Abstract
The food system is responsible for more than a quarter of all greenhouse gas emissions while unhealthy diets and high body weight are among the greatest contributors to premature mortality. Our study provides a comparative analysis of the health and climate change benefits of global dietary changes for all major world regions. We project that health and climate change benefits will both be greater the lower the fraction of animal-sourced foods in our diets. Three quarters of all benefits occur in developing countries although the per capita impacts of dietary change would be greatest in developed countries. The monetized value of health improvements could be comparable with, and possibly larger than, the environmental benefits of the avoided damages from climate change.
Generated Summary
This research couples a region-specific global health model with emissions accounting and economic valuation modules to quantify the health and environmental consequences of dietary changes. The study assesses the impact of shifting diets towards less meat and more plant-based foods across various world regions. The researchers employed a comparative risk assessment model to estimate age and region-specific mortality associated with dietary and weight-related risk factors. They also linked regional and scenario-specific food type consumption levels to greenhouse gas (GHG) emissions and placed a monetary value on changes in GHG emissions using the social cost of carbon. Additionally, the health consequences were monetized using the value of statistical life and projections of health-care expenditure. The study analyzes the health and climate change benefits of global dietary changes, emphasizing the potential of reduced meat consumption and increased consumption of fruits and vegetables, alongside an analysis of the economic value of these dietary shifts.
Key Findings & Statistics
- The food system is responsible for more than a quarter of all greenhouse gas emissions.
- Unhealthy diets and high body weight are among the greatest contributors to premature mortality.
- The study projects that health and climate change benefits will be greater the lower the fraction of animal-sourced foods in diets.
- Three quarters of all benefits occur in developing countries.
- 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 monetized value of the improvements in health would be comparable with, or exceed, the value of the environmental benefits.
- The economic benefits of improving diets are estimated to be 1-31 trillion US dollars, which is equivalent to 0.4-13% of global gross domestic product (GDP) in 2050.
- The HGD scenario would result in 5.1 million avoided deaths per year (95% CI, 4.8-5.5 million).
- Adoption of global dietary guidelines (HGD) would result in 79 million years of life saved (CI, 75-83 million).
- The vegetarian (VGT) diet would result in 7.3 million avoided deaths (CI, 7.0-7.6 million) and 114 million life years saved (CI, 111–118 million).
- The vegan (VGN) diet would result in 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% of avoided deaths were due to increased fruit and vegetable consumption.
- 19-30% of avoided deaths were due to a lower prevalence of being overweight and obese.
- About 45-47% of all avoided deaths were from reduced coronary heart disease (CHD).
- 26% of avoided deaths were from stroke.
- 16-18% of avoided deaths were from cancer.
- 10-12% of avoided deaths were from type 2 diabetes (T2DM).
- Compared with the reference scenario, the alternative diets require 15% less total energy intake.
- The HGD scenario increased fruit and vegetable consumption globally by 25% (99 g-d¯¹) and decreased red meat consumption by 56% (42 g·d¯¹).
- Food-related GHG emissions in the HGD scenario 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.
- The cost savings from dietary guidelines (HGD) will be 735 billion US dollars per year in 2050, with a range of $482–987 billion y¯¹.
- Vegetarian diets (VGT) could bring savings of $973 billion-y-1 (range $644-1,303 billion y¯¹).
- Vegan diets (VGN) could bring savings of $1,067 billion-y¯¹, (range $708-1,426 billion-y¯¹).
- The value-of-statistical-life approach showed that the monetized value associated with diet-related changes in mortality is $21 trillion-y¯¹ in 2050, with a range of $10-31 trillion y¯¹.
- For VGT, the value is $28 trillion-y¯¹ ($14–42 trillion-y¯¹), and for VGN, $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.
- The monetized environmental benefits of HGD diets is $234 billion y¯¹, with values in the range $89-729 billion-y-¹ for different assumptions about discount rates.
- For VGT diets, benefits are $511 billion-y-1 ($194-1,589 billion-y¯¹).
- For VGN diets, benefits are $570 billion y¯¹ ($217–1,773 billion y¯¹).
Other Important Findings
- The greatest absolute environmental and health benefits result from diet shifts in developing countries, although Western high-income and middle-income countries gain most in per capita terms.
- The health consequences of adopting these diets have not been explicitly modeled or quantitatively analyzed.
- The study uses a region-specific global health model to link the health and environmental consequences of changing diets.
- The reduced mortality in the VGT and VGN scenarios compared with the HGD scenario was due to lower red meat consumption and higher fruit and vegetable consumption.
- The nonmeat diets require greater increases in the consumption of fruits and vegetables and of pulses.
- About three-quarters of the total GHG reductions occurred in developing countries, in particular in East Asia and Latin America.
- Food-related GHG emissions per capita fell twice as much in developed compared with developing countries across all three nonreference scenarios.
- The average per capita GHG emissions from someone in a developing country was 53% that of a person from a developed country in the REF scenario but only 26% and 20% in the HGD and VGT scenarios, respectively.
- The regional distribution of the monetized economic benefits broadly corresponds to the distribution of changes in mortality despite regional variation in the value of statistical life.
Limitations Noted in the Document
- The estimates are not exactly comparable, nor do they include all consequences of dietary changes.
- The economic valuation is considered a first step, and the exact valuation method used considerably affects the estimated amounts.
- The health consequences of changes in the consumption of all food groups were not able to be modeled.
- The study did not account for the beneficial impacts of dietary change on land use through avoided deforestation.
- The study did not take into account emissions feedbacks from increased life expectancy in the dietary-change scenarios.
- Uncertainties include food demand and mortality projections, possible deviations from the linear dose-response relationships linking risk factors and mortality, and the inability to remove all possible confounding effects.
- The valuation techniques used are subject to significant uncertainties, including the discount rate and the benefit transfer method used to obtain region-specific costs-of-illness (Col) and value-of-statistical-life (VSL) estimates.
- The study did not assess the market responses associated with dietary changes (e.g., due price changes).
Conclusion
The analysis reveals substantial benefits from dietary changes towards plant-based foods, with significant reductions in diet-related mortality and greenhouse gas emissions. The study emphasizes the crucial role of modifying the consumption of red meat, fruits, and vegetables, and altering total energy intake, which could result in a significant decrease in overall mortality. The research suggests that these dietary shifts could lead to major health benefits, particularly in developing countries. However, the study acknowledges limitations, such as not modeling the health consequences of changes in all food groups and uncertainties in the economic valuation methods used. Despite these caveats, the projected benefits are substantial enough to encourage researchers and policymakers to improve consumption patterns. The analysis underscores that the greatest benefits of dietary changes will be in developing countries, highlighting the importance of targeted interventions in these regions. The study’s findings are consistent with previous research, indicating the potential of dietary changes to mitigate food-related GHG emissions. Overall, this research highlights the interconnectedness of food systems, health, and the environment, emphasizing the need for changes in dietary patterns to benefit both human health and the planet. The economic valuation of health benefits, which is comparable to, or surpasses the value of environmental gains, underscores the financial advantages of healthier eating habits. The study concludes that the global food system requires significant changes to realize these benefits, and this is what the research aims to accomplish with its findings and suggestions.
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