Abstract
What we eat greatly influences our personal health and the environment we all share. Recent analyses have highlighted the likely dual health and environmental benefits of reducing the fraction of animal-sourced foods in our diets. Here, we couple for the first time, to our knowledge, a region-specific global health model based on dietary and weight-related risk factors with emissions accounting and economic valuation modules to quantify the linked health and environmental consequences of dietary changes. We find that the impacts of dietary changes toward less meat and more plant-based diets vary greatly among regions. The largest absolute environmental and health benefits result from diet shifts in developing countries whereas Western high-income and middle-income countries gain most in per capita terms. Transitioning toward more plant-based diets that are in line with standard dietary guidelines could reduce global mortality by 6–10% and food-related greenhouse gas emissions by 29–70% compared with a reference scenario in 2050. We find that the monetized value of the improvements in health would be comparable with, or exceed, the value of the environmental benefits although the exact valuation method used considerably affects the estimated amounts. Overall, we estimate the economic benefits of improving diets to be 1–31 trillion US dollars, which is equivalent to 0.4–13% of global gross domestic product (GDP) in 2050. However, significant changes in the global food system would be necessary for regional diets to match the dietary patterns studied here.
Generated Summary
This research presents a region-specific global health model to assess the health and environmental impacts of dietary changes, linking these aspects with emissions accounting and economic valuation. The study evaluates the consequences of dietary shifts towards less meat and more plant-based foods across different regions. Employing a comparative risk assessment model, the research estimates age- and region-specific mortality related to dietary and weight-related risk factors. The study integrates emissions accounting and economic valuation modules to quantify the health and environmental consequences of dietary changes. The analysis encompasses various dietary scenarios, including a reference scenario based on FAO projections, a scenario aligning with global dietary guidelines, and scenarios featuring vegetarian and vegan diets. The core methodology involves linking regional food consumption data to greenhouse gas (GHG) emissions and health outcomes, while also considering the economic value of these changes through health and environmental impact assessments. The study underscores the significant benefits of dietary changes, particularly in developing countries, and the economic implications of these shifts, which are compared with environmental benefits. The aim is to estimate the economic benefits of improving diets, providing insights for policy makers and researchers to understand the potential impact of dietary changes on health, the environment, and the economy.
Key Findings & Statistics
- The food system is responsible for over a quarter of all GHG emissions.
- High consumption of red and processed meat and low consumption of fruits and vegetables are important diet-related risk factors.
- Without targeted dietary changes, the situation is expected to worsen as a growing and more wealthy global population adopts diets resulting in more GHG emissions.
- Transitioning toward more plant-based diets could reduce global mortality by 6-10% and food-related greenhouse gas emissions by 29-70% compared with a reference scenario in 2050.
- The study estimates the economic benefits of improving diets to be 1-31 trillion US dollars, equivalent to 0.4-13% of global GDP in 2050.
- Adoption of global dietary guidelines (HGD) would result in 5.1 million avoided deaths per year [95% confidence interval (CI), 4.8-5.5 million] and 79 million years of life saved (CI, 75-83 million).
- Vegetarian (VGT) diet: 7.3 million avoided deaths (CI, 7.0-7.6 million) and 114 million life years saved (CI, 111–118 million).
- Vegan (VGN) diet: 8.1 million avoided deaths (CI, 7.8-8.5 million) and 129 million life years saved (CI, 125-133 million).
- More than half of avoided deaths (51-57% across the three scenarios) were due to decreased red meat consumption.
- 24–35% to increased fruit and vegetable consumption.
- 19-30% to a lower prevalence of being overweight and obese.
- Reduced mortality in the VGT and VGN scenarios compared with the HGD scenario was due to lower red meat consumption (1.7 million additional avoided deaths in each) and higher fruit and vegetable consumption (VGT, 0.8 million; VGN, 1.8 million additional avoided deaths).
- About 45-47% of all avoided deaths were from reduced coronary heart disease (CHD), 26% from stroke, 16-18% from cancer, and 10-12% from type 2 diabetes mellitus (T2DM).
- Adopting the nonreference diets reduced the combined number of deaths per year from CHD, stroke, cancer, and T2DM in 2050 by 12% (HGD), 17% (VGT), and 19% (VEG) and the overall number of deaths from all causes by 6% (HGD), 9% (VGT), and 10% (VEG).
- The greatest number of avoided deaths (~72% across the three nonreference scenarios) occurred in developing countries, in particular in East Asia (31-35%) and South Asia (15-19%).
- Red meat consumption was the risk factor that had the most positive effect on health in East Asia (78-82%), Western high- and middle-income countries (64–71%; 58–65%), and Latin America (42-48%).
- In the HGD scenario, the changes include increasing global fruit and vegetable consumption by 25% (99 g.d−1) and by more in Sub-Saharan Africa (190%, 323 g.d−1), South Asia (101%, 248 g.d−1), and Latin America (39%, 138 g.d−1) and decreasing global red meat consumption by 56% (42 g.d−1), and by more in Western high-income and middle-income countries (78%, 113 g.d−1 and 69%, 72 g.d-1, respectively), East Asia (74%, 93 g.d−1), and Latin America (72%, 83 g.d−1).
- Compared with the reference scenario, the alternative diets require 15% less total energy intake.
- In the HGD scenario, food-related GHG emissions were 8.1 ± 0.1 Gt-y−1, which is 29% less than REF emissions in 2050 and 7% greater than emissions in 2005/2007.
- The two vegetarian diets resulted in food-related GHG emissions at midcentury (VGT, 4.2 ± 0.1 Gt-y−1; VEG, 3.4 ± 0.1 Gt-y−1) that were 45-55% lower than the 2005/2007 levels and 63-70% lower than REF emissions.
- In the HGD scenario, emissions reductions were largely attributable to reduced red meat consumption (3.2 ± 0.1 GtCO2, 97%).
- Reductions in red meat (6.1 ± 0.1 GtCO2, 85%) and poultry (1.08 ± 0.01 GtCO2, 15%) were responsible for lower VGT emissions, and lower consumption of red meat (76%), poultry (13%), and eggs and dairy (1.2 ± 0.03 GtCO2, 15%) for lower VGN emissions.
- The health-related cost savings of moving to the diets based on dietary guidelines (HGD) will be 735 billion US dollars per year ($735 billion-y−1) in 2050 with values in the range $482–987 billion-y−1.
- Greater savings occur with the adoption of vegetarian diets (VGT, $973 billion-y, range $644-1,303 billion-y) and vegan diets ($1,067 billion-y−1, range $708-1,426 billion-y−1).
- The value-of-statistical-life approach led to much higher estimates of the economic benefits associated with dietary change.
- The monetized value associated with diet-related changes in mortality amount to 21 trillion (or 1012) US dollars per year ($21 trillion-y−1) in 2050 with a range (again reflecting uncertainties in the methodology) of $10-31 trillion-y−1.
- The values for the VGT diet are $28 trillion-y−1 ($14–42 trillion-y−1), and for the VGN diet $30 trillion-y−1 ($15-46 trillion-y−1).
- The benefits amounted to 0.10% (0.04–0.32%) for HGD diets, 0.22% (0.08–0.69%) for VGT diets, and 0.25% (0.09–0.77%) for VGN diets.
- For the year 2050, the SCC estimates are 27, 71, 98, and 221 US dollars·ton−1 of CO2 for discount rates of 5%, 3%, and 2.5%, and the 95th percentile at a 3% discount rate.
Other Important Findings
- The choices about food affect both health and the environment.
- High consumption of red and processed meat and low consumption of fruits and vegetables are important diet-related risk factors contributing to substantial early mortality.
- Changing diets may be more effective than technological mitigation options for avoiding climate change.
- The study uses a region-specific global health model to link the health and environmental consequences of changing diets.
- The model considers red meat, fruits, vegetables and total energy consumption.
- The greatest benefits of dietary change occurred in developed countries due to the relatively larger per capita reductions in red meat consumption and total energy intake.
- In the VGN scenario, food-related GHG emissions per capita were 4% lower in developed countries than in developing ones.
- 77 out of the 105 regions in the environmental analysis reduced their food-related GHG emissions per capita in the HGD scenario.
- The environmental benefits were greater for diets with fewer animal-sourced foods: for VGT and for VGN.
Limitations Noted in the Document
- The study acknowledges uncertainties in food demand and mortality projections.
- Possible deviations from the linear dose-response relationships linking risk factors and mortality.
- Inability to remove all possible confounding effects when deriving relative risk parameters.
- The study did not model the health consequences of changes in the consumption of all food groups.
- Uncertainties in the cost transfer method used for health valuation.
- The VSL approach is subject to the limitations of the value of statistical life estimates.
- The market responses associated with dietary changes, such as price changes, were not assessed.
Conclusion
The study underscores the crucial influence of dietary choices on both personal health and environmental well-being. Transitioning to diets with fewer animal-sourced foods and more plant-based options offers significant benefits, particularly in developing countries. The results indicate substantial reductions in global mortality and GHG emissions are achievable through dietary changes aligned with standard dietary guidelines. The economic valuation of health improvements demonstrates that these benefits could be comparable to, or even exceed, the value of environmental benefits. However, the practical implications of these findings highlight the need for significant changes in the global food system to align regional diets with the studied patterns. The study provides a comparative analysis of the health and climate change benefits of global dietary changes for all major world regions, projecting that health and climate change benefits will be greater the lower the fraction of animal-sourced foods in our diets. It acknowledges the complexities and uncertainties inherent in valuation methodologies, emphasizing that the use of these tools should encourage further research and policy actions to improve consumption patterns. The research encourages researchers and policy makers to improve consumption patterns through the identification of targeted, region-specific interventions across production and consumption to help achieve these benefits, as the transition towards plant-based diets could become a viable approach to improving both public health and environmental sustainability.
IFFS Team Summary
- Faunalytics Review: Weighing the Health and Climate Benefits of Eating Less Meat
- Transitioning to a more healthy plant based diet reduce global mortality by 6-10%
- It would decrease global GHG from food by 29-70% , compared to conventional diet
- The positive economic impact of reduced climate change for the future is also considered, and great economic variability exists in this complex domain
- Article was used as a reference for the 2017 Canada food guide process
- The largest absolute environmental and health benefits will be in developing countries
- Western high-income and middle-income countries gain most in per capita benefit
- Specifically compares Healthy Global Diet to Vegetarian and Vegan diets with respect to health and ecological impact
- Also identifies pulses as an ideal plant based protein source
- The Lancet Planetary Health
- https://www.thelancet.com/action/showPdf?pii=S2542-5196%2818%2930206-7
- https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(18)30206-7/fulltext?dgcid=raven_jbs_etoc_email
- Models at sustainable diets globally, in the context 150 low, middle and high income countries, and the relative ecological impact
- Uses a standard nutritional profile for incremental levels of meat reduction, health prevention, as well as semi veg, veg, and vegan diets
- i.e. each diet must attain certain level of calories, protein, and micronutrients
- Diets that were the most plant based, especially vegan achieved the most ecological benefits AND greatest health benefits
- “Flexitarians” reduce premature mortality by 19%, and vegans by 21% (the document actually mentions vegans)
- Plant based diets reduce
- GHG emissions by 54–87%
- nitrogen application by 23–25%
- phosphorus application by 18–21%
- cropland use by 8–11% (this statistic does not likely reflect a full switch to pulses)
- freshwater use by 2–11%
- (note that there is regional variation)
- these numbers reflect a shift towards plant foods, but not a full switch from animal protein to pulses
- In developing countries there is a decrease in resource use as more pulses are consumed, while meat is still consumed, but also an increase in resource use as more fruits and vegetables are added to a diet that is subsistence based.
- In developing countries, the environmental impact increases because net food consumption must increase to achieve nutritional targets
- levels of pulses, fruits and vegetables increase dramatically under plant based scenarios
- people in many developing countries have especially low levels of fruit and vegetable consumption,
- (much water is needed to increase)
- to quantify the diverse impact of animal foods in developing countries on biodiversity etc is beyond the scope of this study
- sustainable diets are more context specific and complex depending on local resources
- may involve low levels of animal protein and increased plant foods
- High income countries achieved the largest benefits with respect to health and environment, with incremental plant diet
- Study places emphasis on pulses as the main plant protein, and does specify vegan diets
- Calcium intake may be slightly lower on a vegan diet, and B12 may be absent.
- note that both are easily supplemented