Temporal Trends in Greenhouse Gas Emissions, Water Footprint, and Ecological Footprint of Food Purchases in Brazilian Metropolitan Areas From 1987 to 2017

Background: We aim to assess the temporal trends in greenhouse gas emissions (GHGE), water footprint (WF), and ecological footprint (EF) of food purchases, and how these depend on the amount of food processing. Methods: We have used data from five Brazilian Household Budget Surveys (1987, 1996, 2003, 2009, 2017). We calculated GHGE, WF, and EF per 1000 kcal. Food items were classified into NOVA food groups – unprocessed/minimally processed (G1), processed culinary ingredients (G2), processed foods (G3), and ultra-processed foods (G4). Linear regression was performed to evaluate trends of the environmental impacts across the years. Findings: In 30 years, GHGE, WF and EF have increased by 21%, 22% and 17% respectively, to 1886 g CO2 eq / 1000 kcal, 1769 L / 1000 kcal and 11·4 m 2 /1000 kcal. We found a significant variation of these trends between different levels of processing, which were generally stronger for the higher levels of processing. The environmental indicators for G1 have not changed over time. The GHGE from G2 decreased by 18% (p-trend<0·001), while the GHGE from G4 increased by 245% (p-trend<0·001). The WF also decreased for G2 (by 17%, p-trend<0·001) and increased for G4 (by 233%, p-trend<0·001). The EF from G2 decreased by 13% (p-trend<0·001), while the EF from G3 and G4 increased by 49% and 183%, respectively (both p-trend<0·001). Interpretation: The environmental impacts of the Brazilian diet have increased over the last three decades along with increased impacts from ultra-processed foods. Funding Statement: Science and Technologies Facilities Council - Global Challenges Research Fund. Declaration of Interests: The authors have no conflicts of interest to disclose.