Background and objective:
Food biodiversity has intrinsic potential to underpin diverse, healthy diets and improve Earth system resilience. However, there is limited work on methods that capture the diversity of species in human diets through national surveys. This study presents a multi-step approach for identifying the food biodiversity that underlies Brazilian diets.

Methods:
A sequential, five-step approach, determined _a priori_, was followed to identify the plant and animal species that underlie Brazilian diets: 1 - Household data retrieval, 2 - Unique food item identification and compilation, 3 - Classification of food items according to the Nova food classification system, 4 - Identification of species (single- and multi-ingredient items), 5 - Linking identified species back to household data. Data from the 2017-18 Household Budget Survey were used to identify all foods and beverages purchased by household aggregates (n=575). Food items were classified according to the Nova classification system into four groups: 1) unprocessed or minimally processed foods, 2) processed culinary ingredients, 3) processed foods, 4) ultra-processed foods. Food items classified as Nova groups 1 and 2 were identified at the species level by using taxonomical classification from four data sources. Ingredient lists from the UNC/IDEC/NUPENS national food label database were used to determine the composition of processed and ultra-processed foods.

Results:
Brazilian households acquired 1,866 unique food items: 49.8% unprocessed/minimally processed foods, 4.2% culinary ingredients, 10.2% processed foods and 35.8% ultra-processed foods. A total of 234 plant and 127 animal species were identified. The number of plant and animal species underlying the Nova food groups were: G1=227, G2=21, G3=19, G4=26; and G1=125, G2=4, G3=6, G4=5, respectively.

Conclusion:
This study adds new evidence on methods to operationalise and measure the food biodiversity in diets, as well as an approach to measure the impacts of foods purchased/consumed at the household level on biodiversity.