The Role of Healthy Diets in Environmentally Sustainable Food Systems

Clark M, Macdiarmid J, Jones AD, Ranganathan J, Herrero M, Fanzo J. The Role of Healthy Diets in Environmentally Sustainable Food Systems. Food and Nutrition Bulletin. 2020;41(2_suppl):31S-58S. 

Relevant to: 

All Dietitians-Nutritionists interested in shifting the population toward healthier and sustainable diets. 

Question: 

This paper compiles existing research to provide an ambitious review of four questions: i) how projections of global diet transitions translates into an increasing impact on human and environmental health; ii) how transitions to healthier diets can advance environmental targets; iii) how shifting to healthy diets might contribute to sustainable food systems in four dissimilar countries (using case studies); iv) steps that governments and business can take to advance sustainable and healthy diets.  

Bottom line for nutrition practice: 

Across the globe, dietary transitions and projected population increases mean that environmental impacts resulting from diet are expected to grow quickly; accompanying dietary changes will also likely have a negative impact on human health. Consuming win-win diets (beneficial to health and the environment) (i.e., Mediterranean, low-meat/flexitarian, pescatarian, or vegetarian diet), and “win-win” foods (e.g., whole grain cereals, fruits and vegetables, legumes, and most nuts and seeds) are necessary to shift diets to be healthier and more sustainable. The authors also note that it is important to avoid unintended consequences by identifying “win-lose” (positive for health but with high environmental impacts – e.g., fish) or “lose-win” (harmful to health but with low environmental impact, e.g., sugar and some oils). Red and processed meat are recognized as lose-loses. 

Case studies from different countries show that approaches to shift population diets need to be unique to the context of each country, and require simultaneous action by the public and private sectors and governments.  The authors offer recommendations that governments can take to shift the diets of their population to be healthier and more sustainable: i) calculate the economic argument for the need to shift diets; ii) set measurable targets for transitioning diets; iii) trial a range of interventions such as restricting or promoting access (e.g., zoning); fiscal measures (e.g., taxes); trade rules (e.g., subsidies); public procurement; persuasion/ campaigns; information (e.g., labelling); research and development; iv. ensure coherence between agriculture, health, water, and environmental policies.  

Finally, the authors highlight the Shift Wheel framework by Ranganathan et al., which outlines four proven marketing approaches that businesses can use to encourage consumers to move to more sustainable diets: i. reduce disruption to existing habits; ii. sell a compelling benefit to consumers (e.g., health or affordability). iii. maximize awareness (e.g., advertising; availability and display); iv. evolve social norms (e.g., efforts to make sustainable food more socially desirable). See: “Of Additional Interest” for more information.  

Abstract:

Background: 
The global food system is directly linked to international health and sustainability targets, such as the United Nation’s Sustainable Development Goals, Paris Agreement climate change targets, and the Aichi Biodiversity Targets. These targets are already threatened by current dietary patterns and will be further threatened by 2050 because of a growing population and transitions toward diets with more calories, animal-source foods, and ultra-processed foods. While dietary changes to healthier and predominantly plant-based diets will be integral to meeting environmental targets, economic, social, and cultural barriers make such dietary transitions difficult. 

Objective: 

To discuss the role of healthy diets in sustainable food systems and to highlight potential difficulties and solutions of transitioning toward healthier dietary patterns. To do so, we synthesize global knowledge and conduct a series of case studies on 4 countries that differ in their social, economic, political, and dietary contexts: Brazil, Vietnam, Kenya, and Sweden. 

Conclusions: 

No single “silver bullet” policy solution exists to shift food choices toward sustainable healthy diets. Instead, simultaneous action by the public sector, private sector, and governments will be needed. 

Details of results: 

Details are outlined under the four questions posed by the authors.  
i) How projections of global diet transitions will increasingly impact human and environmental health Across the globe, dietary transitions and projected population increases mean that between 2010 -2050, the “average total per capita caloric supply is projected to increase 15%, while supply of meat is projected to increase >25%, supply of dairy and eggs >50%, and supply of calories from oils, alcohol, and sugar >60%” (p.S33). Increased food production will come with concurrent environmental impacts. Dietary changes will also likely increase diet-related disease and mortality risk, due to overconsumption and consequent weight gain, an increased consumption of foods high in sodium, and low intakes of whole grains, fruits and vegetables. These health concerns are projected to increase most quickly in lower middle and upper middle countries. 

ii) How transitions to healthier diets can advance environmental targets 
Transitions can be advanced by the consumption of “win-win” diets (beneficial to health and the environment) (i.e., Mediterranean, low-meat/flexitarian, pescatarian, or vegetarian diet). Focusing on “win-win” foods (e.g., whole grain cereals, fruits and vegetables, legumes, and most nuts and seeds) is also important in shifting diets to be healthier and more sustainable. The authors also note that it is important to avoid unintended consequences by identifying “win-lose” (positive for health but with high environmental impacts – e.g., fish, and nuts (the latter in relation to water use) or “lose-win” (harmful to health but with low environmental impacts), such as sugar and some oils. If sugar and oil production result in land use change, as frequently seen in the tropics, it is more likely that these foods are “lose-lose”. Red and processed meat are recognized as “lose-lose”. See Figure 4 for the impacts of various foods on health and the environment. On the other hand, in low-income contexts, increased consumption of meat, fish, dairy, and eggs may be beneficial if undernutrition occurs in nutrients such as iron and zinc. 

iii)  Shifting to healthy diets and sustainable food systems: case studies from four countries 
The authors delineate in detail how the countries of Brazil, Kenya, Vietnam, and Sweden differ in relation to recent dietary changes, related health and environmental impacts, and possibilities for transitioning to healthier and more environmentally sustainable diets. Issues such as food cultures, dietary preferences, institutional structures, economic costs and barriers are unique to each country. Thus, interventions must be specific to each country, and trade-offs need to be balanced and monitored. In Brazil, the authors highlight the need to align agricultural, health and environmental policies in order to address increasing ill health and their environmentally unsustainable food system – deforestation and biodiversity loss are particular problems. Vietnam has abundant natural resources and has reduced rates of undernutrition; the authors suggest that increasing fish consumption in place of animal source foods and ensuring the fish is from sustainable aquaculture systems and investments in fisheries will help to transition Vietnam toward more sustainable and healthy diets. In order to improve food and economic security in Kenya, the authors highlight the need for increasing crop and livestock yields through improved management and access to agricultural inputs — in part as a way to reduce land use change and habitat conversion for food production.  

The authors illustrate Sweden as an example of a high-income country that is experiencing ill health as a result of overconsumption of some less healthy foods, and underconsumption of healthier foods. They focus on Sweden’s role in helping to develop the “New Nordic Diet” – which integrates nutrition and environmental sustainability principles (note that Sweden, like Brazil, has also incorporated integrated sustainability principles into their national dietary guidelines). However, the authors argue that the New Nordic Diet needs to be more ambitious in order to improve environmental sustainability, requiring larger reductions in meat, dairy and eggs, improvements in farming practices and food loss and waste reductions. 

Looking to the global food system, the authors propose changes such as the reduction of food loss and waste, technological adaptation, and changes in food formulation, processing, and preparation.  

iv) How governments and business can advance sustainable and healthy diets 
The authors note that governments, business, and civil society need to work together to advance large-scale dietary shifts, and also suggest that interventions need to move beyond the frequently used method of information distribution (e.g., food package labelling, campaigns). As food choices are driven by many interrelated factors (e.g., price, age, gender, culture, geography, access, marketing), the authors suggest that investment occurs to understand consumer motivation. This will allow for the design of an appropriate array of complementary interventions such as: restricting or promoting access (e.g., zoning); fiscal measures (e.g., taxes); trade rules (e.g., subsidies); public procurement; persuasion/ campaigns; information; research and development. Given the limited experience and evidence supporting interventions to shift diets, they recommend taking an experimental approach to interventions, including developing baselines of current diets, setting targets, and monitoring outcomes. They also advise that governments: assess the economic case for the need to shift diets; set measurable targets for transitioning diets; and ensure coherence between agriculture, health, water, and environmental policies (see S49 for more information on interventions).  
The authors recommend similar approaches for business. They suggest setting measurable targets (e.g., increasing sales of plant-based foods, or reducing environmental impacts); experimenting with interventions to shift consumer choice (e.g., behavioural or marketing techniques, both of which they have much experience in); collaborate with government and civil society. They also highlight the Shift Wheel framework by Ranganathan et al. (2016), which outlines four approaches that businesses can use – based on proven private sector marketing tactics — to encourage consumers to move to more sustainable diets: i. reduce disruption to existing habits; ii. sell a compelling benefit to consumers, such as health or affordability. iii. maximize awareness (e.g., advertising; availability and display); iv. evolve social norms (e.g., efforts to make sustainable food more socially desirable or to lower the desirability of less sustainable food). See p.S49 for the framework, or “of additional interest” for the original source of this work.  

Of additional interest: 

The Shift Wheel framework outlining complementary approaches for business to advance sustainable diets is outlined in further detail in:  
Ranganathan J, Vennard D, Waite R, Dumas P, Lipinski B, Searchinger T. Shifting diets for a sustainable future. Creat a Sustain Food Fut. 2016;11(4):90. doi:10.2499/9780896295827_08  
https://icdasustainability.org/report/world-resources-report-creating-a-sustainable-food-future-2/  

Editor’s comment:  

Of interest – the authors note that the environmental impact between foods is similar across the different nutritional units (e.g., per calorie or per gram). This addresses a frequent critique of environmental impact measures from proponents of animal-based foods, who sometimes argue that animal based foods provide more calories than plant based foods when analyzed by weight of food. The authors stress that even though the mean environmental impact of a given food can vary, the lowest impact animal-source food usually has higher environmental impacts than the highest impact plant-based food. 

Open access link to article: 

https://journals.sagepub.com/doi/full/10.1177/0379572120953734 

Conflict of interest/ Funding:  

No conflict of interest was declared by the authors; funding was received from the FAO.  

External relevant links:

N/A

Corresponding author: 

michael.clark@npdh.ox.ac.uk 

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