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Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop (2019)

Chapter:2 What Are Sustainable Diets?

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Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
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2

What Are Sustainable Diets?

In the first session, moderated by Fergus Clydesdale, University of Massachusetts Amherst, speakers explored the complexities and necessary compromises of sustainable diets. This chapter summarizes the Session 1 presentations and the discussion that followed. Highlights of the presentations are provided in Box 2-1.

THE DIMENSIONS OF SUSTAINABILITY

Setting the stage for presentations to follow, Adam Drewnowski, University of Washington, Seattle, emphasized the multiple dimensions and interdisciplinary nature of sustainability. He called attention to two documents. He first described the 2005 Giessen declaration, which articulated the concepts of personal, population, and planetary health. He remarked that this was the first time he had seen mention of “personal, population, and planetary health” in a nutrition journal. The declaration, which, he asserted, should have received a wider audience, stated that the new nutrition science ought to encompass social, economic, and environmental as well as biological dimensions, and that the study of integrated food systems should serve as the basis for food and nutrition policies (Beauman et al., 2005). The document was signed by a number of prominent nutrition experts, he added, with the intent of embracing other sciences and clearing the way for a more interdisciplinary approach to nutrition. Drewnowski then called attention to the 2012 Food and Agriculture Organization (FAO) report Sustainable Diets and Biodiversity (FAO, 2012b). It was from this report

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×
Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

that he, as well as several other workshop speakers, drew their definition of sustainable diets (see Box 2-2).

The Four Dimensions of Sustainability: Tensions and Contradictions, Trade-Offs, and Compromises

According to Drewnowski, the FAO definition of sustainable diets has four dimensions: (1) nutrition and health, (2) economic, (3) social and cultural, and (4) environmental. He emphasized that sustainable diets not only have low environmental impact but also are healthy, affordable, and acceptable to society. In his experience, when people talk about sustainable diets, they are often talking only about the impact of diets on the environment, and he stressed the importance of including all four dimensions in such discussions. “Diets are not healthy and sustainable,” he said. “They are sustainable only if they are healthy to begin with.” In addition, though often missing from the discussion, are the economic and social dimensions.

Drewnowski went on to assert that the dimensions of sustainability lead to inherent tensions and contradictions. For example, he elaborated, some energy-dense foods cost less per calorie and may have a lower impact on the environment relative to other, more nutritious foods, but also have low nutrient density. An extreme case is sugar. “If you want a plant food with the lowest land cost, lowest water use, and lowest greenhouse gas emissions,” Drewnowski observed, “look no further than sugar.”

Drewnowski explained that the trade-offs and compromises necessitated by these inherent tensions and contradictions call for a focus on food systems rather than individual foods. He added that all of the various connections along the food system path lead from production to consumption to waste and disposal (Downs et al., 2017; FAO, 2012b; Johnston et al., 2014). He emphasized that optimization of all of the different considerations

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

that arise is context dependent as the trade-offs are not necessarily the same for all countries or regions, or even for all neighborhoods.

According to Drewnowski, modeling sustainable food systems and predicting and optimizing all of the various considerations involved requires gathering and integrating data from multiple sources, both private and public. He remarked that one of the intents of this workshop was to bring together experts familiar with these types of models and data sources. He noted, too, that this modeling is a two-way street: existing diets can affect the climate, which in turn can affect future diets. Because diets can be either the cause or the outcome, he observed, “to some extent, existing diets are paving the way for future diets.”

The Metrics of Sustainable Diets

Drewnowski went on to explain that each of the four dimensions, or domains, of sustainable diets relies on a different set of measures and metrics. He then described some of these metrics.

Nutrition Domain

When assessing nutrition, two key measures Drewnowski uses in his own work are energy density (dietary energy per unit weight) and nutrient density (nutrients per reference amount). He remarked that the concept of nutrient density can be complex, and different ways of measuring the nutrient density of foods (e.g., using nutrients per calories or nutrients per unit weight for nutrient profiling) have been the subject of recent discussions. He explained that nutrient profiling is a technique for rating individual foods based on their nutrient content or ratio of nutrients to calories. Without going into detail, he mentioned the European Food Safety Authority (EFSA) guidelines for nutrient profiling and noted a current trend toward what he termed “hybrid nutrient profiling,” whereby not just nutrients but also healthy food ingredients can contribute to an overall nutrient density score (Drewnowski and Fulgoni, 2008). In his opinion, measuring nutrient density in terms of nutrients per 100 kilocalories (kcal) is arguably more useful than measuring nutrients per 100 grams (g) or per serving. The former approach, he elaborated, allows for direct comparisons of affordability, generally measured as calories, or nutrients per unit cost. He added that measuring cost per calories makes it possible to see, for example, that energy-dense foods (fats, sugars, and grains) often have lower nutrient densities compared with vegetables and fruit (see Figure 2-1). He noted that energy-dense sweets and fats tend to cost less per calorie and may have a lower environmental footprint, but they also tend to be nutrient-poor. He noted that not only have energy-dense foods become dominant in the food

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×
Image
FIGURE 2-1 The relationship between nutrient-rich foods and energy density.
NOTES: NRF = nutrient-rich food. The y-axis depicts energy density as kilocalories (kcal) per 100 grams; the x-axis depicts nutrient-rich foods by NRF 9.3, which is a European Food Safety Authority nutrient profiling score.
SOURCES: Presented by Adam Drewnowski on August 1, 2018, from Drewnowski, 2017.

supply, but research suggests that high energy density promotes overeating and leads to overweight.

Drewnowski also pointed out that many energy-dense foods are plant foods. “We actually overconsume plant foods,” he said, which include vegetable oils, sugars, and high-fructose corn syrup, adding that less energy-dense plant foods may be more satiating at fewer calories, but are also considerably more expensive in terms of per calorie monetary cost.

Economic Domain

Drewnowski went on to observe that the finding that nutrient-dense foods typically cost more (see Figure 2-2) has been noted not just in the United States, but also in France and Mexico. He suspects that the same is true in low- and middle-income countries as well.

Environmental Domain

According to Drewnowski, more nutrient-dense foods and more nutrient-dense diets also typically entail higher carbon costs. He remarked

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×
Image
FIGURE 2-2 Relationship between monetary cost (“energy cost,” or dollars per 1,000 kilocalories [kcal]) and nutrient density (NRF 9.3 per 100 kcal).
NOTES: NRF = nutrient-rich food. The y-axis depicts nutrient density by NRF 9.3, which is a European Food Safety Authority nutrient profiling score; the x-axis depicts energy cost as U.S. dollars per 1,000 kcal.
SOURCES: Presented by Adam Drewnowski on August 1, 2018, from Drewnowski, 2017.

that carbon cost is often calculated per 100 g or per kilogram of food with little attention to what the food actually is, and stated that he prefers to measure carbon cost from the standpoint of calories. Given that an individual needs 2,000 calories or a certain amount of protein per day, for example, one can then ask about the environmental cost of producing those calories or grams of protein. In Drewnowski’s opinion, weight is entirely immaterial when one is comparing emissions of greenhouse gases (GHGs), given that some foods are mostly water (e.g., there is actually more water per gram in spinach than in a carbonated soft drink). In contrast, he continued, comparing GHG emissions based on calories reveals a direct linear relationship between the nutrient density of foods and their carbon costs per 100 kcal (see Figure 2-3). “Nutrient-rich foods actually are more costly from the standpoint of energy than are candy and sugar,” he pointed out, adding that there is also a linear relationship between total dietary calories and GHG emissions. “The more calories people eat,” he said, “the more carbon energy the diets consume.”

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×
Image
FIGURE 2-3 The linear relationship between nutrient density and carbon cost.
NOTES: CO2 = carbon dioxide; NRF = nutrient-rich food; RTE = ready-to-eat; SSB = sugar-sweetened beverage. The y-axis depicts carbon cost as CO2 per 100 kilocalories (kcal); the x-axis depicts nutrient density by NRF 9.3, which is a European Food Safety Authority nutrient profiling score.
SOURCE: Presented by Adam Drewnowski on August 1, 2018.

Social Domain

In the social domain, Drewnowski called for measuring food patterns rather than individual foods or nutrients when assessing the relationship between diet and health outcomes, especially obesity. Food patterns are determined by society more so than the consumption of individual nutrients or foods, he asserted. Yet, he observed, studies in nutrition epidemiology typically link individual nutrients, foods, or dietary ingredients with health outcomes while failing to adjust for socioeconomic status, past history, culture, and other contextual factors. To illustrate this point, he described how in Seattle, a map of the consumption of soda by neighborhood showing that people living in less expensive houses near freeways consume more soda relative to people living in mansions on the waterfront costing several million dollars can be overlaid on a map of the distribution of obesity by neighborhood. The comparison reveals more obesity near the freeway than on the waterfront. Thus, Drewnowski argued, improving the healthy eating

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

index among people living in neighborhoods near the freeway “is not simply a question of getting people to switch from one food to another … it is all about geography, education, income, and food patterns.”

Final Remarks

Ending on what he termed a provocative note, Drewnowski suggested that researchers studying obesity replace their focus on individual dietary components with a focus on food patterns. He pointed to different studies on obesity, both by the same researchers and both published in the same journal but several years apart, with one implicating dietary fat (Bray and Popkin, 1998) and the other high-fructose corn syrup (Bray et al., 2004). “I think that we need a paradigm shift,” he argued.

In closing, Drewnowski called for multiple types of input data, assessments of the costs and benefits of alternative diets, estimates of likely regional compromises and trade-offs, and models that are sensitive to prices and social concerns. Finally, he emphasized the collective nature of the endeavor to achieve sustainable diets and urged the engagement of academia, governments, nongovernmental organizations (NGOs), and the food industry.

IMPLICATIONS AND RELEVANCE OF SUSTAINABLE DIETS INTERNATIONALLY: IT’S ALL ABOUT THE CONTEXT

Building on Drewnowski’s presentation while also placing evidence on sustainable diets in a political context, Jessica Fanzo, Johns Hopkins University, Baltimore, Maryland, began by talking briefly about what she described as the “long, tangled history” of discussions around sustainable diets. Today, she noted, sustainable diets are being discussed in global reports, such as the 2016 report of the Global Panel on Agriculture and Food Systems for Nutrition, Food Systems and Diets: Facing the Challenges of the 21st Century (GLOPAN, 2016); the Global Nutrition Report 2017 (Development Initiatives, 2017); and the 2017 report of the Committee on World Food Security, Nutrition and Food Systems (HLPE, 2017). But, she observed, the topic is not new: “It comes in and out of fashion,” she said. She mentioned Joan Dye Gussow’s work on ecological nutrition in the 1970s and Gussow’s book Chicken Little, Tomato Sauce, and Agriculture: Who Will Produce Tomorrow’s Food? (Gussow, 1991). She agreed with Drewnowski, however, that past discussions centered mainly on the environment and human health, with little consideration of economic, sociocultural, and other factors that are recognized today as being so important to sustainable diets.

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

Turning the Food and Agriculture Organization (FAO) Definition of Sustainable Diets into a Feasible Reality

Fanzo characterized the goal of turning the 2012 FAO definition of sustainable diets (see Box 2-2) into a feasible reality as a “real challenge,” particularly for those living in low- and middle-income countries and in contexts where tremendous inequalities force policy makers to make difficult decisions about trade-offs. Consumers, too, must navigate sustainable diets, she added. Currently, she observed, it is difficult to understand what foods are and are not sustainable, and what to believe and not believe about what is written about food and diets in the media. She added that consumers also must consider taste, preference, convenience, practicality, and affordability to fulfill their own demands and desires. The private sector, in turn, must answer to those demands while ensuring that there is a market for its products and that consumers have economic incentives to buy them. In sum, Fanzo said, many stakeholders must be considered when determining how to turn the definition of sustainable diets into a reality.

Sustainable Diets in Low- Versus Middle-Versus High-Income Countries

Fanzo went on to state that in some low-income contexts, where populations cannot necessarily afford animal-sourced foods, many of the diets consumed are plant-based and could be considered quite sustainable in the way they are grown and processed. She pointed to a working paper by the World Resources Institute showing global differences in daily protein consumption (based on supply chain data). According to that paper, daily per capita protein consumption is lowest in India and highest in Brazil, followed by the United States and Canada (Ranganathan et al., 2016). As urbanization and economic growth progress, Fanzo observed, meat consumption is rising, with some exceptions.

The question then arises of whether the plant-based diets consumed in many low-income contexts are sustainable, Fanzo continued, and whether they are fulfilling the nutritional needs of those communities. Animal-sourced foods are important for growth, she noted, particularly for young children. She characterized as controversial the conclusion in a recently published paper in Lancet Global Health that in sub-Saharan Africa, particularly in west Africa, people are eating among the healthiest diets in the world (Imamura et al., 2015), given that malnutrition burdens (stunting, micronutrient deficiencies) remain high in that region. She added that, based on an analysis of 2016 UNICEF global data, children aged 6 to 23 months worldwide are eating one type of animal-sourced food per day or none at all. In many places, she reported, even if young children are eating a

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

diet diverse in plant-based foods, with many legumes and leafy greens, they still lack access to enough iron and zinc in their diet, as illustrated by data from Bangladesh, Ethiopia, and Vietnam (Dewey and Vitta, 2013). Iron and zinc, she emphasized, are critical micronutrients for cognition and growth.

Regarding climate change, Fanzo observed, an additional challenge for low-income countries is that they are affected by the dietary decisions of those living in higher-income countries. “Our choices about what we consume will impact those people who have the inability to adapt and deal with climate change,” she said. “Our choices matter.”

Global Transitions and Transformations: The Growing Demand for Meat

Expanding on the observations summarized above, Fanzo explained that the world is undergoing rapid demographic, epidemiologic, and nutrition transitions: urbanization is expanding, with people moving from rural, subsistence-agriculture landscapes into urban centers; people have more disposable income; physical activity is changing; the food system is becoming increasingly global; and health outcomes also are changing, as seen in rising rates of obesity and diet-related noncommunicable diseases. Although approximately 1 billion people go to bed hungry every night, while another billion are purposely exercising and consuming a healthy diet, most of the world—about 5 billion people—is in a state of rapid transition, including rapid shifts in diet (Crino et al., 2015; Drewnowski and Popkin, 2009; Fanzo et al., 2017). Fanzo herself spends a great deal of time in Myanmar, where, she said, the “hippest” restaurant at present is KFC. Why? “It taps into desire,” she explained, recalling queues five blocks long to get into a KFC in Yangon. Of this growing demand for meat, she said, “I cannot emphasize that enough,” adding that it is not just the demand for meat that is growing worldwide (see Figure 2-4), but also the demand for animal feed. “This whole system needs to be rethought,” she argued, stating that those 5 billion people are less able to access what would be considered a healthy, sustainable diet today than they were in the past.

Disjointed Policies and Policy Trade-Offs

Dietary guidelines are almost always a mismatch with what agricultural systems and the food supply can bear, Fanzo continued, because food-based dietary guidelines are often developed without the involvement of agronomists and environmental scientists. To illustrate this point, she cited work by Steven Wiggins at the Overseas Development Institute (ODI) who has demonstrated that if everyone followed the U.S. Dietary Guidelines for Americans (DGA), the world’s dairy supply would be outstripped (Wiggins and Keats, 2014). Other research has shown that agriculture systems are

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×
Image
FIGURE 2-4 The growing demand for meat: (a) daily animal-based protein availability per capita (i.e., based on supply chain data), 1961–2050; (b) examples of the movement of meat globally.
SOURCES: Presented by Jessica Fanzo on August 1, 2018, modified from Ranganathan et al., 2016.
Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

becoming more homogeneous, she added, with fewer crop species responding to a growing demand (Khoury et al., 2014). Again, she urged greater thought as to what agriculture can deliver toward the achievement of nutritional goals. She stressed that policy makers are constantly dealing with these trade-offs, citing environmental, health, and economic trade-offs involved with such commodities as palm oil, olive oil, and grassfed beef, to name a few.

Trade policies play a part as well, Fanzo continued. She and her colleagues, for example, recently published a study showing an increase in the number of people with micronutrient deficiencies in the absence of trade (Wood et al., 2018). “There are always these trade-offs that we have to consider,” she reiterated.

Evidence Gaps

Fanzo agreed with Drewnowski that there are clear gaps in scientists’ understanding of what constitutes a sustainable diet for different populations and how sustainable diets in different contexts are best measured. More specifically, she called for better characterization of the key determinants of a sustainable diet and how these determinants can be measured in a spatiotemporal way, using a suite of indicators such as those described by Drewnowski. In addition, she called for guidance on what a sustainable diet would mean economically for all actors in the food value chain, particularly in low- and middle-income countries. For example, if industry is being asked to become more sustainable, what does that mean for this sector economically?

Finally, Fanzo called for policy analysis to better integrate sustainability issues into policies relevant to diets and nutrition and to create what she described as “policy coherence.” She mentioned a recent study in which she and her colleagues examined a suite of indicators and then plotted them on different countries to create “dashboards” (Gustafson et al., 2016). But, she asked, would a policy maker sitting at his desk in Senegal and looking at this dashboard diagram know what to do with it? “Probably not,” she said, acknowledging that she was critiquing her own work, and explaining that policy makers are thinking more about value chains and how to “get food from A to B to C” (Fanzo et al., 2017). The question for them, she elaborated, is how to inject sustainability into a value chain. Thus, instead of handing policy makers a suite of indicators or a dashboard and telling them to look at the data, she stressed, “we need to start thinking like policy makers and understanding what they need to make an informed, evidencebased decision.”

In another recent study, Fanzo and colleagues examined three different national strategies in Nepal: the Multi-Sectoral Nutrition Plan, the National

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

Biodiversity Strategy and Action Plan, and the Agriculture Development Strategy. They systematically examined whether the three strategies captured elements of sustainability across a range of themes, including environmental, sociocultural, economic, and nutritional. Their results showed that the Agriculture Development Strategy included the most sustainability elements, and the Multi-Sectoral Nutrition Plan the least (Downs et al., 2017). “What does this say?” Fanzo asked. “We need to get the global nutrition community thinking about sustainability,” she suggested. Agriculture thinks about it more, she said, because it is their “bread and butter.”

Coming to Grips with Evidence-Based Policy Realities

While the hope is that all policy making is rooted in solid evidence, Fanzo continued, in reality there is no policy-making cycle in which to inject evidence at the point of decision making (Pew-MacArthur Results First Initiative, 2014; Sutcliffe and Court, 2005; Young and Quinn, 2002). The policy-making cycle typically involves an assessment, then a budget, then implementation, followed by monitoring and readjustment, she elaborated, describing policy making as a messy, unpredictable, complex process. Evidence may resonate, or it may not, she explained. When policy makers are making decisions, she observed, they do look at evidence, but they also use judgment; gather information from lobbying groups; and consider their country’s habits, traditions, and values. Thus, while evidence-based policy may be improving, policy is still also opinion based (Davies, 2004; Sutcliffe and Court, 2005). For researchers who work with evidence, Fanzo suggested, this can be a difficult reality to grasp. So while she agreed with Drewnowski that more evidence is needed, she believes researchers need to start thinking about what to do with that evidence. Policy makers do not read Nature or The Lancet, she observed, nor is writing a policy brief enough, in her experience. She spoke of the “bounded realities” within which policy makers are operating and their need to make quick decisions with limited information. In sum, she asserted, “we need to reject romantic notions that policy makers think like us, as scientists, and that there is an identified point of decision at which experts can contribute to the evidence that makes an impact.”

In Fanzo’s opinion, given how the world has rallied around the Sustainable Development Goals (SDGs), now is an opportune time to reinvigorate the dialogue on sustainable diets. She mentioned that all United Nations (UN) Member States would be meeting in 2019 to report on where they are with respect to the SDGs and identified that meeting as an important venue for examining what has been achieved in the area of sustainable diets.

In closing, Fanzo cited an article that had just been published that morning (August 1, 2018) in The New York Times about how the science

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

around climate change was clear enough three decades ago that it could be laid out well for policy makers, along with solutions for how to address it (Rich, 2018). But then, she said, concern about climate change went out of fashion. Now, she asserted, it is back in fashion. “This is my call to all of you,” she stated, “that maybe we know enough. There has been a lot published on sustainable diets. We need to be thinking about ensuring that this kind of thing does not happen again, where we knew what to do 30 years ago, and policy makers just did not act on it.” She ended by saying, “Be thinking policy.”

DECISION MAKING UNDER UNCERTAINTY: SUSTAINABLE DIETS FOR CONDITIONS OF SCARCITY OR ABUNDANCE

Parke Wilde, Tufts University, Boston, Massachusetts, began by asserting that the inherently multisectoral nature of sustainable diets requires engaging, in the same forum, people thinking about public health and nutrition, about the environment and climate change, about food consumers, about supply chains and food waste, about farmers and food producers, and about reducing poverty (FAO, 2012b; Johnston et al., 2014). These people are not thinking the same thoughts, he observed, nor do they share the same goals. Controversy ensues, he explained, whether the topic is dietary guidelines, food labeling, carbon taxes, farm subsidies, genetically modified organisms (GMOs), agricultural conservation programs, water allocation, or something else. Thus, he argued, sustainable diets are contentious, and the question then is how these sectors can talk to each other.

Wilde offered several suggestions for communication among the various sectors, beginning with workshops such as this and documents such as Sustainable Diets and Biodiversity (FAO, 2012b) and the recently released Sustainable Diets (Mason and Lang, 2017). Eco-labels and other food labels are another forum for communication, he added, explaining that food labels not only reach greater numbers of people relative to workshops and documents, but also are valuable for linking information across different stages of the food marketing chain. But, he noted, labels have shortcomings based on a complexity that requires considering a number of different factors to ensure that consumers can make use of the labels. As another forum for communication, Wilde cited the production standard checklists (e.g., standards for safety or ecology) that are negotiated between agricultural producers and input suppliers on the one hand and food retailers, buyers, or the intermediaries who represent them on the other. Although less visible than labels to the public, these checklists are contentious, highly negotiated documents specifying what the standards of production should be.

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

Food Prices as a Forum for Communication

Wilde then turned to a final forum for cross-sector communication—prices. It is widely thought that prices are too thin a signal to be useful for this purpose, he remarked. However, he observed, economists think of them as highly robust signals of what is going on in different parts of the economy. He likened food prices to the aperture on a camera: it seems like a small hole, but in fact, a great deal of information passes through it. He asserted that food prices reveal much information about sustainable diets, such as what the demand is for different products under different conditions and what revenue farm owners and operators receive, how much farm laborers earn, how much healthy food costs for consumers, and what the big picture looks like with respect to scarcity and abundance. For the remainder of his talk, Wilde focused on the latter.

More specifically, Wilde described as the thesis of his talk that “conversations about sustainable diets play out differently in low-priced environments [abundance] and in high-priced environments [scarcity]. We need to be braced for both.” For example, when food prices are low, conversations and public policy making around land conservation, such as whether to hold land aside from agricultural production, are easier to conduct than is the case in a high-priced food environment. As examples of such conversations, Wilde cited decisions that need to be made with respect to the U.S. Department of Agriculture’s (USDA’s) Conservation Reserve Program or, in Malaysia, about palm oil, mentioned earlier by Fanzo. On the other hand, he observed, some conversations are easier when food prices are high, including conversations about livelihoods for farmers, economic incentives to reduce food waste, and investments in alternatives to traditional meat products.

The Economics of Sustainable Diets: How Cost Is Passed Down the Market Chain

Wilde argued that if economics are part of a sustainable diet, with all stakeholders earning a reasonable livelihood, it is essential to understand how cost can be passed down the marketing chain. A photograph that he took of a Coalition of Immokalee Workers (CIW) rally for better wages in March 2018 showed dozens of protestors on a street, all wearing coats; some wearing winter caps; and many holding signs, including two people holding a banner reading “Fighting for Fair Food! Luchando por Comida Justa!” The question, he said, is not why these people are rallying for better wages or a better piece rate on the tomatoes they harvest—“That stands to reason,” he said—but why they are wearing winter coats and why they are rallying in New York City in March rather than in Florida. The answer, he

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

said, is prices. He explained that tomato growers in Florida are in a competitive business in which they can claim, with complete credibility, that it is very difficult for them to agree to higher wages because competitive pressures prevent them from passing that cost down the food marketing chain. In contrast, he noted, the large companies that use tomatoes in fast food or retail chains are better able to absorb a higher wage. In this example, in Wilde’s opinion, CIW’s decision to focus on downstream buyers was a “very clever, wise, astute decision.”

The History of Food Prices

Over the past six decades, food prices have risen and fallen, Wilde continued. The oil price crisis in the 1970s, he observed, along with weather and other production problems during that period, led to a sharp price spike. More recently, prices spiked again in 2008 and 2011.

Focusing on the past 30 years, Wilde described an initial long period of productivity growth in agriculture and trade that was associated with a fairly low price environment (from 1990 through the early 2000s) (see Figure 2-5). “People forgot to worry any longer about scarcity,” he said. Two things then occurred as a result of changes in the agricultural economy, including increased use of food stocks for biofuels (in the early 2000s), which essentially removed those stocks from the human food supply. First, Wilde elaborated, prices started rising; second, prices fluctuated chaotically.

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FIGURE 2-5 Food and Agriculture Organization (FAO) food price indices over the past 30 years.
NOTE: The y-axis depicts the FAO food price index; the x-axis depicts the year.
SOURCE: Presented by Parke Wilde on August 1, 2018.
Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

He explained that changes in abundance from one year to the next are smoothed out as long as there is enough agricultural stock in the system. But without enough agricultural stock in the system, after several years in a row of low harvest and high demand, the stocks continue to decrease until they hit a point when they can no longer adjust smoothly from year to year, causing sudden price spikes. This, Wilde added, is what occurred in 2008 and 2011 (CFR, 2013). He recounted how both of those price spikes were associated with riots in developing country capitals and a great deal of fear around the world. After such price spikes, he continued, when prices fall again, as they did in the mid-2010s, people again start worrying about overproduction, excessive abundance, low prices, and how difficult it is for farmers to earn adequate livelihoods. Wilde cautioned, “We need to be worried about both types of conditions: high prices and low prices.”

Thoughts on the Future of Food Prices

Wilde went on to note that USDA produces official projections of the future of food prices and other agricultural variables under certain assumptions. The projections for key row crops (soybeans, wheat, corn) through 2027, he reported, are neither as low as prices were in the 1990s or 2000s nor as high as the price spikes of 2008 and 2011. Nor do USDA’s projected prices fluctuate as they have in the past decade. Similarly, Wilde continued, projected livestock prices through 2027, including those for beef cattle, broilers, and hogs, are somewhere in the middle. He explained that meat prices depend a great deal on how much is consumed, and while chicken consumption in the United States has been rising significantly in recent decades, USDA is forecasting a modulation of this increase. He added that consumption of both beef and pork has been declining somewhat and is expected to hold steady (USDA, 2018). In sum, he said, USDA is not predicting any radical change in where Americans get their protein, but is expecting more of the same. “That might or might not be the case,” he observed.

Of the USDA price projections in general, Wilde said, “Not everybody agrees with this reasonably rosy view.” He cited several assumptions underlying the projections. The first is mid-range economic growth in the United States (2.1 percent) and fairly good economic growth in developing countries (3.7–4.6 percent). Another assumption is moderate population growth (<1 percent globally, 1.1 percent in developing countries), which Wilde said is to be expected only if developing countries experience no economic collapse, women and girls continue to be educated at higher rates, and other social changes proceed well. As yet another assumption, Wilde cited moderate increases in energy prices (up to $80/barrel of oil), which he cautioned does not account for how climate change may impact

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

the status quo. He noted that the USDA document containing these projections mentions neither climate nor warming, and it mentions drought only once, in an explanation of how future events and assumption variables are not certain. Additional assumptions, he reported, are no change in agricultural policy, although farm payments may rise; an initial increase in use of biofuels, but then a fallback; and current trade agreements remaining in place (USDA, 2018).

Wilde recounted how he reviewed a 2015 book, The End of Plenty, by Joel Bourne, Jr., which tells of the author’s visits to farms in the Ukraine, places where fish are harvested in the middle of the Pacific, and elsewhere (Wilde, 2015). As a result of these trips, Wilde said, Bourne became very concerned about the future of abundance. In his book, the economist Malthus is a major figure. At the end of the book, the writer describes his trip to Bath Abbey in the United Kingdom to look for Malthus’s gravesite. But he could not find it, Wilde said, and discovered later that the grave is hidden under the abbey’s pews. The lesson, Wilde quipped, is that Malthus is “not yet ready to be resurrected.” He warned, again, that while it is important to think about the possibility of price rises, it is also important to think about the possibility of overproduction and low prices that will threaten farmers’ livelihoods.

Food Prices and Resilience

People need to focus not just on wishing for low prices, Wilde concluded, but also on the fundamental goals one hopes to achieve through low prices—namely environmental quality, healthy eating, a thriving economy, and low hunger and poverty. “Let prices be prices,” he urged. “Let them do what they do well,” which is to clear demand and supply quantities. He called for pursuing a sustainable diet strategy that does not assume just one future, but accounts for conditions of both scarcity and abundance.

DISCUSSION

Following Wilde’s presentation, he, Drewnowski, and Fanzo participated in an open question-and-answer period with the audience, summarized here.

The Role of Technology

Earlier in the session, while introducing the speakers, Clydesdale had mentioned Sylvia Rowe’s singling out of the banana as an exemplar of the challenges to achieving a sustainable diet (see Chapter 1). He had suggested that GMO technology may be the only way to deal with some of

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

the sustainability issues related to the banana supply chain, raising both technological and social challenges. At the end of the session, he noted that there had been very little mention of technology during the presentations. He asked about the role of technology in what he described as “communities of plenty” versus “communities without plenty.” He was curious about the role of technology in production, but also postharvest.

In response, Wilde commented on the importance of productivity growth and its major role in the low price environment of the 1990s and 2000s, even in the face of the opposition to GMOs and other new technologies. He said he suspects that some of this opposition will ease over the next few years as products come to market for the first time that are more visibly useful from a consumer perspective.

Fanzo agreed with Wilde that there is a role for technology in the agriculture sector and added that there is also a role for technology in shopping for and purchasing food. In China, for example, many 18- to 25-year-olds use an app on their smartphone to buy their food, which is delivered to their house cooked and ready to eat (CNBC, 2017). Even in the United States—in Seattle, for instance—Amazon is using “walk-in, walk-out” technology, much like that of driverless cars, in its new grocery stores. Instead of purchasing their food in checkout lines in which they engage with actual people, Fanzo elaborated, consumers take the foods they want to purchase off the shelves and walk out of the store without pulling out a credit card or money or even scanning the products. Purchases are all tracked through the consumer’s phone. This technology raises “huge sustainability issues,” Fanzo argued, including employment issues and issues around waste from prepackaged foods.

Drewnowski also agreed with Wilde that technology plays major roles in production, either by increasing yields or through fortification, but cautioned that more production does not necessarily lead to greater food security and public health. “There are all kinds of steps in between,” he said. For example, he noted, more rice production does not solve the malnutrition problem in Southeast Asia. From a consumption perspective, he views technology as playing a role in helping to ensure a nutrient-rich diet for everyone, either through the reformulation of processed foods or perhaps through the fortification or biofortification of foods.

Finally, Clydesdale observed that technology has a role in dealing with waste as well.

How Policy Makers Make Decisions

There was some discussion in response to Fanzo’s description of the way policy makers make decisions. Barbara Schneeman, University of California, Davis, expressed appreciation for Fanzo’s description of that

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

process and agreed that scientists need to think about how they fit into this paradigm. In her experience, science is necessary, but not sufficient; economic and legal elements are needed as well to create the political will to take meaningful action.

Denise Eblen, USDA, remarked that she always worries when someone says the science exists, and the challenge is to translate that science into policies. She mentioned how, in her past work at the National Institute of Food and Agriculture, increased production of food always drew greater interest than food safety or nutrition and was viewed as the biggest “bang for the buck.” She asked how she, as a policy maker, can persuade other policy makers that it is not enough to produce food; rather, food must also be available, socially acceptable, and so on so that in 20 years, she is not looking back and thinking, “If only we had done that back then.”

Drewnowski saw a connection to prices. There was a time when eating more calories meant getting more nutrients, he observed, but that time has passed, and today, people can eat extra calories without getting more nutrients, particularly if they are eating cheap foods. The connection between calories and nutrients is completely price-dependent now, he added. He encouraged USDA to update and revise the National Food Prices Database, noting that its last revision was in 2004. Having an updated database would be extremely helpful, in his opinion, as it would allow researchers to examine what it costs to have a healthy diet.

Wilde reframed Eblen’s question: How does one communicate effectively and persuasively to policy makers and diverse constituencies to get them to understand the range of considerations that affect the same issues? “I have been stumped by that one so long,” he said, “and have absolutely no answer.”

Fanzo stressed, as she had during her presentation, that while much remains to be learned about sustainable diets, time is limited with respect to climate change. “We need to act now,” she said. “We need to think about the evidence we have now.”

Trade-Offs

With respect to the trade-offs and compromises entailed in sustainable diets, Schneeman asked, “If I can’t have it all, what do I have to give up?” Drewnowski replied that the role of modeling is to reveal the necessary compromises, or what the “sweet spot” is. He suggested that it is probably context dependent, with the right diet for one population being different from the right diet elsewhere. He mentioned recently having been in Southeast Asia as part of a study on nutrition transition and observing that people’s choice of meat protein is highly dependent on culture, religion, and geography. He related that in one focus group, a man from Sulawesi,

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

Indonesia, said his family had been eating rice and fish for the past 30 years. To some people, that sounds like sushi, Drewnowski said, and they might think it was wonderful. But then the man’s eyes started tearing up, and he said that he wanted to be able to give his family something that he could not afford, like chicken. “Aspirations and desires are very different,” Drewnowski said. “We should not take them for granted.”

From the perspective of a policy maker, for whom “it is all about making it to the next election cycle,” Fanzo suggested that the “sweet spot” is short-term things they know will resonate with the people they prioritize. The question then is whether climate change is “one of those things that resonates? Is it visceral enough for people?” On the other hand, Schneeman pointed out that not all policy makers are elected officials; many are career staff.

Food Waste

If one believes that 40 percent of food is being wasted, Food Forum member Erik Olson, Natural Resources Defense Council, asked, “How is that issue being addressed in discussions on sustainable diets?” He commented on the enormous amount of wasted resources, such as cost, energy, and water, as well as emitted GHGs, embedded in all of that wasted food, and wondered why that had not been a prominent part of the session’s discussion.

Wilde replied that he suspected that the 40 percent figure, as large as it is, refers to total food waste in the system. The more interesting figure for him is the estimate of economically recoverable food waste, that is, the amount of economically recoverable food that actually could be added back to the food supply. This amount changes, he said, depending on what is being used to save that food and on prices. He urged everyone to always read the “smaller number” (i.e., the amount of economically recoverable waste) in any report on food waste.

Human Health Costs and Other Externalities

While Olson said he was pleased that GHG costs are beginning to be integrated into conversations on the cost of food, as discussed by Drewnowski, he wonders how human health costs and other externalities besides GHG emissions are being addressed. For example, what about the costs to humanity of the obesity crisis? He asked whether there were any efforts to consider these other costs.

Drewnowski pointed out that the impact of diet on health would be addressed later in the workshop and that it is very much part of the modeling efforts around sustainable diets. With respect to other environmental

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

costs besides that of carbon, he explained that it is difficult to obtain data on other aspects of the environment. Moreover, what data do exist often are region-specific. For example, data on water use from the Netherlands do not necessarily apply to southern California, and data on pasture in Switzerland do not necessarily apply to Australia. But Drewnowski agreed with Olson that other costs need to be considered. He called for a model that looks at the hidden costs of cheap diets in particular, while also noting that such costs cannot be separated from low wages, employment, and migration. Health is very much an outcome of food, he argued, but it cannot be linked entirely to the food choices people make. He underscored the importance of also looking at what drives food choices in the first place and referred again to the sharp social gradient of the obesity epidemic.

Cultural Shifts

For food companies to sell a more sustainable product, that product must be culturally relevant, Katya Hantel, Conagra Brands, remarked. “We have to attract consumers,” she stressed. She added that in this regard, cultural relevance appears to be the most malleable criterion, especially in the current age of global connectivity. She pointed to insect flour as an example. In the United States, consumers can now purchase a protein bar that is made of insect flour, representing a shift in cultural appropriateness. She asked to what extent one can rely on what is culturally appropriate today, given such shifts. She also asked about the role of trying to shift what is culturally appropriate to encourage more sustainable diets.

Fanzo agreed that not only do trends shift, but different cultures tap into different trends. For example, she noted, today in the United States, sustainability is a trend, while in England, veganism is on the rise. She added that in many low- and middle-income contexts, what people tap into is more about achieving a better lifestyle and aspiring to become something, and food is a big part of that aspiration. She relayed what she had heard recently from someone in advertising: that people do not buy food because it is healthy or environmentally sustainable; rather, they buy food based on hope. “Why do we have Beyoncé advertising Pepsi?” Fanzo asked, replying because it taps into that desirability, that hope. In Kenya, she observed, fast food is not something people eat in their shambas—it is something they aspire to. “It is urban. It is modern. It is clean. It is safe,” she said. In her opinion, that is what is driving cultural shifts.

The Effect of Greenhouse Gases on Nutrient Density

Maha Tahiri, former food industry executive, asked whether the effect of the current environment, specifically GHG emissions, on the nutrient

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
×

density of food has been factored into the model Drewnowski had discussed (see Figure 2-3). Drewnowski replied that, although he had not factored this effect into that work, he had found in a recent study that GHG emissions, specifically CO2 emissions under controlled conditions, reduced the nutrient content of rice (Smith and Myers, 2018). He agreed with Tahiri that the current environment will have an impact on the future nutrient density of foods.

Suggested Citation:"2 What Are Sustainable Diets?." National Academies of Sciences, Engineering, and Medicine. 2019. Sustainable Diets, Food, and Nutrition: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25192.
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On August 1 and 2, 2018, the National Academies of Sciences, Engineering, and Medicine hosted a public workshop in Washington, DC, on sustainable diets, food, and nutrition. Workshop participants reviewed current and emerging knowledge on the concept of sustainable diets within the field of food and nutrition; explored sustainable diets and relevant impacts for cross-sector partnerships, policy, and research; and discussed how sustainable diets influence dietary patterns, the food system, and population and public health. This publication briefly summarizes the presentations and discussions from the workshop.

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