Life cycle assessment of niche oils with potential health benefits : a contribution to sustainable food systems in Switzerland

Feeding a growing global population with healthy and sufficient food from sustainable systems is a major challenge. Food contributes to about one third of global greenhouse gas emissions, especially through agriculture and land use. Promoting crop diversity is considered a key strategy to enhance the resilience and sustainability of food systems. This study assesses the environmental impacts of four niche oils produced in Switzerland—hemp seed oil, linseed oil, poppy seed oil, and pumpkin seed oil—and compares them with commonly consumed reference oils using a life cycle assessment (LCA) based on data from 12 farms. Two functional units are applied: FU1 (1 kg of cold-pressed oil) and FU2 (a recommended daily fat intake with an optimised fatty acid distribution). Environmental impacts are assessed using EF 3.1 midpoint indicators and aggregated with the Ecological Scarcity Method according to Frischknecht et al. (2021). A linear optimization model is used to evaluate environmentally optimal fat intake scenarios under nutritional constraints, allowing the relevance of niche oils to be assessed beyond environmental impacts by accounting for their nutritional composition. Under the product-based functional unit (1 kg of oil), environmental impacts differ substantially among the niche oils and are largely driven by nitrogen-related field emissions, with yield levels emerging as the key determinant. Linseed oil generally shows the lowest impacts, while hemp seed oil and poppy seed oil exhibit higher and more variable results. In contrast, the nutrient-based functional unit indicates that although niche oils are rich in polyunsaturated fatty acids, they are not prioritised in environmentally optimised intake scenarios due to the low absolute amounts required to meet daily fatty acid recommendations. However, under alternative dietary assumptions, such as a plant-based diet or diversification constraints, the relevance of niche oils increases. Overall, the results demonstrate that the relevance of niche oils depends on both agronomic performance and the nutritional recommendations underlying the analysis.