet, unlike MTL it did not statistically reduce calories or sugar from beverages. This suggest that NS may be preferred if the goal is to improve overall diet quality but, because calories are clearly displayed on the label, MTL may perform better if the goal is to reduce total energy intake.
BackgroundFront-of-pack (FOP) nutrition warning labels to identify potentially harmful foods/beverages have recently been considered in Singapore. The objective of this study was to pilot test two promising FOP warning labels intended to reduce purchases of products high in sugar to determine whether a full scale trial testing one or both these labels using actual purchases is warranted.MethodsFive hundred twelve participants ≥21 years old and residing in Singapore completed all study elements online via the NUSMart Online Grocery Store study website. The study was designed as a Randomized Controlled Trial (RCT) where consumers were randomized and asked to hypothetically shop in one of three versions of an online grocery store; 1) no FOP label (control), 2) a graphical high-in-sugar label shaped like a stop sign, or 3) a text-based warning label. The proportion of labelled products purchased (primary outcome) and all secondary measures of diet quality were calculated using participants’ orders. Ordinary Least Squares (OLS) regression was used to compare purchasing behavior across the three study arms.ResultsThe proportion of high-in-sugar products selected (i.e., those targeted for labelling) was largest in the no label control arm at 20%. The proportion was a non-statistically significant 2 percentage points lower (P = 0.146) for the high-in-sugar stop-sign label arm and 4 percentage points lower (P < 0.05) in the warning label with deterrent text arm. We could not reject the hypothesis of equal effectiveness of the two warning labels (P = 0.231).ConclusionsResults suggest that the two health warning labels have potential to reduce demand for high-in-sugar products in Singapore. Future studies should test the influence of these labels using actual purchases in efforts to identify whether either labelling strategy should be considered for adoption in the local setting.Trial registrationThe American Economic Association’s registry for randomized controlled trials; AEARCTR-0003800. Registered 18 January 2019.Electronic supplementary materialThe online version of this article (10.1186/s12889-019-6496-8) contains supplementary material, which is available to authorized users.
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