sustainable diets within sustainable food systems...food summit: ‘food security exists when all...

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12th European Nutrition Conference, FENS 2015, held at the Estrel Convention Centre, Berlin on 20–23 October 2015

Conference on ‘Sustainable food consumption’

Sustainable diets within sustainable food systems

Alexandre Meybeck* and Vincent GitzAgriculture and Consumer Protection Department, Food and Agriculture Organization of the United Nations, Rome,

Lazio, Italy

Sustainable diets and sustainable food systems are increasingly explored by diverse scientificdisciplines. They are also recognised by the international community and called upon to ori-ent action towards the eradication of hunger and malnutrition and the fulfilment of sustain-able development goals. The aim of the present paper is to briefly consider some of the linksbetween these two notions in order to facilitate the operationalisation of the concept of sus-tainable diet. The concept of sustainable diet was defined in 2010 combining two totally dif-ferent perspectives: a nutrition perspective, focused on individuals, and a globalsustainability perspective, in all its dimensions: environmental, economic and social. The nu-trition perspective can be easily related to health outcomes. The global sustainability per-spective is more difficult to analyse directly. We propose that it be measured as thecontribution of a diet to the sustainability of food systems. Such an approach, coveringthe three dimensions of sustainability, enables identification of interactions and interrela-tions between food systems and diets. It provides opportunities to find levers of change to-wards sustainability. Diets are both the results and the drivers of food systems. The driversof change for those variously involved, consumers and private individuals, are different, andcan be triggered by different dimensions (heath, environment, social and cultural).Combining different dimensions and reasons for change can help facilitate the transitionto sustainable diets, recognising the food system’s specificities. The adoption of sustainablediets can be facilitated and enabled by food systems, and by appropriate policies andincentives.

Sustainable diets: Sustainable food systems: Sustainability: Food security and nutrition:Mediterranean diet

There is now wide recognition that the global food sys-tem, today, is not sustainable. There are more than twobillion malnourished, almost 800 million undernourished,more than one billion overweight and obese. The major-ity of the poor and hungry are food producers. Food pro-duction and consumption are among the main drivers ofenvironmental degradation, threatening its own resourcebase. A third of the food produced is lost or wasted.According to the FAO, global food demand is projectedto increase by 60 % towards 2050 from 2007, driven bychanging consumption patterns and population growth(1).Numerous studies show the role of food consumptionpatterns and of their evolution in the increase of non-

transmissible diseases. Numerous studies link food con-sumption patterns and their evolution to pressures onthe environment. Many studies now point to synergies be-tween more healthy diets and reduced environmentalpressures, leading to the notion of sustainable diets, forhealthy lives and healthy ecosystems.

Sustainable diets and sustainable food systems (SFS)are increasingly explored by diverse scientific disci-plines(2,3). They are also recognised by the internationalcommunity and called upon to direct action towardsthe eradication of hunger and malnutrition and the fulfil-ment of sustainable development goals. The aim of thepresent paper is to briefly consider some of the links

*Corresponding author: Alexandre Meybeck, email [email protected]

Abbreviations: FSN, food security and nutrition; GHG, greenhouse gases; HLPE, High Level Panel of Experts on Food Security and Nutrition; SFS,sustainable food systems.

Proceedings of the Nutrition Society (2017), 76, 1–11 doi:10.1017/S0029665116000653© The Authors 2016 Food and Agriculture Organization of the United Nations under license to Cambridge University Press

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between these two notions to pave ways for operationa-lising the concept of sustainable diets.

A series of international declarations and conferenceshave promoted SFS, and stressed their importance to en-sure food security and nutrition. In 2012, the SecretaryGeneral of the United Nations launched, during theConference on Sustainable Development, Rio + 20, theZero Hunger Challenge, emphasising the central role offood security and nutrition (FSN) for sustainable devel-opment. The zero hunger challenge includes five objec-tives that complement each other: 100 % access toadequate food all year round; zero stunted children <2years; all food systems are sustainable; 100 % increasein productivity; zero food loss. Two of these objectivescould be qualified as results (eradication of hunger andof child malnutrition), two of them could be qualifiedas means, and integrate the three dimensions of sustain-ability, economic, social and environmental. The fifthand central one, all food systems are sustainable, isboth a mean and a result, as well as a way to inscribeit in the long term.

In 2013, SFS were a topic of discussion in theConference of FAO and the theme of World Food Day,with the slogan ‘healthy people depend on healthy foodsystems’. The second International Conference onNutrition, organised by FAO and WHO in November2014, adopted the Rome Declaration on Nutrition(4)

that manifests a holistic approach, recognising ‘that theroot causes of and factors leading to malnutrition arecomplex and multidimensional’, stressing the need to ‘en-hance SFS by developing coherent public policies fromproduction to consumption’. The framework of actionto guide the implementation of the declaration containsa specific list of recommended actions for SFS promotinghealthy diets, even though many of the other recom-mended actions contribute to this objective.

The 2030 Agenda for Sustainable Developmentadopted by the General Assembly of the United Nationson 25 September 2015 reaffirms a commitment for aworld where ‘food is sufficient, safe, affordable and nutri-tious’(5). Sustainable development goal 2 calls, by 2030, to‘end hunger, achieve food security and improved nutritionand promote sustainable agriculture’. It is the first timethat an international commitment is taken to eradicatehunger (rather than to reduce it). Interestingly, sustainabledevelopment goal 2 mentions also a means or directions todo so, ‘promoting sustainable agriculture’. Sub goal 2·4 isto ensure sustainable food production systems and imple-ment resilient agricultural practices that increase product-ivity and production, help maintain ecosystems, andstrengthen adaptation to climate change. However, it isto be noted that the sustainable development goals limitedthemselves to agricultural production systems, instead ofreferring to food systems. One has to refer to goal 12:‘Ensure sustainable production and consumption patterns’to go beyond production, with subgoal 12·3: setting a 50% per capita target for the reduction of food losses andwaste along the whole supply chain by 2030, being theonly one specifically directed to food. Goal 12 alsomakes reference (subgoal 12·1) to the implementation ofthe 10-year framework of programme on sustainable

consumption and production patterns, under which arecontained seven sectoral programmes, one being on SFS.

We thus adopt here a broader approach aiming tocharacterise the sustainability of diets within the sustain-ability of food systems. To do so first we analyse the rela-tions between the two notions of SFS and sustainablediets. A brief description of the symptoms of the unsus-tainability of the food system, at global level, enablesus to better characterise the issues at stake and the roleof global diets. This leads to consideration of how sus-tainable diets could be the key to more SFS, startingfrom analysing what could be the characteristics of sus-tainable diets. The final section, building upon the rela-tions and interactions between sustainable diets andfood systems attempts to identify pathways for progress.

Sustainable food systems?

Food systems and diets

Diets and food systems are closely linked. However, thenotion of food system is generally focused on food; wepropose here to revisit the notion in relation to diets.

A diet is a selection of foods, eaten by an individual,chosen between those made available by the food system.Conversely the sum of diets creates the overall food de-mand that directs food systems. Diets are thus both a re-sult and a driver of food systems. Therefore, approachingfood systems by adopting the perspective of diets canbring operational insights to the issue of the evolutionof food systems towards sustainability. Diet(s) can be agood entry point to see what can be done individuallyand collectively to improve food systems (and the mar-gins of manoeuvre).

Hammond and Dubé(6) proposed, as part of a systemsframework for food and nutrition security, a definition ofagrifood systems, focused on food production and linkedto two other systems: the environmental system and thehealth and disease system; the interactions of the threesystems determining outcomes on individuals.

Sobal et al.(7) proposed an integrated conceptualmodel of the food and nutrition system emphasising afocus on nutrition and the links between food produc-tion, food consumption and nutritional health. Itdefines the food and nutrition system as ‘the set of opera-tions and processes involved in transforming raw materi-als into foods and transforming nutrients into healthoutcomes, all of which functions as a system within bio-physical and sociocultural contexts.’ It identifies threesubsystems: the producer subsystem, the consumer sub-system and the nutrition subsystem, each flowing intothe subsequent one. Focused on the linear relations be-tween these three subsystems it is less comprehensive inits coverage of determinants of food systems, heredescribed as part of biophysical and sociocultural con-texts. It further identifies several systems that interact inmany points with the food nutrition system. These sys-tems, including the health care, economic, cultural, eco-logical, governmental, transportation systems, havetheir own specific orientations and interact with eachother. This approach puts the consumer at the centre of

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the system, as an intermediate between food productionand nutrition outcomes. It is thus particularly usefulfor the consideration of diets, within food systems.

More recently, building upon these and a range ofother works(9–12) the High Level Panel of Experts onFood Security and Nutrition (HLPE) proposed a com-prehensive, descriptive definition:

‘A food system gathers all the elements (environment, people,inputs, processes, infrastructures, institutions, etc.) and activ-ities that relate to the production, processing, distribution,preparation and consumption of food, and the outputs ofthese activities, including socio-economic and environmentaloutcomes.’(13)

We propose to build upon the HLPE definition of foodsystems and to integrate the idea of linear exchanges be-tween production and consumption, focusing on diets. Inaddition, we emphasise two dynamic domains interactingwith food systems: environmental changes and socialand economic drivers as well as two other domains inter-acting with individual food choices and diets: attitudes andlifestyles on one side, health on the other (see Fig. 1).

Notions and definitions of sustainable food systems andsustainable diets

We try here to delineate the relationships between dietsand food systems, in order to be able to concretely assessthe sustainability of diets, intended as their contributionto the sustainability of food systems and ultimately tofood security and nutrition. The internationally agreeddefinition of food security dates from the 1996 WorldFood Summit: ‘Food security exists when all people, atall times, have physical and economic access to sufficient,safe and nutritious food that meets their dietary needsand food preferences for an active and healthy life’(14).This definition identifies four dimensions of food secur-ity: availability of food, accessibility (economical andphysical), utilisation (the way it is used and absorbed)and stability of these three dimensions.

The HLPE, in line with the original broad approach ofsustainability, has provided a definition of a SFS orientedby its capacity to ensure the positive outcomes of a foodsystem: food security now and for future generations: ‘Asustainable food system is a food system that ensuresfood security and nutrition for all in such a way thatthe economic, social and environmental bases to generatefood security and nutrition of future generations are notcompromised.’(13) The HLPE has thus formalised thelink between the two concepts of FSN and of SFS: thebasis is that there can be no FSN (short and longterms) without SFS. FSN for all, worldwide, and theconditions for their existence over time, could be whatultimately characterises SFS.

How do sustainable diets relate to SFS? First, a diet isa notion that is person-centred, it is the set of food, bev-erages and nutrients that are consumed by an individualor by a community of individuals during a certain periodof time(15). However, when the question is which diet tochoose or to have, or what is an optimal diet, one has tobring in the picture elements that go beyond the dietstricto-sensu, both as impacted by the diet and as deter-mining the space of potential choices of each individual:economic, social and cultural conditions and constraints.

As defined in 2010, sustainable diets are those dietswith low environmental impacts, which contribute tofood and nutrition security and to healthy life for presentand future generations. Sustainable diets are protectiveand respectful of biodiversity and ecosystems, culturallyacceptable, accessible, economically fair and affordable;nutritionally adequate, safe and healthy; while optimis-ing natural and human resources(16).

Such a definition of sustainable diets, while embracingsome of the elements of the food system, does not makedirect reference to food systems. By introducing the SFSdefinition of the HLPE and how it relates to FSN, we de-duct a relation between the definition of sustainable diets(with their double dimension of individual sustainabilityfor health and of impact on global sustainability) andSFS:

‘A sustainable diet is a diet that contributes to the good nu-tritional status and long term good health of the individual/community, and that contributes to, and is enabled by, sus-tainable food systems, thus contributing to long term food se-curity and nutrition.’

This has two important consequences to understand howsustainable diets relate to SFS: First, the two notions arevery linked, which can help their common assessment.The strength of the contribution of the diet to the sustain-ability of the food system is what characterises the sus-tainability of the diet. Second, sustainable diets areboth an objective and an essential mean, a key driver,to achieve the transformation of food systems, which isneeded to achieve FSN.

The food system, at global level, currently, is notsustainable

From the above definition, the very function of food sys-tems is to provide food security and nutrition. As shown

Fig. 1. (Colour online) Food systems and diets(8).

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by current figures of hunger and malnutrition the globalfood system is not fulfilling its function. There is today atriple concern, often referred to as the triple burden ofmalnutrition, consisting first, of deficiencies in dietary en-ergy intake (hunger defined by FAO as chronic under-nourishment affecting 795 million persons according tothe latest estimate(17)); second, of nutrient deficiencies,such as iron, iodine and vitamin A, which affect sometwo billion people in the world; and third, from overnu-trition leading to overweight, estimated by WHO toinvolve 1·9 billion adults in 2014, and obesity, 600 mil-lion in 2014(18). In addition, 42 million preschool childrenwere suffering from overweight or obesity in 2013(18).These different malnutrition challenges, which veryoften coexist in countries, can also overlap at individuallevel (for instance obesity can coexist with nutrient defic-iencies), with correlated individual and public healthchallenges.

There are however differences in the way dietary pat-terns change across the world. Imamura and colleagueshave characterised changes in dietary patterns nationallyand regionally analysing information derived fromindividual-based national surveys(19). Focusing on twentydietary factors, they have modelled two different dietarypatterns: one based on relatively high consumption ofhealthy items, another based on relatively low consump-tion of unhealthy items, as well as a third one integratingall items, and derived a score for each pattern. They notesubstantial heterogeneity between countries, includingbetween neighbouring countries. Between 1990 and2010 patterns based on more healthy items improvedmodestly while patterns based on unhealthy itemsworsened to a greater extent; these trends being weaklycorrelated. Trends vary significantly by nationalincomes, with improvements on healthy items in higher-income countries; global worsening on unhealthyitems, particularly in middle-income countries, someimprovements in high-income countries but they remainamong the worst in the world. Importantly associationbetween socioeconomic status and diet quality variessignificantly for diet patterns based on unhealthy andhealthy items.

Also, there are concerns about the scale of some majorenvironmental impacts of food production. The produc-tion of food, including deforestation and other land-usechanges linked to expansion of production, is responsiblefor 24 % of greenhouse gases (GHG) emissions(20).Agriculture accounts for 70 % of freshwater withdrawalsglobally, and in many places exceeding the renewablepotential(21). Pollution of soil and water is due to overuseof nitrogen and phosphorus fertilisers, and improper useof pesticides. Agriculture is also one major factor ofbiodiversity loss(22,23), and at the same time agriculturalbiodiversity is decreasing: In the past 100 years, about75 % of the genetic diversity of agricultural crops waslost(24), and today more than half global plant derivedenergy comes from only three crop species: wheat, riceand maize(25).

The food system is producing, globally, enough foodbut is unable to ensure food security and good nutritionin the world today. And strikingly it performs

proportionally worse to feed its own participants. Themajority of the poor and undernourished people in theworld are living in rural areas, depending on agriculturalactivities for their subsistence. This is why sustainabilityconcerns for food systems expand in fact well beyondthose of their inadequate environmental and natural re-source use performance, questioning substantially theireconomic and social features.

Sustainability challenges for the future

According to FAO estimates(1), business as usual projec-tions of food consumption, due to increased populationand, to a more important extent, to worldwide dietarychanges, is expected to grow by 60 % by 2050 comparedwith 2007. There are major differences between countriesboth in increase of food consumption and in changes indietary patterns, but in the countries experiencing foodconsumption increase, patterns are generally changingtowards more livestock products, vegetable oils andsugar. These three food groups together now provide29 % of total dietary energy supply of the developingcountries, a share up from 20 % three decades ago, andprojected to rise to 35 % in 2030 (in industrialised coun-tries the share has been about 48 % for several decadesnow).

Of particular significance is the projected increase ofthe global consumption of animal-sourced products.Such changes are expected to have a major environmen-tal impact, mainly evaluated in terms of GHG emissionsand land-use change(26). Some studies have described al-ternate scenarios. For instance Agrimonde(27) describes abaseline scenario, Agrimonde 0, with an increase of glo-bal demand of dietary energy of 83 %, and an abatedscenario Agrimonde 1, where the increase is 28 %. Thislast scenario supposes radical changes in consumptionpatterns and behaviours and in worldwide distributionof food, including a decrease of 25 % of the per capitaconsumption in Organisation for Economic Co-operationand Development countries between 2000 and 2050, with-out any income reduction, and a slowdown in the increaseof per capita consumption in emerging countries. Sucha scenario would require radical changes in consumers’behaviours, reduction in waste, and implementation ofefficient public policies to promote more balanced andhealthy diets.

Another study(28) elaborates scenarios based on diets,differing mainly by the proportion of meat: ‘westernhigh meat’, ‘current trend’, ‘less meat’ and ‘fair-lessmeat’. It concludes that under the fair-less meat scenarioit would probably be possible to feed the world with or-ganic crops and an organic livestock system, with a veryequitable distribution and an average daily intake of 11715 kJ (2 800 kcal) per capita of which 20 % of proteinis from animal origin. The western high meat diet, with44 % of protein intake of animal origin would also prob-ably be feasible, but only with a cropland expansion of20 %, intensive crop production and intensive livestockproduction.

These challenges for the future, given today’s unsatis-fying performance of food systems, economically,




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socially and environmentally, poses the question of theappropriate leverage points to improve the sustainabilityof food systems.

Is sustainable diet and consumption the key to reachsustainable food systems?

The very effectiveness of the concept of sustainable con-sumption and production is in fact grounded on the ideathat to increase sustainability of systems, both produc-tion and consumption, supply and demand, have to beconsidered. There are production choices and there areconsumption choices; increasing sustainability is a matterof both. To a certain extent, and still in many economies,consumption choices are bound to evolve in the, oftenrestricted, product space which production offers. Butin today’s world, with a space of consumption choices in-creasingly wide, there are greater prospects for consump-tion to drive production, for consumption choices toorient the choices that producers make (which products,how they are made), or globally to direct production to-wards the products consumers want to buy. In that regard,there are increasing opportunities for more sustainableconsumption patterns and choices to drive towards moresustainable production patterns.

Human and food systems dimensions of sustainable diets

Characterising sustainable diets requires first to distin-guish between the two dimensions of the definition ofsustainable diets (Fig. 2): on the one side, the nutritionand health dimension, assessed on persons, and on theother side the impact on the food system, and its sustain-ability, in all dimensions and measured at various levels.Assessing each dimension requires specific methodologic-al approaches and tools.

The composition of the diet has two main categories ofimpacts: on the individuals consuming it and on the foodsystem as a whole. The impacts on the individuals can beassessed by the nutritional characteristics of the foodsconsumed and/or, with a time lag, by the assessment ofcertain health characteristics known to be influenced byfood consumption. The composition of the diet drivesthe demand for and production of specific foods, with en-vironmental, economic and social impacts. Assessing thesignificance of specific dietary choices on sustainability offood system brings a series of challenges. Impacts cangenerally only be assessed using generic indicators andfigures unless the origin of the products can be tracedback and that there are means to better assess specificimpacts in the area of origin and along the food valuechain.

Looking at the nutrition dimension involves mainlyindividual-level indicators, but comes with its challenges.It impacts, and to a great extent determines, the nutritionstatus of the person. One main challenge for the assess-ment of nutrition and health impacts is how to makethe link between the sum of individual diets, the globalconsumption of the population, and the health status ofa population, at country level for example, given

heterogeneity of consumption, especially in a time ofchanging diets.

The function of a diet is to ensure proper nutritioncontributing to good health. There are numerous studiesand often diverging views on optimal diets from a healthperspective, and the aim of the present paper is not to re-view those studies. Some broad characteristics seem to begenerally considered to be correlated with better healthoutcomes. For instance, a recent review of studies onhealth effects of diets, organised by types (low carbohy-drates, low fat, low glycaemic, Mediterranean, mixed,Paleolithic and vegan) concluded with a broad aggrega-tion of evidence in support of diets comprising preferen-tially minimally processed foods, and comprising mostlyplants(30).

Diets that contribute to sustainable food systems

Most studies about the sustainability of diets focus onlyon environmental impacts, or combine them with healtheffects. Economic or social impacts of diets are generallynot considered. Even environmental impacts are oftenreduced in some of them, specifically GHG emissions,land use or land-use change and water use. Impacts onwater quality are much less mentioned and biodiversityis generally not taken into account or only through theproxy of land use, which does not enable proper consid-eration of agrobiodiversity nor of biodiversity in the field.Environment. A number of studies have applied life

cycle analysis to food products. A key issue here, from adiet perspective, is the functional unit used to makecomparisons. These can be agricultural productionmethods, food production methods, food items, meals ordiets. As noted by Heller, Keoleian and Willet in a criticalreview of life cycle analysis-based studies(31), the idealfunctional unit basis for diet comparisons should benutritionally based. An increasing body of scientificliterature analyses the parallels between the effects of dietson health and on the environment, using diets as the unitof comparison. One study adopting a global perspectiveand analysing the effects on health (type II diabetes,cancer, coronary mortality, all-cause mortality) and on theenvironment (GHG emissions and land-use change) offour diets (income dependent, Mediterranean, pescetarian

Fig. 2. Two dimensions of sustainable diets as a driver of changesat individual level and system level(29).




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and vegetarian) concluded that current dietary trajectoriesare at the same time greatly increasing global incidences oftype II diabetes, cancer and coronary mortality, and alsocausing significant increases of GHG emissions andcontributing to land clearing. Alternative diets would haveboth health and environmental benefits(26). Gill et al.(32),focusing on the effects of the nutrition transition inemerging economies note that the impact on environmentare significant and deserve proper consideration. Otherstudies(33,34) analyse the environmental consequences ofswitching to more healthy diets or the consequences onhealth of switching to more environmentally friendlydiets(35). Some studies analyse the environmental impactsof adopting diets respecting national dietaryguidelines(36,37). Most of them conclude that there aresynergies between more healthy and more environmentallyfriendly diets. One German study(38) calculated thatshifting to the official German dietary recommendationscould reduce GHG emissions by 11 %, land use by 15 %,blue water use by 26 % and energy use by 7 %.

These global results are contradicted by anotherstudy(37) in the US context, finding that shifting to USdietary guidelines to support healthy weight would in-crease energy use by 38 %, blue water footprint by 10% and GHG emissions by 6 %. This is mainly due tothe increase of fruit and vegetables which, in the USA,have a high energy (and thus relatively high GHG)and blue water footprint. The authors conclude that dif-ferences in production systems can have a significant im-pact on results and that there can be trade-offs betweenmore healthy and more environmentally sustainablediets.

Environmental impacts of a specific product can be verydiverse depending on methods of production, conservationand transformation. They can also be very variable accord-ing to local conditions; particularly for impacts on waterconsumption and quality, biodiversity, etc. Therefore,strictly speaking, assessing the impacts of a diet would re-quire to know where and how each of its componentshas been produced. Most environmental impacts are linkedto production, mainly in agriculture. However, for perish-able products in industrialised countries the impact on en-ergy consumption and GHG emissions (includingperfluorocarbures) of distribution, storage and consump-tion stages can be particularly important. With increasedconsumption of fresh or frozen perishable products the im-portance of these impacts is likely to grow.

At the global level, the environmental sustainability ofan archetypal average global diet can initially beappraised by looking at how such a diet potentiallyimpacts on the environmental sustainability of the foodsystem, at least for some global common indicators.The need for a clarification of the relationships betweendiets and food systems emerges when trying to calculateconcretely some of the indicators characterising the en-vironmental impact of a diet at lower levels, such asthe national level. Most of the diets are no longer deter-mined by what is locally produced, as it was for trad-itional food systems(39–41). The connection between adiet and a geographic area has loosened with globalisa-tion. Also, there is increasingly a disconnection between

the space of production and the space of consumption.And to a certain extent the very term Mediterraneandiet is misleading. It is geographic, localised, by name,while it is in fact increasingly using imported products,including from outside the Mediterranean area. It canalso be followed outside the Mediterranean region.

Impacts of a diet depend not only on its compositionbut on where and how each item has been produced,transformed, transported, stored and consumed. This iswhy when we want to assess environmental impacts ofa diet concretely we immediately get lost in scopes, scalesand data. The environmental impact of the sum of dietsof a country is not the environmental impact of the na-tional food production sector; there are exports andimports. In other words, what is assessed at consumptionlevel is not the sustainability of a food system but thecontribution of the diet to the sustainability of food sys-tems. Unless there is total traceability of all products con-sumed, with for each of them total information on thespecific impacts of their production, transformation,transport and conservation, impacts are assessed usingavailable, often generic, figures, and in reality, most ofthe time, point-based estimates.Economic and social significance. The economic and

social significance of dietary choices brings back the issueof the importance of agriculture, food transformation,retail and food preparation (including catering) sectors inthe national and local economies.

The livelihood of 2·5 billion people, living in ruralareas, depend on agriculture(42) and growth in the agri-cultural sectors is more than three times more effectiveat reducing poverty than growth in other sectors(43).Women comprise, on average, 43 % of the agriculturallabour force in developing countries, ranging from 20% in Latin America to 50 % in Eastern Asia andsub-Saharan Africa(42).

The agricultural sectors and food chains are markedby a high diversity, often coexisting within the samegeographical space, from very large-scale participantsoften better integrated with food chains and internationaltrade, to more traditional, small-scale units. Thesedifferent means of organisation often perform differentlyin relation to economic and social impacts, especiallyin relation to employment (including informal v.formal wage employment), working conditions, genderand especially women, job organisation andmarket power and repartition of the value added alongthe chain.

One of the main factors driving economic and socialimpacts of a specific diet (and also conditioning it) isfood prices. Low price of food, especially of healthyfood, condition the affordability of healthy diets.However, low prices reduce the income of producers,who constitute, worldwide, the majority of the hungryand malnourished. Low prices also risk reducing cap-acity and willingness to invest in agriculture, a conditionfor future food production. Social sustainability alongthe food chain also depends on the capacity for pricesto be fairly remunerative for all participants involved.It is determined by the relative prices of foods, betweenthemselves and as compared with income of consumers,




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as well as the way by which they contribute to the incomeof the various participants along the food chain.

Assessing sustainable diets

Combining dimensions. Theanalysisof the relationshipsbetween the conceptof sustainablediets, SFSonone side, andhealthy diets on the other provides a framework that can helpdesign a way forward to assess sustainable diets in concretesituations.

It could also help understand some of the conditions/drivers of sustainable diets, which could enable the de-sign of actions towards more sustainable diets(44).

There is tension to manage between going towards theperson, which is relevant for the ‘human health’ part ofsustainable diets; v. going towards the system and inte-grating at broader scales, which is relevant for examplefor sociocultural indicators.

Applying the sustainable diets definition concretely toactual diets encounters several methodological chal-lenges. It requires assessing the sustainability of an actualdiet from two totally different perspectives: from a nutri-tion perspective, to assess the potential effect on the indi-vidual’s health, and from a broader sustainabilityperspective, to assess its impact on the sustainability ofa food system, in all its dimensions: environmental, eco-nomic and social.

Therefore, taking these consideratiions altogether, wepropose that indicators of sustainable diets could bethose measuring the strength of the contribution of indi-vidual or collective dietary choices to the state of the foodsystem (measured by indicators of the sustainability offood systems). A consequence is that the measurementof the sustainability of diets is by nature very multidi-mensional: it reflects the multidimensionality of the indi-cators of SFS, and how the different components/variables describing the diet can influence them.

This is conforming to a conception of sustainable dietsas those diets which most strongly act to ‘shape’ the foodsystem towards more sustainability, in its various dimen-sions, environmental, economic and social. A difficultyhere is that in contrast to the increasing body of scientificliterature that analyses the parallels between the effects ofdiets on health and on the environment, there are farfewer studies assessing the economic and social implica-tions of dietary choices.

Combining scales. Finally, one critical issue is how todeal with the effect of spatial integration, from local toregional and global, when it comes to measuring theeffect of one diet on one food system. With longer andlonger food chains, expanding imports and exports,and increasing interconnection of food systems, dietsare more likely to have remote impacts, which can bedifferent from local impacts, and which will necessitateto a look at the food system at global scale. Theexample of meat consumption in Europe is a good one,as it drives a good part of the soyabean expansion inSouth America in order to provide feed. Anotherinteresting example is the success of quinoa. Is theincrease of quinoa consumption in developed countriesreally contributing to sustainable diets and how, given

all the dimensions of sustainability of food systems wetalked about, locally and remote?

The original discourse about sustainable diets was verymuch guided by an assumption that diets and food sys-tems are linked, and in particular that they share thesame spatial limits, with a broad equivalence betweenconsumption and production spaces. Such an equiva-lence is true at global level (summing all the individualdiets that compose it). It was to a great extent true in‘traditional’ food systems very much linked to a specific‘traditional’ diet, somehow homogenous, shared by ageographic community, and therefore sharing the samegeographical limits as the food production area. To a cer-tain extent this was true for the Mediterranean dietmodel, abstracted from traditional diets in theMediterranean (see Fig. 3). This is why it can be consid-ered as a case study of a sustainable diet (arrow 1). Thework done in that respect aims to devise a methodologicalapproach to consider actual diets in the Mediterranean inrelation to the notion of a sustainable diet (arrow 3)using their relationship to the Mediterranean diet model(arrow 2) as a pathway. As shown above, to assess the en-vironmental, economic and social dimensions would re-quire looking specifically at the food system to which adiet is linked and to assess it from a SFS perspective(arrow 5). Finally, the main question of interest in anyfood system could be the relationships between the dietand the food system (arrows 4) and how these determinethe sustainability of the diet (arrow 3) and of the foodsystem as a whole (arrow 5). Understanding these relation-ships and their dynamics could also be key to understand-ing drivers of change, including potential means toimprove the sustainability of diets and food systems.

This proximity of a diet to a food system, closely asso-ciated with a geographic area, is no more to be found formost modern diets. Furthermore, a diet within a particu-lar ‘system’ is not the same for everybody; consumptionwithin a food system is not homogenously distributed. Itis the sum of diets that creates global demand and thusdetermines impacts on food systems. This brings an add-itional difficulty to assess the impact of diets on food sys-tems, and often a way to deal with this is to look at the

Fig. 3. (Colour online) From concepts to actual diets: the case ofdiets and food systems in the Mediterranean(29).




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impact of average diets. However, from a nutrition andhealth perspective, the individual diets are important, ra-ther than the average.

How to make progress towards sustainable diets?

What drives what? Food system constraints and enablersto sustainable diets

Many drivers of food consumption choices and to theirexpression are to be found within food systems. If we as-sume that sustainable diets are both an objective and adriver of SFS, understanding the drivers of food choicesis of paramount importance to design ways to improvethe sustainability of both diets and food systems. Thisleads to particular interest for two specific groups ofparameters. The first covers economic, social and cul-tural parameters that, both inside and outside food sys-tems, can drive food consumption choices. The secondcovers those relating to consumption choices that go be-yond an interest in diet composition and take into ac-count characteristics such as quality, origin and modeof production. Such choices can have various impactson all dimensions of sustainability. Moreover, they canbe the expression of attitudes that are also groundingsome choices related to diet composition.

Sustainable diets are both constrained and enabled bythe food system. The state of the food system determinesthe space of possible diets, and therefore determines thepossibility to choose sustainable diets, given the availablespectrum of consumption choices and incentives, andthat these diets are available at the proper scale.

The food system is shaped by many drivers, its statusbeing the result of different diets, environmental, eco-nomic and social issues at different levels from local toglobal, etc. First, it is shaped by the sum of all thediets. The existence of unsustainable diets, or their pre-dominance and influence on the market, is in itself a con-straint to the emergence of sustainable diets at scale.Currently we are rather, globally, in an un-virtuous circle,by which the evolution of diets, as shown above, areshaped by and contributing to a more and more unsus-tainable food system. This interrelation expands, today,spatially: in one location, say at country level, diets are di-verse and one could say that several dietary patterns coex-ist. The food system is connected (and shaped by) a varietyof diets. Together with the importance of imports, diets atone place are connected to food systems at other places.Second, the food system is also shaped by many other dri-vers, such as food production and distribution costs, en-ergy and input prices, the cost of labour, agriculturalpolicies, as well as the evolution of incomes with regardto the price of foods, etc.

Prices and affordability of diets

One of the first determinants of food consumptionchoices (and of their feasibility) is price. From a con-sumer perspective, and especially poor net food buyers,the lower food prices are, the better; it facilitates diver-sified and nutritious diets, and favours capacity to

spend on other basic needs. Conversely, low food pricescan have direct negative environmental impacts by notdiscouraging food waste(45). They reduce investment cap-acity and thus economic sustainability. By driving theneed for low production costs they also encourage low-cost practices that can be environmentally damagingand drive low income and wages for food producersand workers, with important social impacts.

Another difficulty results from the increasing discrep-ancy between prices of healthy v. non-healthy foods.This is particularly important as those with low incomeare more sensitive to prices and price change. A system-atic review and meta-analysis covering ten countriesfound that healthier foods and diet patterns cost morethan less healthy options, with the difference betweenmuch healthier and less healthy options being significantfor low income families, but comparable with the societalcost of suboptimal diet quality, concluding that therewould be room for public intervention(46).

This divide between the price of healthy v. unhealthyitems tends to increase: in high income countries, thecost of the first category has risen more than the other dur-ing the past 30 years, and the same may apply in emergingeconomies, with prices of fruit and vegetables having risenmore than most foods including energy dense processedfoods(47). Price-driven substitutions from healthy to un-healthy food can be amplified in case of unhealthy foodsbecoming more affordable, when, as shown in the caseof the USA, consumption of food away from home, softdrinks, juice and meats were more responsive to pricechanges than other foods(48). Conversely, this would alsolead to possible higher effects on consumption of the tax-ation of such produce.

However, such findings do not necessarily mean that,systematically, healthier diets are always less accessible,such as in the case of the Mediterranean diet(49). Also,over time, some argue that income may become a weakerdeterminant of diets, giving thus broader scope for publicpolicy to have a real influence in the future(50). Thisdeserves to be discussed. On one side, it can suppress bar-riers to more healthy and sustainable diets if they weremore expensive. Conversely, it could reduce the effective-ness of any attempt to integrate negative externalities,whether for health or sustainability reasons, in food prices.

The potentially ambivalent (and at least multiform)role of prices with regard to sustainability and food se-curity calls for clarification, clearly separating food pricesas an indicator of access at consumption level, from itsuse and interpretation inside the food system at large,which requires breaking down the final consumptionprice in various components to better envision its rela-tionships with economic and social dimensions of sus-tainability. Such distinctions of level of impacts insidefood systems are also particularly important to betterunderstand, conversely, the potential impacts of chan-ging diets, on the different stages of food systems, as itwill impact prices and economic exchanges(51).

Food prices should therefore also be analysed in termsof their impacts on sustainability, with differentapproaches for diets and for food production, for in-stance. The contribution of food prices to the various




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dimensions of sustainability can thus be different whenconsidering only diets or food systems as a whole, par-ticularly when integrating a long-term perspective.Prices, however, are not the only parameter influencingfood choices. Other parameters enter in line, such as edu-cation and consumer information.

Consumer information

Consumers, by their choices, in terms of type of pro-ducts, quantity, quality (including production modes)direct production. Consumers are directed by the infor-mation made available to them. Producers can also an-ticipate consumer demand and its changes andpro-actively seek new markets.

Different parts of the food and nutrition systems havedifferent foci, goals and units and this can make commu-nication difficult between those involved(7). Nutritionistsorganise the world according to nutrients, producersfrom a commodity perspective, and consumers from ataste perspective(7). In that regard the decision to movefrom nutrient based to food based dietary guidelineshas been key to increase their readability for consumersand thus their effectiveness.

Simple messages about healthy diets can be obscuredby communication on various diets and products advo-cated by numerous participants(30).

Trends on dietary patterns towards more healthy itemsand towards more unhealthy items (see earlier) are notcorrelated which makes one wonder if it is not becausethese trends are driven by different policies and incen-tives, tendencies for increase of unhealthy items beingdriven by marketing and promotion of more healthyitems by government policies(19). There could also be re-luctance from policy makers to propose changes thatmight have a negative effect on economic sectors(50).

Conversely, too simple messages can have detrimentalimpacts on nutrition. For instance, in the UK, meat anddairy products make a considerable contribution to theintakes of fourteen nutrients for which intake is belowthe lower reference level(52). Hence, a recommendationfor reducing meat consumption would need to takeinto account the likely impacts on nutrient intake andpropose a more holistic diet change to compensate forthe induced changes.

Conclusion

How to operationalise changes or choices towards sus-tainable diets, combining arguments in the health andsustainability dimensions?

To trigger choices, there is a need to mobilise cultural,historical, geographical references and economic forces(including affordability). In fact, the introduction of sus-tainability criteria in the debate on healthy diets oftenacknowledges that the rationale for it is also to addone more reason to adopt them. It also needs to takeinto consideration convenience from the consumer per-spective. Cumulating several dimensions can lead to cu-mulating positive externalities associated with a diet

change. In particular, social and economic dimensionscan often more easily trigger change of some categoriesof participants. This could lead to envisage incentiveschemes, internalising benefits, taking the full sustain-ability implications into account.

A richer definition of sustainable diets, such as the oneproposed in the present paper, linking human health andthe three dimensions of sustainability of food systems,can seem more complex but we argue that in fact it isless prone to possible errors potentially created by uni-dimensional criteria or approaches, and more adaptedto the reality in which participants are working, andthus more operational. It needs more data, in all dimen-sions, environmental, social and economic, at the appro-priate scale. It also needs to accept moving from aninitial focus on win/win choices to accept informedchoices acknowledging trade-offs. This could enable par-ticipants in the food system to successfully implement thethree pathways identified by Tara Garnett(53): improveefficiency, restrain demand and improve governance.

In this discussion, what could be the role and use ofdietary guidelines? Can this instrument be used to discusssustainable diets? There is a competition between differ-ent discourses, typically the health discourse, and the sus-tainability discourse. We argue that it is important tohave a place to enable the confrontation of priorities.Discussion on what are sustainable diets needs to bedone with nutritionists, not only specialists of environ-ment or sustainable development. Dietary guidelines, ifwell-conceived, and adapted to national situations andpriorities can be a tool for food policies in general, to ori-ent the behaviour of the different participants, given themultiplicity of objectives. Some countries have recentlyintroduced explicitly sustainability as part of their dietaryguidelines (for example, Brazil, Germany, Qatar,Sweden); it is however too early to draw conclusionsabout their implementation.

Acknowledgments

The views expressed in this publication are those of theauthor(s) and do not necessarily reflect the views or pol-icies of the Food and Agriculture Organization of theUnited Nations.

Financial Support

This paper was prepared as part of the FAO/UNEP sus-tainable food systems programme supported by the SwissFederal Office of Agriculture.

Conflicts of Interest

None.

Authorship

Both authors were jointly responsible for all aspects ofpreparation of this paper.




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