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Research coupling human nutrition and sustainability concerns is a rapidly developing field, which is essential to guide governments’ policies. This critical and comprehensive review analyzes indicators and approaches to “sustainable healthy diets” published in the literature since this discipline’s emergence a few years ago, identifying robust gauges and highlighting the flaws of the most commonly used models. The reviewed studies largely focus on one or two domains such as greenhouse gas emissions or water use, while overlooking potential impact shifts to other sectors or resources.
- sustainable healthy diet
- food environmental sustainability
- socioeconomic sustainability
- indicators
- constraints
- costs
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1. Introduction
Environmental degradation and malnutrition, in all its forms, are both occurring at an accelerated pace around the world. While the causes are complex, unhealthy diets coupled with unsustainable food systems can be considered among the main contributors to these global burdens [1].
Referring to environmental sustainability, currently, the global food system is the largest freshwater user: agriculture alone accounts for 70% of freshwater withdrawn in the world [2]. Agriculture is also responsible for 21–37% of total greenhouse gas (GHG) emissions [3] and covers approximately 49–51% of global ice-free land surface, with grazing land representing 37% and croplands representing approximately 12–14% [4]. Intensive and unsustainable agricultural practices and pollution can also trigger biodiversity loss [5].
In regard to the health component, currently, an estimated 821 million people are undernourished, 151 million children under five years of age are stunted, 613 million women and girls aged 15 to 49 suffer from iron deficiency, and, on the other side, 2 billion adults are overweight or obese [3]. Nowadays, unhealthy and unbalanced diets pose an increased risk to morbidity and mortality.
The challenge of achieving healthy diets is coupled with the challenge of attaining sustainable food systems [6]. While food production contributes to natural resource depletion and diets should improve to overcome malnutrition, sustainable food consumption and production could also be considered an opportunity for enhancing human health and environmental sustainability.
In 2011, Riley and Buttriss raised the question on “which dietary patterns are both healthy and sustainable?”, although they were not able to provide a complete answer due to the complexity of the issue [7]. Given the divergence of approaches, in 2019, the FAO and WHO held a consultation and coined the concept “sustainable healthy diets”. This was defined as:
“dietary patterns that promote all dimensions of individuals’ health and wellbeing; have low environmental pressure and impact; are accessible, affordable, safe and equitable; and are culturally acceptable” [1][1]
Sustainable healthy diets must combine all the dimensions of sustainability to avoid unintended consequences. However, currently, a few dietary guidelines take environmental sustainability into account, such as those of the Netherlands [8], Nordic countries [9], Germany [10], Brazil [11], Sweden [12], Qatar [13] and France [14]. Furthermore, the papers published in the literature generally focus on specific aspects of health, environmental or socioeconomic sustainability, sometimes leaving out one or two of the three components. Further development of encompassing indicators and data on all dimensions of sustainability is needed to make this concept complete, useful and effective.
In recent years, there has been an increase in the number of systematic reviews focused on sustainable and healthy diets, most of which also have a specific scope. For instance, some of the reviews have a limited geographical reach, focusing on one country such as the UK [15] or the USA [16]. Other reviews focus on a specific domain such as mathematical optimization studies [17] or labeling schemes [18]. Most reviews have a specific environmental scope, analyzing a single environmental aspect [19][20] or two or three environmental resources [15][21][22]. Some leave socioeconomic aspects out of the scope of review, instead focusing on the interlinkages between the environment and diets [23][24]. Few reviews combine socioeconomic and environmental performance with nutritional and health indicators [17][25][26], and only three of these compile [27] and recommend [28][29] criteria. There has been no comprehensive review highlighting a complete set of indicators coupled with an analysis of the gaps of knowledge and misconceptions from a multidisciplinary perspective. Thus, limited evidence is available on the trade-offs involved in selecting sustainable healthy diets.
In recent years, there has been an increase in the number of systematic reviews focused on sustainable and healthy diets, most of which also have a specific scope. For instance, some of the reviews have a limited geographical reach, focusing on one country such as the UK [15] or the USA [16]. Other reviews focus on a specific domain such as mathematical optimization studies [17] or labeling schemes [18]. Most reviews have a specific environmental scope, analyzing a single environmental aspect [19,20] or two or three environmental resources [15,21,22]. Some leave socioeconomic aspects out of the scope of review, instead focusing on the interlinkages between the environment and diets [23,24]. Few reviews combine socioeconomic and environmental performance with nutritional and health indicators [17,25,26], and only three of these compile [27] and recommend [28,29] criteria. There has been no comprehensive review highlighting a complete set of indicators coupled with an analysis of the gaps of knowledge and misconceptions from a multidisciplinary perspective. Thus, limited evidence is available on the trade-offs involved in selecting sustainable healthy diets.
2. Healthy Sustainable Diets in the Literature
2.1. Healthy Diet
Some of the latest studies point to the following dietary recommendations in promoting overall wellbeing and low risk of major chronic disease: (1) protein sources primarily from plants, including soy foods; other legumes; and nuts, fish or alternative sources of n-3 polyunsaturated fatty acids (PUFA) consumed several times per week with optional modest consumption of poultry and eggs and low intakes of red meat, if any, and especially of processed meat; (2) fat obtained mostly from unsaturated plant sources with low intakes of saturated fats and no consumption of partly hydrogenated oils; (3) carbohydrates primarily from whole grains with low intake of refined grains and less than 5% of energy from sugar; (4) at least five daily servings of fresh fruits and non-starchy vegetables; and (5) optional moderate dairy consumption [6][30][31][32]. These components can be combined in various types of omnivore, vegetarian, and vegan diets [6]. This nutritional guidance improves the intake of most nutrients. However, specific cases of dietary inadequacies require obtaining nutrients from dietary supplements or enriched foods [33][34][35][36][37][38][39][40]. The most accepted nutritional criteria proposed for a healthy diet are summarized in
Some of the latest studies point to the following dietary recommendations in promoting overall wellbeing and low risk of major chronic disease: (1) protein sources primarily from plants, including soy foods; other legumes; and nuts, fish or alternative sources of n-3 polyunsaturated fatty acids (PUFA) consumed several times per week with optional modest consumption of poultry and eggs and low intakes of red meat, if any, and especially of processed meat; (2) fat obtained mostly from unsaturated plant sources with low intakes of saturated fats and no consumption of partly hydrogenated oils; (3) carbohydrates primarily from whole grains with low intake of refined grains and less than 5% of energy from sugar; (4) at least five daily servings of fresh fruits and non-starchy vegetables; and (5) optional moderate dairy consumption [6,31,32,33]. These components can be combined in various types of omnivore, vegetarian, and vegan diets [6]. This nutritional guidance improves the intake of most nutrients. However, specific cases of dietary inadequacies require obtaining nutrients from dietary supplements or enriched foods [34,35,36,37,38,39,40,41]. The most accepted nutritional criteria proposed for a healthy diet are summarized in
.
Table 1.
Accepted nutritional criteria for defining a healthy diet (according to mainstream science) *.
| Criteria | Rationale | Relevance and Comments | References | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Comments | References | |||||||||||||
| Reduce intake of sugars | Dietary sugars have been linked to dental caries, obesity, and cardiometabolic diseases, including type 2 diabetes (T2DM). | Dietary sugars are not more harmful than excess of dietary energy. However, if the energy is excessive, a higher intake of added sugar (especially from sugar-sweetened beverages) might be associated with poorer diet quality and might increase the risk of caries, overweight, and T2DM. | [41][42][43][44][45] | [42,43,44,45,46] | ||||||||||
| Reduce intake of saturated fat as much as possible | Cardiovascular diseases (CVDs) have been linked to saturated fat intake based on observational studies. | Cardiovascular diseases (CVDs) have been linked to saturated fat intake based on observational studies with contradictory results. Some studies question further limiting the intake of such fats. Effect of a specific saturated fatty acid should be considered and not “generic saturated fat”. It is the higher intake of | trans | -fatty acids that is associated with greater risk of CVDs in a dose–response fashion. | [46][47][48][][53] | [47,48,49 | 49][50][51 | ,50 | ] | ,51 | [ | ,52 | 52 | ,53,54] |
147,148,149,150]. There are no standardized methodologies to perform LCAs for diets. Thus, authors add and discriminate environmental indicators in different ways, leading to a wide variety of studies that differ in scale and sets of environmental indicators, hindering data comparisons.
Environmental footprint approaches are able to pair food-production estimates with country-specific environmental footprints and compare them with planetary boundaries [150][151]. The footprint indicators used in sustainable diet studies are GHG emissions, freshwater use, land use and nitrogen, phosphorus application, biodiversity, energy and the ecological footprint [152][153][154][155][156][157][158][159][160]. However, many authors do not adopt these methodologies from a holistic perspective to assess the environmental impact from diets. The vast majority of studies take into consideration a single or few environmental aspects or impact categories (
Environmental footprint approaches are able to pair food-production estimates with country-specific environmental footprints and compare them with planetary boundaries [151,152]. The footprint indicators used in sustainable diet studies are GHG emissions, freshwater use, land use and nitrogen, phosphorus application, biodiversity, energy and the ecological footprint [153,154,155,156,157,158,159,160,161]. However, many authors do not adopt these methodologies from a holistic perspective to assess the environmental impact from diets. The vast majority of studies take into consideration a single or few environmental aspects or impact categories (
). Therefore, the results obtained from these kinds of assessments have to be interpreted rigorously as they may show a reductionist outlook of the whole environmental impact.
Table 2.
Indicators of an environmentally sustainable diet *.
| Environmental Concern | Indicators and Definition | Relevance and Comments | References | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Biodiversity loss | Biodiversity footprint: biodiversity loss related to products and processes. | Land conversion for crop and animal agriculture is the main driver of habitat loss, which currently continues to be the leading threat to biodiversity. Increasing crop yields, reducing deforestation and reducing meat consumption may be the most effective means to prevent biodiversity loss in future years. | [161][162][163][164][165] | [164, | |||||||||||||||||||||
| Supply side indicators | Those affecting the production and distribution of food | 165 | ,166,167,168] | ||||||||||||||||||||||
| Energy consumption and greenhouse gas (GHG) emissions | Energy use: energy used in the production and/or cooking of a product or process. | ||||||||||||||||||||||||
| Scalability and feasibility | Many of the assumptions of sustainable diet models are too rigid to resist empirical testing: |
| A key question for any sustainable diet concerns whether it can be empirically implemented on a large scale. | Food production, transport and consumption require large inputs of energy that have a significant environmental impact. Energy consumption is commonly linked to GHG emissions, as energy generation methods are some of the main emission sources. Global carbon emissions have increased by nearly 50% since 1990. Food production is one of the main causes of climate change. |
[217][218] | [218,219] | [166] | [169] | Reach a low | n | ‑6: | n | ‑3 ratio | ||||||||||||
| GHG emissions: release of greenhouse gases into the atmosphere. | Anti-inflammatory and anti-aggregatory activities are linked to | n | ‑3 PUFA. Conversely, the | [n | ‑6 PUFAs are considered precursors of pro-inflammatory and pro-aggregatory mediators. | 167][168][]178] | [170,171 | 169][170][171[ | ,172 | 172] | ,173 | [173] | ,174 | [174] | ,175 | [ | ,176 | 175 | ,177 | ][176][177] | ,178 | [ | ,179,180,181]The same ratio can be obtained with different individual amounts of | n | -3 and |
| Value chain approach | Value chains consist of involved actors (including public organizations and private firms) and the sequence of activities performed to bring a product from production to the consumer. Functioning supply chains require not only cooperation among supply chain actors (including farmers and between producers and other firms) but also rely on other supporting functions such as transport networks, standards and regulation enforcement, and credit markets. | n- | 6 PUFAs. The ratio is about 9.3 when linoleic, arachidonic, a-linolenic, docosahexaenoic, and eicosapentaenoic acids are only considered. This ratio is based on data association and not cause–effect studies. | [218][219][220][221] | [219,220,221,222] | [54][55][56][57] | [55,56,57,58] | ||||||||||||||||||
| Reduce intake of cholesterol | From the 1960s, epidemiological studies have suggested that dietary cholesterol contributes to the increased risk of CVD. | Evidence from observational studies conducted in different countries does not indicate a significant association with cardiovascular disease risk. Findings from intervention trials prove that dietary cholesterol does not increase plasma cholesterol. Likewise, the impact of dietary cholesterol on the immune response remains unclear. Not all subjects respond equally to dietary cholesterol. Dietary guidance focused on dietary patterns is more effective in improving diet quality and promoting cardiovascular health. |
[58][ | ||||||||||||||||||||||
| Production costs | Local and organic agriculture is less productive per hectare and more vulnerable to climate patterns and pests. These risks elevate production costs and must be considered for producers to undertake modes of production beneficial for both the environment and producers’ long-term business survival (especially in low-income countries). | [222][223][224] | 59][60][61][62][63][64][65] | ,63 | [ | ,64,65 | 66 | ,66 | ][ | ||||||||||||||||
| Carbon footprint: total GHG emissions caused by a product or process, expressed as carbon dioxide equivalent. | [179] | [182] | [225] | [223,224,225,226],67 | 67][ | ,68 | 68][69] | [59,60,61,62,69,70] | |||||||||||||||||
| Protein amount and source | The recommended protein intake level (0.8 g/kg) was derived as a minimum amount to avoid the loss of body nitrogen. Animal proteins have been linked to increased risk of many diseases (cancer, CVD, diabetes, osteoporosis, etc.) |
The recommended protein intake level (0.8 g/kg) was derived as a minimum amount to avoid the loss of body nitrogen. Higher protein intake can help maximize health benefits, particularly in older individuals. Amounts of protein above recommended do not appear to have harmful effects. | |||||||||||||||||||||||
| Food waste | It is unclear whether the relation animal proteins–diseases (cancer, CVD, T2DM, osteoporosis, etc.) is indicative of a causative effect or due to other diet and lifestyle factors. The role of plant or animal proteins in diseases or mortality is difficult to isolate. If there is a difference, it is reduced. Evidence to date is inconclusive. Globally, plant protein consumption is not more advantageous than animal protein consumption and vice versa. | Food waste and losses: decrease in the quantity or quality of food. Daily food waste per capita. | Globally, 30% of food is wasted annually (IPCC, 2019). In fact, avoidable food waste represents the largest fraction of overall food waste. The environmental footprints of an average person’s daily food waste are: 124 g CO | 2 | eq., 58 L of freshwater use, 0.36 m | 2 | of cropland use, 2.90 g of nitrogen use and 0.48 g of phosphorus use. | [70] | [4][71][[72[181] | [4 | 153]][180][73][74][75][76][77][78][79][80][81][82][83] | ,154 | [84] | [71,72,73,74,75,76,77,78,79,80,81,82,83,84,85] | |||||||||||
| , | 183 | , | 184] | ||||||||||||||||||||||
| Ethical and societal factors | It is necessary to consider the impact on farmers’ livelihoods, especially for smaller operators and those in underdeveloped economies reliant on livestock production for income and wealth. | [218] | [219] | Reduce intake of salt | Several dietary guidelines, health organizations and government policies recommend population-wide sodium restriction to prevent hypertension and related comorbidities such as heart failure. | The reduction in blood pressure is clinically relevant in the hypertensive population, especially in the elderly and Black ethnicity populations. There is not enough scientific evidence to recommend salt reduction in the general population. Health policies should focus on the target population. | [85][86][87][88][89] | [86,87,88,89,90] | |||||||||||||||||
| Food and vegetable biodiversity (agrobiodiversity) | Agrobiodiversity: variety and variability of animals, plants and micro-organisms that are necessary for sustaining key functions of the agro-ecosystem. There is currently no agreed, standard way of measuring agrobiodiversity in diets, food production or genetic resources. Indices include the Simpson’s diversity, Shannon’s diversity, and Dietary Species Richness. Beyond conventional measures, the Agrobiodiversity Index (ABD Index) is a method of measuring agrobiodiversity in a consistent, long-term manner to be applied across all pillars of sustainable food systems. The ABD Index assesses diversity in production, food markets, consumption, conservation, and seed systems. |
Species richness and diversity scores are usually related to adequate levels of micronutrients and presented as a promising solution for food security issues. Furthermore, maintaining genetic diversity is key for agricultural crops and livestock to be able to adapt—naturally or with human intervention—to future needs and challenges and be resilient to disturbances. | [182][183][184][185][186][187][188][189][190][ | ||||||||||||||||||||||
| Demand side indicators | Those affecting consumer food choices | 191 | ] | [185,186,187,188,189,190,191,192,193,194] | Intake of dietary fiber | Observational studies suggest a protective role of dietary fiber intake in colon cancer risk. | Colon cancer (CC) is an entity with different molecular subtypes. Epidemiological studies can mask these subtypes. Few studies consider environmental and molecular factors together. Regarding CC patients, increased fiber intake does not reduce the risk of recurrence. | According to FAOSTAT, in 2017, 50% of habitable land was used for agricultural purposes, of which 77% was used for animal feed. Land and soil degradation is a global challenge that may contribute to food insecurity, higher food prices and climate change in the near future. Overall, changing land use, high-yield cultivars and meat products are the main triggers of land deterioration. | |||||||||||||||||
| Availability | The availability of sufficient quantities of food of appropriate quality. | [218] | [ | [90][192][91][92] | [195 | [93] | |||||||||||||||||||
| Land use | [ | 94 | ] | [91,92,93,94,95] | |||||||||||||||||||||
| Land use change: the acquisition of natural resources for human needs (croplands and pastures), often at the expense of degrading environmental conditions. | ] | ||||||||||||||||||||||||
| 219 | ] | Reduce intake of palm oil (PO) | PO contains a high amount of saturated fat (40–50% of total fat). Their low consumption has been proposed as a policy to reduce deaths due to CVD. | Consumption of PO is associated with an increase in LDL cholesterol, but irrelevant clinically. Insignificant effects on fasting glucose and insulin. The studies to date do not establish strong evidence for or against PO consumption relating to cardiovascular disease risk and cardiovascular disease-specific mortality. | [95][96] | Land use: agricultural land required to produce crops for direct human consumption, as feed and for usage in industry and the energy sector, plus the area needed to produce the commodities’ packaging material. | [193] | [196 | [194] | ,197] | |||||||||||||||
| Resilience (stability) | Locally grown, organic, non-processed food lasts fewer days and must be more often purchased close to the production date. Such limitations must be accounted for to encourage the consumer to undertake dietary changes beneficial for the environment and guaranteeing the supply of food (especially in low-income countries). | [223] | [224] | [97][98][99][100][101] | [96,97,98,99,100,101,102] | ||||||||||||||||||||
| Reduce intake of dietary fats (butter and margarine) | Butter and margarine contain high amount of saturated fats. Saturated fats have been linked to high CVD risk. | Butter consumption was weakly associated with all-cause mortality in prospective studies. A theoretical analysis suggests that substituting butter with tub margarine may be associated with reduced risk of myocardial infarction. Beef fat was more effective in reducing LDL-cholesterol as compared with butter according to randomized trials. The number of studies remains insufficient to conclude a cause–effect relationship between fats and CVD. | Human carrying capacity: persons fed per unit land area. | [195] | [198 | ||||||||||||||||||||
| Affordability | ] | ||||||||||||||||||||||||
| A healthy/sustainable diet is more costly than a conventional diet. The environmental costs associated with a conventional diet are not high enough to compensate for the difference. | [ | 155][226][227][228][229] | [156,227,228,229,230 | [102][103][104] | [103,104,105] | ||||||||||||||||||||
| ] | Reduce intake of whole dairy products | Land footprint: amount of land needed to produce food (grasslands, croplands used to produce feed crops, and croplands used to produce crops for human food).Saturated fats from whole dairy derivatives have been associated with increased risk of chronic diseases including obesity, metabolic syndrome, T2DM, CVD, osteoporosis, and cancers. | Intake of dairy products was associated with a neutral or reduced risk of T2DM and a reduced risk of CVD, particularly stroke. The evidence suggested a beneficial effect of dairy intake on bone mineral density but no association with risk of bone fracture. Among cancers, dairy intake was inversely associated with CRC, bladder cancer, gastric cancer, and breast cancer, and not associated with risk of pancreatic cancer, ovarian cancer, or lung cancer, while the evidence for prostate cancer risk was inconsistent. Consumption of dairy products was not associated with all-cause mortality. | [196][197] | [199,200] | [105][106] | |||||||||||||||||||
| Forest cover loss: areas of forest cover removed related to land use changes. | |||||||||||||||||||||||||
| Acceptability | Beyond costs, consumer preferences are affected by a host of factors such as cultural values, family habits, religious beliefs, physical adaptations including those of digestibility and intolerance (different populations show different degrees of tolerance for certain foods), convenience (time to cook), etc., affecting what is acceptable for different consumers. | [230][231][232] | [231,232,233] | [107][108][109][110][111][112][113][114][115][120][121] | [106,107,108 | [116 | ,109 | ] | ,110 | [ | ,111,113,114,115,116,117 | 117][118][119 | ,112 | ] | ,118,119,120,121,122] | ||||||||||
| Reduce or suppress intake of red meat | From the 1970s, epidemiological studies have suggested that cancer and CVD risks are linked to red meat. Saturated fat, | heme | iron, N-nitroso compounds, and sialic acid have been implicated as causes of the increased risk. | [198] | [201]After multivariate adjustment for dietary and non-dietary risk factors, total, unprocessed, and processed red meat intake were each associated with a modestly higher risk of CVD. Meats, meat products and meat derivatives are inconsistently classified or misclassified into food groups when dietary questionnaires are applied. Studies examining the relation between the consumption or avoidance of meat and psychological health varied substantially in methodologic rigor, validity of interpretation, and confidence in results. Most studies, and especially the higher quality studies, showed that those who avoided meat consumption had significantly higher rates or risk of depression, anxiety, and/or self-harm behaviors. |
[122][123][124][125][126][127][128][129][130][131][132][133][134] | [123,124,125,126,127,128,129,130,131,132,133,134,135] | ||||||||||||||||||
| Dietary quality index | |||||||||||||||||||||||||
| Access equality | Income inequality increases the likelihood of severe food insecurity. The likelihood of being food insecure is higher for women than men in every continent. | [216] | [217] | An index combining the above criteria would allow the objective assessment of diet quality. Such indices would facilitate the implementation of dietary guidelines. | From the 1990s, 50 more indices have been proposed based on nutrients, foods or combining the two. Most recent proposals include inflammatory or cardiovascular risk biomarkers. The main limitations of these indices include: a non-standard methodology, “a priori” scoring, estimation of nutrient and biocompound intakes by questionnaires, failing to distinguish between some food types, difficulty in establishing a strong dose–effect relationship, inclusion of subrogated biomarkers, exclusion of different ethnic groups and phenotype/genotype profiles, poorly defined “lifestyle”, etc. Some recommendations obtained from these indices are unrealistic since they propose food substitutions that nutritionally are not interchangeable. |
[135][136][137][138][139][140][141] | [136,137,138,139,140,141,142] | ||||||||||||||||||
Some studies analyzing the association between health and diet are based on preconceived concepts and established hypotheses that do not support the cause–effect results and do not take into consideration the sustainability of the assessed diets. A balanced and healthy diet should be based on available, accessible, affordable, safe and culturally acceptable food and allow guaranteeing socio-economic and environmental sustainability.
2.2. Environmentally Sustainable Diet
The two main approaches used to address the environmental sustainability of diets and food systems are life cycle analysis (LCA) and environmental footprints. LCA assesses the environmental impact of a product from resource extraction, manufacturing, and transport to use and end-of-life disposal [142]. Ideally, LCA studies cover every relevant environmental category. However, in the case of diet-related impact assessments, only a few environmental indicators are generally used to perform analyses. The most common and recurrent impact categories applied in these studies are climate change, freshwater use, land use, acidification, ecotoxicity, eutrophication, human toxicity, ionizing radiation, ozone depletion, particulate matter, photochemical ozone formation and resource depletion [143][144][145][146][147][148][149]. There are no standardized methodologies to perform LCAs for diets. Thus, authors add and discriminate environmental indicators in different ways, leading to a wide variety of studies that differ in scale and sets of environmental indicators, hindering data comparisons.
The two main approaches used to address the environmental sustainability of diets and food systems are life cycle analysis (LCA) and environmental footprints. LCA assesses the environmental impact of a product from resource extraction, manufacturing, and transport to use and end-of-life disposal [143]. Ideally, LCA studies cover every relevant environmental category. However, in the case of diet-related impact assessments, only a few environmental indicators are generally used to perform analyses. The most common and recurrent impact categories applied in these studies are climate change, freshwater use, land use, acidification, ecotoxicity, eutrophication, human toxicity, ionizing radiation, ozone depletion, particulate matter, photochemical ozone formation and resource depletion [144,145,146,
| Ecological footprint: biologically productive area people use for their consumption and pollution (i.e., crop-, grazing-, forest-, fish-, built-up and carbon-uptake land) to the biologically productive area available within a region or the world. | ||||
| [ | ||||
| 199 | ||||
| ] | ||||
| [ | ||||
| 200 | ||||
| ] | ||||
| [ | ||||
| 202 | , | 203] | ||
| Pesticide use | Chemical footprint: all chemical substances released into the environment which may ultimately lead to ecotoxicity and human toxicity impacts. | Pesticides used in the agricultural production phase are the main contributors to ecotoxicity and human toxicity episodes. The use of such chemicals is not commonly addressed by sustainability approaches. | [148] | [149] |
| Nitrogen (N) application | N footprint: total amount of N released into the environment during the food chain as emissions of nitrous oxide, nitric oxide, ammonia or molecular nitrogen to the atmosphere, or as nitrate or organic nitrogen to the hydrosphere before the food product is supplied to the consumer. In some studies, it has been considered equal to N use. | A 50% increase in the N and P input to agricultural fields from 2010 levels will be required by 2050. N and P losses, agriculture intensification and dietary choices are responsible for eutrophication in many parts of the world and are endangering many freshwater and coastal ecosystems. | [180][181][201][202] | [183,184,204,205] |
| N loss: nitrogen losses to the environment from agriculture (croplands and animal manure management). | [203] | [206] | ||
| Phosphorus (P) application | P footprint: total amount of P released into the environment as a result of food consumption. In some studies, it has been considered equal to P use. | [202][204] | [205,207] | |
| Water use and/or scarcity and pollution | Green water footprint: volume of rainwater consumed during the production process. Blue water footprint: volume of surface and groundwater consumed as a result of the production of a good or service. Grey water footprint: the grey water footprint of a product is an indicator of freshwater pollution that can be associated with the production of a product over its full supply chain. |
Agriculture (including irrigation, livestock and aquaculture) accounts for approximately 70% of total freshwater use. Actual population growth and climate change scenarios are substantially increasing levels of water stress globally. Some of the most promising means to improve water use efficiency involve a combination of plant-based dietary choices and reducing food loss and waste. | [181][205][206][207][208][209][210][211] | [184,208,209,210,211,212,213,214] |
| Water use efficiency: micronutrient output per liter consumptive water use. | [212] | [215] | ||
| Blue water scarcity footprint: equivalent amount of water withdrawn from a waterbody at the global average level of stress. | [156][196][213] | [157,199,216] | ||
| Green-blue water (GBW) scarcity index: ratio of GBW availability and water resource requirements for producing a country-specific 3000 kcal/cap/day model diet with 20% of the energy from animal products. | [207][208] | [210,211] | ||
| Blue water scarcity: blue WF amounts in relation to local blue water availability. | [210] | [213] |
Recommendations from wealthier countries such as Europe include reducing the consumption of certain products, such as red meat and sugar, particularly by reducing excessive consumption, and increasing the consumption of fruits, vegetables, nuts and legumes [6][214]. Beyond these relevant global trends, a deeper understanding of the impacts of different production systems would be useful to improve and facilitate the decision-making. Furthermore, these methodologies do not generally consider aspects such as the rate of local/regional food consumption and seasonality, agrobiodiversity and organic/eco-friendly production and consumption [215].
Recommendations from wealthier countries such as Europe include reducing the consumption of certain products, such as red meat and sugar, particularly by reducing excessive consumption, and increasing the consumption of fruits, vegetables, nuts and legumes [6,162]. Beyond these relevant global trends, a deeper understanding of the impacts of different production systems would be useful to improve and facilitate the decision-making. Furthermore, these methodologies do not generally consider aspects such as the rate of local/regional food consumption and seasonality, agrobiodiversity and organic/eco-friendly production and consumption [163].
2.3. Socioeconomic Approach to a Sustainable Healthy Diet
Food security remains the most significant challenge to the development of sustainable and healthy diets. Over 2 billion people, mostly in low- and middle-income countries, do not have regular access to safe, nutritious and sufficient food [216]. However, irregular access is also a challenge for high-income countries, including for 8% of the populations of North America and Europe. Most environmental studies on sustainable diets neglect or minimize socioeconomic factors, rendering their recommendations empirically unfeasible. Furthermore, there is a bias in the geographical focus of studies towards high- and middle-income countries. Of the country-specific studies analyzed, 121 address high-/middle-income countries, while only 26 focus on low-income countries. Dietary choices have macroeconomic and microeconomic implications for both the producer (supply) and consumer (demand) sides. Most studies identify criteria affecting consumer behavior—either affordability and/or acceptability (
Food security remains the most significant challenge to the development of sustainable and healthy diets. Over 2 billion people, mostly in low- and middle-income countries, do not have regular access to safe, nutritious and sufficient food [217]. However, irregular access is also a challenge for high-income countries, including for 8% of the populations of North America and Europe. Most environmental studies on sustainable diets neglect or minimize socioeconomic factors, rendering their recommendations empirically unfeasible. Furthermore, there is a bias in the geographical focus of studies towards high- and middle-income countries. Of the country-specific studies analyzed, 121 address high-/middle-income countries, while only 26 focus on low-income countries. Dietary choices have macroeconomic and microeconomic implications for both the producer (supply) and consumer (demand) sides. Most studies identify criteria affecting consumer behavior—either affordability and/or acceptability (
). A small number of studies consider the distinct constraints that food producers face when adopting the production of healthy food and using methods that minimize environmental damage. Another strand of literature analyzes the value chains that take products from suppliers to the consumer. What is missing from the literature are comprehensive socioeconomic approaches based on criteria that affect supply and demand and the necessary value chains that connect them.
Table 3.
Socioeconomic indicators for a sustainable healthy diet*.
| Criteria |
|---|