Abstract
ABSTRACT: Livestock farming incurs large and varied environmental burdens, dominated by beef. Replacing beef with resource efficient alternatives is thus potentially beneficial, but may conflict with nutritional considerations. Here we show that protein-equivalent plant based alternatives to the beef portion of the mean American diet are readily devisible, and offer mostly improved nutritional profile considering the full lipid profile, key vitamins, minerals, and micronutrients. We then show that replacement diets require on average only 10% of land, 4% of greenhouse gas (GHG) emissions, and 6% of reactive nitrogen (Nr) compared to what the replaced beef diet requires. Applied to 320 million Americans, the beef-to-plant shift can save 91 million cropland acres (and 770 million rangeland acres), 278 million metric ton CO2 and 3.7 million metric ton Nr annually. These nationwide savings are 27%, 4%, and 32% of the respective national environmental burdens.
Generated Summary
This research article presents a study that uses a combination of Monte Carlo sampling and linear programming to devise plant-based alternatives to the beef portion of the American diet. The study aims to minimize resource use while satisfying key nutritional requirements. The analysis involves constructing diets with various combinations of plant items, optimizing for environmental impact (land use, greenhouse gas emissions, and reactive nitrogen use), and evaluating nutritional characteristics. The study uses data from the United States Department of Agriculture (USDA) to define the Mean American Diet (MAD) and calculates the environmental and nutritional impacts of replacing the beef portion with plant-based alternatives. The approach seeks to create diverse and nutritionally adequate solutions that reflect real-world dietary choices. The study then compares the resource needs and nutritional profiles of the plant-based diets with those of the beef-inclusive MAD.
Key Findings & Statistics
- The beef-to-plant shift can save 91 million cropland acres (and 770 million rangeland acres), 278 million metric ton CO2 and 3.7 million metric ton Nr annually. These nationwide savings are 27%, 4%, and 32% of the respective national environmental burdens.
- The study found that plant-based diets require on average only 10% of land, 4% of greenhouse gas (GHG) emissions, and 6% of reactive nitrogen (Nr) compared to what the replaced beef diet requires.
- U.S. beef yields at most 250 Mcal ac⁻¹ y⁻¹. By comparison, high fructose corn syrup yields 4200 Mcal ac⁻¹ y⁻¹.
- For the calculations, the study updated earlier papers including updating feed composition based exclusively on NRC data.
- To evaluate plant-based replacement to beef, the study constructed diets comprising combinations of plant items that adequately replace the beef portion of the MAD. The study devised these varied alternative diets by employing Monte Carlo sampling and linear programming.
- The starting point of each Monte Carlo realization is the random choice of a set of 60 plant items out of the full list of 65 considered items.
- The study randomly chose 500 plant combinations (out of over 8 million options) and for each found the set of 60 item-specific masses that jointly minimize either land use, GHG emission or reactive nitrogen use (Nr) while satisfying the four inequality constraints.
- The saved high quality cropland acreage nearly equals the ≈91 million total national corn acreage. The almost 0.8 billion acres of spared pastureland represent 40% of the contiguous US land surface area, more than the combined area of the three largest states, Alaska, Texas and California.
- The ≈3.7 million metric tons of Nr savings constitute 33% of the total national N fertilizer use, and twice the Mississippi N delivery into the Gulf of Mexico.
- The ≈278 million metric tons CO2e averted emissions represent 4% and 47% of the U.S. total and direct agricultural (excluding uncertain emissions related to land use changes) emissions.
Other Important Findings
- The study found that the leading items in the plant-based beef replacement diets, such as peanuts, lentils, or kidney beans, are consistent with authoritative nutritional advice.
- The study showed that affordable, commonly used, and nutritionally equivalent or better plant items dominate the optimized diets.
- The plant-based diets chosen supply no vitamin B12, while the replaced beef supplies 1.7 µg, 71% of the full recommended adult daily intake. Similarly, beef supplies ≈68% more monounsaturated fatty acids, generally regarded as protective.
- The replaced and replacement diets are essentially interchangeable in terms of vitamins B₂ and B₆.
- The plant-based replacement diets also supply 15 g or 57 kcal carbohydrates daily.
- The study suggests that this dietary shift can significantly mitigate several major national environmental challenges, such as the Gulf of Mexico Dead Zone, and multifaceted damage to semiarid western lands.
- The study suggests that the spared 92 million crop acres will be able to support much additional production of fruit, vegetables, grain or legumes for direct human consumption.
Limitations Noted in the Document
- The study acknowledges that while excess calories are rampant in the U.S., caloric deficit is practically nonexistent. The bound on calories might be 4% inflated, but is necessary for consistency, and has virtually no impact on the findings.
- The study’s environmental analysis does not address all relevant environmental impacts.
- The study does not fully address all relevant environmental impacts, and thus further developing performance metrics, especially ones combining nutritional, environmental and other societal objectives, is essential for devising coherent, readily mutually comparable results and for identifying synergies and trade-offs among varied environmental objectives.
- The study notes that the deployment prospects of the explored shift may be limited.
Conclusion
This research provides strong evidence that replacing the beef portion of the American diet with plant-based alternatives is feasible and offers substantial environmental and nutritional benefits. The study demonstrates that plant-based diets can significantly reduce land use, greenhouse gas emissions, and reactive nitrogen use, all while providing a nutritionally adequate alternative. The findings highlight the potential for large-scale environmental benefits, including reduced pressure on land resources and mitigation of major environmental challenges such as the Gulf of Mexico Dead Zone. The study shows that the chosen plant-based diets align with authoritative nutritional advice and can be readily deployed, with leading items like peanuts, lentils, and kidney beans being both affordable and widely available. Although the plant-based diets may be deficient in certain nutrients like vitamin B12, these deficiencies can be easily addressed with supplements. The study also notes that the shift to plant-based diets can improve nutrition in most metrics. The savings in high-quality cropland and the potential for restoring vast rangelands are significant. The study acknowledges the need for further research into the social and economic ramifications of a dietary shift and the importance of consumer responses. The study provides a foundation for promoting sustainable dietary practices and underscores the potential of plant-based diets to enhance both human and environmental health. It serves as a call for devising coherent, readily comparable results and for identifying synergies and trade-offs among varied environmental objectives to make the shift a successful one. This work advocates for a transition towards sustainable dietary patterns, showcasing how shifting from beef to plant-based diets can create meaningful gains in both human health and ecological well-being. The findings are particularly pertinent in light of ongoing environmental degradation. The study’s focus on practical, readily achievable dietary changes, makes it especially valuable. The study underscores the potential of informed food choices to contribute to a healthier planet.