Sustainability dimensions of diets with varying levels of food biodiversity in the NutriNet-Santé study

Objective: Dietary diversity is associated with health benefits. However, food biodiversity has been understudied. Therefore, we aim to evaluate the associations between dietary species richness (DSR), i.e., the number of species consumed by individuals, and dietary sustainability dimensions, including environmental pressures, diet quality and monetary cost. Setting: The study was carried out among the NutriNet-Santé cohort. Participants: 29,173 volunteers were included. Design: Participants completed a 264-item food frequency questionnaire. Food items were linked to the corresponding species. ANCOVA models were fitted to evaluate the associations between total, plant, animal DSR, and dietary sustainability dimensions. The dietary share of organic food was computed. Results: Higher DSR was associated with lower overall environment impact, captured by the pRecipe, an indicator including greenhouse gases emissions (GHGe), land occupation (LO) and cumulative energy demand (CED) (pRecipe, Q5 vs Q1, -8.5%), better diet quality, reflected by the level of adherence to the French dietary guidelines (sPNNS-GS2, Q5 vs Q1: +44.8%), and stable dietary cost. Higher plant DSR was related with lower environmental impacts, better diet quality, and higher monetary cost. Higher animal DSR was associated with higher environmental pressures, lower diet quality and monetary cost. The amount of organic food consumed was positively associated with plant DSR, and negatively associated with animal DSR. Conclusions: Overall, more biodiverse diets were related with better diet quality and lower environmental pressures. The associations seemed to be driven by plant biodiversity. Further studies are warranted to better understand the relationship between food biodiversity and sustainability dimensions across settings.