To examine consumers’ ability to correctly interpret front-of-package (FOP) ‘high in’ warnings in the presence of a voluntary claim for the same or a different nutrient.

A between-group experimental task assigned respondents to view food products labelled as ‘high in sodium’, with a ‘reduced sodium’ claim positioned next to the warning, away from the warning or absent. A second experiment assigned participants to view a food product labelled as ‘high in sugar’, with a ‘reduced fat’ claim positioned next to the warning, away from the warning or absent. For both tasks, respondents were asked to identify whether the products were high in the indicated nutrient.

Online survey (2016).

Canadians aged 16–32 years (n 1000) were recruited in person from five major cities in Canada.

Respondents were less likely to correctly identify a product as ‘high in sodium’ when packages also featured a voluntary ‘reduced sodium’ claim, with a stronger effect when the claim was positioned away from the FOP symbol (P<0·001). The number of correct responses was similar across conditions when the nutrient claim was for a different nutrient than the one featured in the FOP ‘high in’ warning.

The findings demonstrate that the presence of a voluntary nutrient claim can undermine the efficacy of mandated FOP labels for the same nutrient. Countries considering nutrient-specific FOP warnings, including Canada, should consider regulations that would prohibit claims for nutrients that exceed the threshold for nutrient-specific FOP warnings.