To effectively guide consumer purchasing behaviour, sustainability labels must deliver an unambiguous message, rather than remaining vague or abstract. In a new study that highlights the power of subtle design improvements, researchers from the Universities of Bonn, Newcastle (UK), and Corvinus (Hungary) examine the impact of minor visual modifications to the European Union’s organic label—commonly known as the “Green Leaf”. Their findings suggest that relatively minor changes can reduce consumer uncertainty, build trust in certified products, and ultimately enhance willingness to purchase. The results, now published online in the journal Agribusiness, offer practical insights into how more explicit signalling can support more sustainable food choices.

Sustainability certifications—such as organic, fair-trade, or animal welfare labels—are intended to assure buyers that a product adheres to specific ethical or environmental standards. However, many such labels fall short of this goal. According to Professor Dr Monika Hartmann, who leads the Department of Agricultural and Food Market Research at the University of Bonn, this is often because labels fail to attract sufficient attention, are too ambiguous, or even sow confusion. “Many labels fail to do so because they either don’t attract attention, aren’t clear enough, or even confuse,” Hartmann notes. The EU’s organic label, introduced in 2010 to unify the organic market across member states, serves as a case in point. Despite its mandatory status, a 2024 survey revealed that only 56 per cent of EU citizens recognise the Green Leaf logo, and fewer still (just 45 per cent) understand that it certifies compliance with EU organic regulations.

To investigate whether the EU logo’s communicative effectiveness could be improved, the researchers carried out a large-scale experiment spanning seven countries. The team tested two slight modifications to the Green Leaf design: in the first, they added the word “BIO” or “ECO” (depending on the local language) inside the star-bordered leaf symbol; in the second, they included both the language-specific term and the phrase “EU-certified”. More than 9,500 participants, grouped across the seven countries, were shown either the original label or one of the two altered versions. They were then asked to evaluate the labels in terms of clarity, trustworthiness, and perceived usefulness in supporting informed choices.

Across all participating countries, the results were consistent: both modified versions outperformed the original logo on every metric. Participants rated the revised labels as clearer, more trustworthy, and more helpful in identifying organic products. Surprisingly, the addition of the phrase “EU-certified” did not confer any added advantage. As Hartmann explains, “Interestingly, adding ‘EU‑certified’ had no extra effect. Apparently, the original logo mainly lacks the unmistakable signal that it denotes organic.” The key shortcoming, it seems, lies not in the absence of regulatory information, but in the lack of a recognisable, easily understood cue that a product is indeed organic.

A second study focused on Germany, involving around 500 participants, delved deeper into the psychological mechanisms behind these improved evaluations. This follow-up explored how design modifications influenced clarity, perceived uncertainty, trust, and behavioural intention. Hartmann, who is also affiliated with the University of Bonn’s Transdisciplinary Research Area “Sustainable Futures”, reported a marked increase in signal clarity. In this German sample, nearly 90 per cent of respondents correctly identified the modified label (with “BIO” or “ECO”) as denoting organic content, compared with fewer than 70 per cent for the original EU logo. While the direct impact of these changes on purchase intentions was not statistically significant, the study uncovered a crucial indirect effect: reduced uncertainty and heightened trust led to an increased likelihood of purchase, even if not consciously recognised as such by participants.

Taken together, the two studies present a compelling case for rethinking how sustainability labels are designed. The researchers emphasise that for labels to serve their intended purpose—helping consumers identify and choose sustainable products—they must be immediately recognisable and convey a clear, unambiguous message. When they fail to do so, even modest design interventions can yield substantial benefits. In this context, adding simple textual cues to an existing logo represents a low-cost, high-impact strategy to enhance transparency and improve consumer confidence. Given the urgent need to support sustainable consumption habits, these findings offer valuable guidance to policymakers, retailers, and certification bodies across Europe.

More information: Monika Hartmann et al, Enhancing Sustainability Label Effectiveness Through Logo Design Modification: An Analysis of the EU Green Leaf Logo, Agribusiness. DOI: 10.1002/agr.70013

Journal information: Agribusiness Provided by University of Bonn