How to communicate the healthiness and sustainability of foods to consumers?

**Background:** Climate change is a pressing global issue, and accumulating evidence links healthy diets to environmental sustainability. This raises the need to educate consumers using simple tools applied directly to food packaging. Front-of-pack labels (FOPLs) have been designed for ease of reading to help customers make informed food choices, but the question remains open on how features of food quality, nutritional value, and sustainability can be combined and integrated. The authors present a graphical abstract summarizing messages conveyed by 12 different food label categories.

**Methods:** This is a letter to the editor commenting on the article by Clark et al., who developed a tool for calculating the environmental impact of packaged food without performing lengthy life cycle assessments. Clark et al. attempted to combine their newly developed environmental score with a nutritional score based on the Nutriscore. The present authors analyze the resulting figure (figure #4 on page 7 of Clark et al.) and critique the methodology used.

**Key Results:** The authors note that given numerous retrospective studies on the relationship between Nutriscore labeling and healthy individual dietary patterns, they would have expected low-impact healthy foods to occupy the bottom-left quadrant of the combined plot, while high-impact unhealthy foods occupy the top-right quadrant. However, food categories appear to be distributed in a cloud-like shape, making interpretation difficult. The authors attribute this to the dietary score being computed on a 100-g scale reference, which does not accurately mirror actual consumption in the dietary pattern (which is a product of portion size by frequency). They argue this may not yield conclusive results, citing the close relationship between some healthy diets (e.g., the Mediterranean diet) and a low-carbon footprint that has been well studied.

**Clinical Implications:** The purpose of this letter is to reopen a scientific debate, first addressed more than a decade ago by Scarborough et al., to develop new methods for communicating information to consumers in a simple, intuitive, and scientific fashion. The authors emphasize that future research should focus on understanding whether and how existing FOPLs can convey additional messages; otherwise, using multiple labels on the package may compromise the intuitiveness and simplicity that are the main strengths of these tools. This has implications for public health nutrition policy and consumer education regarding both dietary quality and environmental sustainability.