Writing in the journal Appetite, the research team noted that many nutritional labelling schemes differ in the nature of, and extent to, which they provide reference points for specific nutrients. Nutrient tables, for example, only provide absolute content levels and no reference point information, while GDA and traffic light labelling (albeit in different formats) provide nutrient-level reference points.
Led by Erica van Herpen from Wageningen University, The Netherlands, the research team examined the ability of different types of nutrition labelling schemes (such as multiple traffic light label, nutrition table, GDA, and logos) to communicate product healthfulness:
- across different product categories,
- between options from the same product category,
- when viewed in isolation and in comparison with another product.
The team reported that only a labelling scheme with reference point information at the nutrient level can achieve all three objectives.
"Across both studies, the multiple traffic light label appears effective in communicating the healthfulness of products, as this label is able to communicate healthfulness both across and within product categories, and for products evaluated in isolation as well as in comparison with another product," said van Herpen and her colleagues.
"Although other types of labelling schemes are also capable of communicating healthfulness, labelling schemes lacking reference point information are less effective when no comparison product is available, and labelling schemes based on overall product healthfulness within the category (e.g., logos) can diminish consumers’ ability to differentiate between categories, leading to a potential misinterpretation of product healthfulness," they wrote.
Published online ahead of print, doi:10.1016/j.appet.2013.10.012
"Inferring Product Healthfulness from Nutrition Labelling: The Influence of Reference Points"
Authors: Erica van Herpen, Sophie Hieke, Hans C.M. van Trijp