The impact of adding front-of-package sodium content labels to grocery products: an experimental study
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A high sodium diet is a predominant risk factor for hypertension, which is in turn a major risk factor for cardiovascular disease. Canadians consume approximately twice the daily Adequate Intake of sodium, most of which comes from processed foods. Enhancing nutrition labelling for sodium in the form of front-of-package (FOP) labels may help consumers select healthier products. This experimental study examined the efficacy of 4 types of FOP nutrition labels on participant selection of low versus high sodium products. 430 adults from the Waterloo Region were randomly assigned to one of 5 experimental conditions: (1) a control condition with no FOP label; (2) a basic numeric FOP label; (3) a numeric FOP label with “high” and “low” sodium content descriptors; (4) a detailed Traffic Light (TL) label with colour coding, content descriptors and numeric information; and (5) a simple TL label that did not include numeric information. Participants were shown pairs of grocery products that varied primarily in sodium content, and asked to select a free product. Selection of the low versus high sodium product served as the primary behavioural outcome; rankings and ratings of the experimental labels were also examined. Regression models were used to determine the relative efficacy of the 4 labelling formats, as well as the socio-demographic and diet and health-related predictors of these outcomes. Results indicated that participants in the FOP conditions with “low” and “high” sodium content descriptors (conditions 3, 4 and 5) were significantly more likely to choose the low sodium product compared to the control group. The detailed TL was ranked as the most effective at helping participants select low sodium products; this label was also rated significantly higher than other formats in liking, understanding and believability. Product selection did not differ significantly across socio-demographic groups, suggesting that FOP labelling might reduce the disparity in the use and understanding of nutrition labels among groups of varying socioeconomic status. This study has important policy implications. Results suggest that FOP labels should include content descriptors, which add prescriptive value and may help consumers select healthier products by improving understanding. TL labels, which incorporate content descriptors and colour coding, are recommended for future FOP labelling initiatives.