A growing body of research suggests that consumers’ nutritional understanding is helped by front-of-pack green, red and yellow colours for different nutrients, such as sugar, salt, saturated fat and calories. However, the issue has been the subject of intense debate. The European food industry has claimed it could fragment the EU internal market, and the European Commission has opened proceedings against the UK traffic light system after it received complaints from industry that it could affect marketing of their products.
This latest research, performed at the Life & Brain Centre in Bonn, observed brain activity as 35 participants assessed nutrition labels on products like chocolate, yoghurt and frozen meals, either presented as grams and percentages per portion, like labels currently used across Europe, or in colour coded ‘traffic light’ form.
Study participants then were asked how much they would pay for each item. The researchers found they were willing to pay more for a product carrying a green traffic light label compared to the same product carrying nutrition labelling alone. They also found red labels meant participants were willing to pay significantly less for products than when they lacked colour coded information.
"You can conclude that the traffic light label acts as a reinforcer,” said first author Laura Enax of the Centre for Economics and Neuroscience at the University of Bonn. “The health relevance of the ingredients is weighed more heavily into purchasing decisions compared to simple nutrition information.”
Additionally, as participants thought about how much they were willing to pay, different areas of the brain were active depending on the traffic light label. Red labels were linked to a part of the brain associated with self-control in food choice, while green labels activated a part of the brain linked to reward expectation – possibly the expectation of beneficial health outcomes, the study’s authors suggest.
Professor Weber, also of CENs at the University of Bonn, said: “The traffic light label appears to enable the study participants to better resist unhealthy foods compared to a label containing the traditional information on grams and percentages of the particular ingredients. A traffic light label probably implicitly increases the weight consumers place on healthiness in their decision.”
Published online ahead of print DOI: 10.1002/oby.21027
“Nutrition labels influence value computation of food products in the ventromedial prefrontal cortex”
Authors: Laura Enax, Yang Hu, Peter Trautner and Bernd Weber