Assessing the Cost of Nutritionally Adequate and Low-Climate Impact Diets in Finland.

Background: Dietary changes form an important component of the sustainability transition of food systems but could be hindered by the cost of sustainable diets. Objectives: This study aimed to characterize the cost of nutritionally adequate and culturally acceptable diets with low-greenhouse gas emissions (GHGEs) in Finland. Methods: Two optimization models were built to find diets complying with nutritional and emissions requirements. The first model minimizes diet cost and the second one deviation from current diets. Both are calibrated to Finnish sociodemographic groups using dietary intake data, household budget survey data (for prices), and life cycle assessment coefficients (for GHGE). Three scenarios are simulated: "Health only" imposes only compliance with nutritional constraints, whereas "Health and GHGE-33%" and "Health and GHGE-50%" impose, in addition, minimum reductions in GHGE. Results: Minimum cost diets have a low-carbon footprint [-65% (-73%) for females (males)] and low cost [-69% (-73%) for females (males)] when compared with current diets but lack diversity and cultural acceptability. The more culturally acceptable health-only minimum deviation diets are marginally less costly and have a lower climate impact than baseline diets across all population groups. Reducing GHGE results in a substantial decrease in the cost of the minimum deviation diets. The lower cost of the minimum deviation diets with reduced GHGE results from both intercategory and intracategory substitutions. Conclusions: Affordability is not the key obstacle to the adoption of nutritionally adequate and lower GHGE diets, but cultural acceptability is. Reducing the climate footprint of diets can generate side benefits in terms of nutrition and affordability, which confirms that dietary change should be central to the sustainability transition of the Finnish food system. However, more attention should be paid to the issues of taste, convenience, social norms, and other aspects determining the cultural acceptability of sustainable diets.