An analysis integrating the findings from 134 studies on the impact of colour-coded nutrition labels, and warnings, found on the front of some food packaging, indicating that these labels do indeed appear to encourage more healthful purchases. Doctoral researcher, Jing Song, of Queen Mary University, London, and colleagues presented these findings in the open-access journal PLOS Medicine.
Some countries have introduced mandatory front-of-package labelling in hope of improving people’s diets and reducing the burden of diseases associated with poor diets. These labels may employ colour coding to indicate nutrition, or they may warn consumers about unhealthful features of products. However, studies on the impact of such labelling have produced mixed evidence.
To help clarify the impact of front-of-package nutrition labels, Song and colleagues analysed data from 134 peer-reviewed studies published between January 1990 and May 2021. They applied an analytical method known as ‘network meta-analysis’ in order to integrate the results of the studies and evaluate the impact of four different labelling systems—two that use colour-coding and two that use warnings.
The analysis also highlighted psychological mechanisms that may underlie the different strengths of different labels, due to their impact on consumers’ understanding of nutrition information and resulting changes in attitudes towards unhealthful or healthful foods. Colour-coded labels appeared to be more beneficial in promoting more healthful purchases, and warning labels were more effective in discouraging unhealthy purchases.
This meta-analysis showed that all four labelling systems appeared to be advantageous in encouraging consumers to purchase more nutritionally beneficial products. Evaluation of specific nutritional qualities found that labelling nudged consumers towards foods and drinks with lower levels of energy, sodium, fat, and saturated fat.
These findings could help guide and refine policies on front-of-package labelling to improve public health. Meanwhile, future research could build on this study by addressing related concepts, such as the impact of labelling on reformulation of products by the food industry or more long-term benefits of labelling on purchasing behaviour.
“This study found that colour-coded labels and warning labels are all able to direct consumers towards more healthful purchase behaviour. Colour-coded labels can promote the purchase of more healthful products, while warning labels discourage the purchase of less healthful products.” the researchers said.