A nutritional display policy such as the Nutri-score has an effect on the nutritional quality of what the consumer puts in their food basket. Carried out separately, a pricing policy also encourages consumers to make healthier purchases, although the effect is less. But the effect of the two policies does not add up, according to an experimental study carried out by researchers at Inrae.
Information and prices, two incentive tools
“To encourage consumers to buy products that are more beneficial to their health, public authorities use two types of incentive tools in particular: information (nutritional display) and prices (taxes and subsidies), underlines a press release from the 'INRAE published on December 19, 2024. Numerous studies have measured the effectiveness of variants of each of these policies taken separately. Little has been done on the effectiveness of their combination. »
Inrae researchers, specializing in applied economics, tested the complementarity of these two incentive tools on 386 Grenoble residents, representative of the diversity of the French population. “By browsing a virtual grocery store, they had to fill their food basket twice, choosing from 290 commercial products.” For the first time, the consumer browsed the grocery store without a policy, thus constituting a reference food basket. The second time, one of the tested policies or both combined was implemented, which allowed the researchers to measure the change induced in relation to the first basket.
The two policies were compared separately: on the one hand, the Nutri-score display policy alone and on the other hand, the pricing policy alone. In the latter case, researchers apply a 10% tax on products rated D in the Nutri-score, a 20% tax on E products, while a 10% subsidy is granted on B products and a subsidy of 20% on products rated A. This pricing policy is explicitly presented to the consumer, since the price after the policy is displayed next to the old price, which is crossed out. After studying the two policies separately, the researchers studied the two types of policies combined.
Score has more effect than monetary incentive
The results of the study were published on December 19 in Journal of Economic Behaviour and Organizationan international research journal. The nutritional quality of the basket is assessed using a score developed in the United Kingdom, the FSA for Food Standards Agency. The FSA score is between -15 and +35, knowing that the lower the number, the better the nutritional quality.
In the experiment conducted with Grenoble consumers, the average basket without policy obtained an FSA score of 3.1. The display of the Nutri-score makes it possible to significantly improve the nutritional quality of the basket by reducing the score by 2.67 points between the two baskets. In comparison, an explicit pricing policy only lowers the basket score by 1.86 points. With the best combination of the two policies, the score difference is on average 3.23 points.
“By combining Nutri-Score with this pricing policy, the nutritional quality of purchases is not significantly improved compared to Nutri-Score alone […]. The effects of these two policies are therefore not additive. Consumers here react more to normative messages than to monetary incentives. »
No tax costs for the Nutri-score
The researchers also note in this study that “economically, these different food policies have little impact on household food budgets”. However, they measure that the Nutri-score incentive policy slightly increases the price per calorie of the average basket, by €0.22 for 2,000 kcal purchased.
As for the cost to the State of these policies, the researchers estimated it by extrapolating the data from their study to household consumption over one year (total annual public spending on subsidies – total annual fiscal gains from taxes). The cost of the Nutri-score for the State is zero. On the other hand, “the tax cost amounts to €233 per household per year with a policy of significant price changes”.
Audrey Dibet
