(P02-003-23) The Impact of Substituting Animal With Plant Protein Foods on Diet-Related Greenhouse Gas Emissions, Nutrition, and Health Outcomes: A Systematic Review of Modeling Studies

Objectives: Dietary guidelines are placing emphasis on plant-based diets due to their inverse relationship with disease, however, the population-level impact of substituting animal with plant protein foods on a combination of diet sustainability dimensions is not known. Our objective was to assess changes to diet-related greenhouse gas emissions (GHGE) and nutrition or health outcomes stemming from modeled replacements of animal with plant protein foods in self-selected diets.

Methods: The search was run on 16 January 2023 in PubMed, Scopus, and EMBASE. Studies were considered eligible if they modeled substitutions of meat or dairy with plant protein foods (nuts, seeds, legumes, and soy-based foods and beverages) using individuals’ dietary data and included information on GHGE with or without nutrition or health outcomes. We compared changes to GHGE, the percentage of the population below recommendations for nutrients of public health concern, and mortality risk between observed and modeled diets.

Results: Nine articles were identified, four of which assessed either nutrition or health outcomes. Most studies substituted meat (red, poultry, and processed) or beef with plant protein foods. Replacing up to 50% of meat decreased GHGE by 12-29% and was associated with a 6% lower mortality risk. Partially substituting beef decreased GHGE by 10-20% and reduced the percentage of the population below recommendations for calcium and fibre by 6% and 2%, respectively. Substituting 30% of meat and dairy reduced GHGE by 14% and decreased the percentage of pre-menopausal females below iron requirements by 8-10%, although no data was available for calcium or fibre. Substituting milk or cheese led to smaller reductions of GHGE (2-4%), but studies did not capture nutrition or health data.

Conclusions: Partially substituting meat, particularly beef, with plant protein foods had a synergistic beneficial effect on environmental, nutrition, and health outcomes. Future studies must consider an interdisciplinary approach that assesses the impact of dietary substitutions on multiple facets of diet sustainability to better inform food policy and dietary guidance in facilitating the shift towards healthy and sustainable diets.

Funding Sources: OA is supported by a doctoral scholarship from SSHRC.