Researchers call for labels to clear up confusion about sustainability and healthiness of foods

21 Dec 2023 --- Consumers often perceive healthy foods as sustainable, even when this is not reality. German researchers found no association between this perception and the actual link between a meal’s environmental sustainability and healthiness. This was unrelated to other characteristics such as vegan content, gender or eating style.

Nutrition Insight discusses this association between healthy and sustainable foods with the study’s authors — Dr. Gudrun Sproesser and Dr. Britta Renner, professors at the University of Konstanz, and Dr. Ulrike Arens-Azevedo, professor at the Hamburg University of Applied Sciences.

“Our results imply that it might be necessary to provide information to food consumers regarding both the sustainability and healthiness of foods to underline that these two dimensions can differ,” the authors tell us.  

“The benefits of heuristics are that they can reduce the time and effort to make decisions. This is useful given the numerous decisions that people need to make in everyday life. Dangers are that, in some contexts, heuristics can lead to systematic errors or ‘biases.’” 

However, they warn that with the healthy equals sustainable heuristic, “consumers might be misguided if only one dimension is labeled on foods and meals.” 

Rating meals  
For the study published in PLOS Sustainability and Transformation, 5,021 customers in a public university canteen rated the sustainability and healthiness of 29 meal options from one (lowest score) to six (highest score). 

The researchers also analyzed the recipes of each meal for their actual sustainability — based on material and carbon footprint — and healthiness — examining levels of calories, dietary fiber, fat, carbohydrates, sugar and salt. 

Respondents who perceived a meal as healthier saw it as more sustainable.While healthier foods can be produced using less eco-friendly methods and sustainable food can be less healthy, the respondents seemed to rely on a “health equals sustainability” heuristic. 

For example, participants scored a vegan “creamy mushroom soup,” “chicken breast cutlet” and pork “curry Bombay” at a 3-3.5 on both sustainable and healthy ratings. Meanwhile, these three meals were among the least environmentally sustainable and were healthier than the study participants perceived them to be. 

At the same time, participants rated environmentally-friendly vegetarian “baked spring rolls” much lower in sustainability and healthiness than they are. 

“If respondents perceived a meal as healthier, they also perceived it as more sustainable,” reads the report. “This association was comparable between meals with highly similar actual environmental sustainability and healthiness scores and meals with very dissimilar actual scores.” 

Introducing food labels 
The researchers suggest that food labels provide consumers with information on food’s environmental sustainability and healthiness. 

“The fact that many researchers have pointed toward the generally low level of knowledge among consumers about the sustainability of foods speaks in favor of the introduction of a sustainability label on foods, not only in supermarkets but also in other food purchasing contexts, such as restaurants or canteens,” explain Sproesser, Renner and Arens-Azevedo.  

They highlight that many countries have already implemented healthiness labels for pre-packed foods, such as the Nutri-Score used in several EU member states. “Such labels might have the potential to promote healthy eating also in canteen contexts.” 

“About the potential effectiveness of sustainability labels, a recent review revealed that ecolabels can promote the selection, purchase and consumption of more sustainable food and drinks.” 

The authors suggest that politics, scientific research, respective societies (e.g., nutrition societies) and the industry should lead in providing this information to consumers. 

Earlier this week, researchers suggested changing food labels from “vegan” or “plant-based” to “healthy” or “sustainable,” as this may encourage people to eat more plant-based foods. They explained that US citizens have negative connotations with the word “vegan,” although they are increasingly concerned about eating healthy and environmentally friendly foods. 

The researchers suggest that food labels may provide consumers with information on a food’s sustainability and healthiness.Cause and effect
The research team also speculates whether a “halo” effect exists between healthiness and sustainability — where a favorable impression in one aspect promotes good evaluations of unrelated dimensions. 

As people are generally more familiar with health-related indicators and diet quality, the authors argue that there might be a halo effect from healthiness toward sustainability. For example, earlier research found that people perceived foods as healthier with an organic label. 

Moreover, the study found a higher correlation between actual and perceived sustainability than between real and perceived healthiness. 

At the same time, the authors note that third factors may have influenced how people scored meals, such as individual differences in using comparison standards, response styles or understanding the scales. They recommend future research to use alternative designs, such as different health labels on foods, to determine how these affect perceived sustainability. 

Meanwhile, scientists point to a gap in understanding healthy and sustainable diets among consumers, which research aims to fill. Companies also need support communicating to consumers how their products are healthy or sustainable. 

“More data needed” 
The authors note several limitations to the current study. For example, it was impossible to conduct a thorough control of confounding variables. The sample of German students means the findings may not be generalized to other groups and more indicators may be needed to assess food sustainability. Participants also may have chosen meals they like, which could result in reporting more positive perceived scores. 

Sproesser, Renner and Arens-Azevedo hope the study will stimulate further research and public interest. “For instance, more data is needed on the actual sustainability of foods and meals that is easily available to the public.” 

They note that research has also demonstrated associations between “perceived healthiness and naturalness as well as organic and clean labels.”  

The authors explain that using similar cues may partly explain the source of these heuristics. 

“Concerning the healthy equals sustainable heuristic, our study showed that the actual meal healthiness and environmental sustainability scores or vegan meal content did not serve as joint cues for perceived sustainability and healthiness and, thus, a trigger for this association.” 

“Future research needs to study whether there are other cues than those investigated in our study, such as green meal color, that act as a source for the healthy-sustainable heuristic.”

By Jolanda van Hal