Estimates of optimal supplies of animal-sourced foods differ by food system goal and socioeconomic context

Authors: WHITE, ROBIN - Virginia Tech; Hall, Mary Beth

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2024
Publication Date: 12/2/2024
Citation: White, R.R., Hall, M. 2024. Estimates of optimal supplies of animal-sourced foods differ by food system goal and socioeconomic context. Proceedings of the National Academy of Sciences (PNAS). https://doi.org/10.1073/pnas.2319011121.
DOI: https://doi.org/10.1073/pnas.2319011121

Interpretive Summary: A primary role of agriculture is to provide food, with a goal stated by the United Nations that it be done so that “the economic, social and environmental bases to generate food security and nutrition for future generations are not compromised”. Related to this, it is essential that such a food system provide all people globally with the opportunity to receive health-promoting diets. It has been recommended that consumption of animal-sourced food (ASF) be reduced in favor of plant-sourced food (PSF) in order to support desired environmental and human health outcomes, however, there is inconsistency in defining what roles exist for ASF in plant-based diets. Differing considerations and goals for human health, environmental impact, diet affordability, and geographic areas of concern used in food system analyses create substantial disconnects among approaches which contribute to drastically different conclusions related to ASF. Important distinctions in the nutrient availability from PSF and ASF; linkages among agricultural activities, food supply and availability; and complexities within food categories are often oversimplified or ignored. In work based on data spanning 150 countries, national per capita supplies of cereal grains and legumes were positively correlated to stunting in children, low birthweights, and anemia in reproductive age women, whereas ASF were negatively associated, except for lamb, game, and veal products. A challenge to making a direct interpretation on food categories with such information was that overarching any relationships of food categories was the percentage of the population unable to afford a healthy diet. This was highly correlated with the deficiency diseases and correlated with political instability of a nation. Other disconnects found included that food demands did not directly affect food production; food system dynamics are affected by economics and political stability. Evaluation of substituting different ASF for PSF to assess the impact on greenhouse gas emissions, ability of people to afford a healthy diet, and reducing nutritional deficiency diseases found that there are tradeoffs in achieving one versus another depending upon what substitutions are made. Based on these analyses, moderate ASF availability is essential to minimize nutritional diseases, though this comes with environmental tradeoffs. This work demonstrates that in our complex food system, food’s nutritional effects on diseases, food supply, economics and other factors all need to be considered as we seek situation-specific viable solutions.

Technical Abstract: Reduced consumption of animal-sourced food (ASF) has been recommended for environmental and human health objectives; however, ASF can be important for food security and diet affordability. We explored country-level relationships among various metrics of food supply, socioeconomic context, food security, diet affordability, and agricultural greenhouse gas emissions (GHGe) to characterize how optimal inclusion ranges for ASF vary with socioeconomic factors and food system goals. Data from 2015 to 2022 for 153 countries were sourced to generate Bayesian Networks representing relationships among the studied food system metrics. Networks were used in simulations to characterize optimal ASF inclusion to achieve environmental, food security, or diet affordability goals based on individual country data. Results are most appropriately interpreted in aggregate rather than as representations of specific countries due in large part to data limitations. Across countries simulated, median total ASF inclusion in the food supply to support food security, GHGe, or affordability objectives was 18.2% +/- 12.1%, 11.9% +/- 6.8%, and 17.6% +/- 8.5%, respectively. Joint optimization for these goals resulted in median ASF inclusion of 15.1% +/- 7.2%, with notable regional differences. Although ASF increases were supported in most developing regions, decreases were supported in developed countries. The reported SD in optimal ASF inclusion were considerable, and represented between-country variation. Empirical relationships of food categories to goals consistently favored dairy and egg products over meats. These results support previous literature highlighting the environmental intensity of ASF, but also indicate that moderate ASF supplies contribute to multiple food system goals simultaneously.