Sustainable diets for the future: Can we contribute to reducing greenhouse gas emissions by eating a healthy diet?

Food Literacy at Secondary Schools in Australia

BACKGROUND

Food literacy can encourage adolescents to develop healthy dietary patterns. This study examined home economics teachers' (HET) perspectives of the importance, curriculum, self-efficacy, and food environments regarding food literacy in secondary schools in Australia.

METHODS

A 20-item cross-sectional survey was completed by 205 HETs. The survey focused on the importance of aspects of food literacy, HETs' self-efficacy, and attitudes toward food literacy and schools' food environments. Data were analyzed descriptively, and associations between participants' demographic characteristics and perceptions were investigated by chi-square analyses.

RESULTS

HETs rated aspects of food literacy including preparing and cooking food, knowing about healthy foods and food safety and hygiene practices as very important. They indicated animal welfare, where food comes from, and plan and manage time for food shopping to be the least important aspects of food literacy. HETs reported that students' involvement in food literacy activities resulted in healthier diets and improved food practices, but the schools' food environments are not comprehensively supportive of food literacy.

CONCLUSIONS

HETs report that food literacy is very important for adolescents to learn. The focus is more on microaspects in comparison to macroaspects of food literacy. Schools' food environments are ideally positioned to shape dietary intake of adolescents but their potential is not being realized.

Alignment of Healthy Dietary Patterns and Environmental Sustainability: A Systematic Review

To support food security for current and future generations, there is a need to understand the relation between sustainable diets and the health of a population. In recent years, a number of studies have investigated and compared different dietary patterns to better understand which foods and eating patterns have less of an environmental impact while meeting nutritional needs and promoting health. This systematic review (SR) of population-level dietary patterns and food sustainability extends and updates the SR that was conducted by the 2015 US Dietary Guidelines Advisory Committee, an expert committee commissioned by the federal government to inform dietary guidance as it relates to the committee's original conclusions. In the original SR, 15 studies met the criteria for inclusion; since then, an additional 8 studies have been identified and included. The relations between dietary intake patterns and both health and environmental outcomes were compared across studies, with methodologies that included modeling, life cycle assessment, and land use analysis. Across studies, consistent evidence indicated that a dietary pattern higher in plant-based foods (e.g., vegetables, fruits, legumes, seeds, nuts, whole grains) and lower in animal-based foods (especially red meat), as well as lower in total energy, is both healthier and associated with a lesser impact on the environment. This dietary pattern differs from current average consumption patterns in the United States. Our updated SR confirms and strengthens the conclusions of the original US Dietary Guidelines Advisory Committee SR, which found that adherence to several well-characterized dietary patterns, including vegetarian (with variations) diets, dietary guidelines-related diets, Mediterranean-style diets, the Dietary Approaches to Stop Hypertension (DASH) diet, and other sustainable diet scenarios, promotes greater health and has a less negative impact on the environment than current average dietary intakes.

How low can dietary greenhouse gas emissions be reduced without impairing nutritional adequacy, affordability and acceptability of the diet? A modelling study to guide sustainable food choices

OBJECTIVE

To assess the compatibility between reduction of diet-related greenhouse gas emissions (GHGE) and nutritional adequacy, acceptability and affordability dimensions of diet sustainability.

DESIGN

Dietary intake, nutritional composition, GHGE and prices were combined for 402 foods selected among those most consumed by participants of the Individual National Study on Food Consumption. Linear programming was used to model diets with stepwise GHGE reductions, minimized departure from observed diet and three scenarios of nutritional constraints: none (FREE), on macronutrients (MACRO) and for all nutrient recommendations (ADEQ). Nutritional quality was assessed using the mean adequacy ratio (MAR) and solid energy density (SED).

SETTING

France.

SUBJECTS

Adults (n 1899).

RESULTS

In FREE and MACRO scenarios, imposing up to 30 % GHGE reduction did not affect the MAR, SED and food group pattern of the observed diet, but required substitutions within food groups; higher GHGE reductions decreased diet cost, but also nutritional quality, even with constraints on macronutrients. Imposing all nutritional recommendations (ADEQ) increased the fruits and vegetables quantity, reduced SED and slightly increased diet cost without additional modifications induced by the GHGE constraint up to 30 % reduction; higher GHGE reductions decreased diet cost but required non-trivial dietary shifts from the observed diet. Not all the nutritional recommendations could be met for GHGE reductions ≥70 %.

CONCLUSIONS

Moderate GHGE reductions (≤30 %) were compatible with nutritional adequacy and affordability without adding major food group shifts to those induced by nutritional recommendations. Higher GHGE reductions either impaired nutritional quality, even when macronutrient recommendations were imposed, or required non-trivial dietary shifts compromising acceptability to reach nutritional adequacy.

The climatic impact of food consumption in a representative sample of Irish adults and implications for food and nutrition policy

Objective

To evaluate the greenhouse gas emissions (GHGE) associated with the diet of Irish adults.

Design

GHGE were estimated by applying conversion factors to habitual food consumption data taken from the National Adult Nutrition Survey, which was representative of the population. Descriptive analyses were undertaken for GHGE for the total population, as well as accounting for energy misreporting and across categories of sociodemographic and socio-economic factors and tertiles of emissions.

Setting

Republic of Ireland.

Subjects

Adults aged 18–87 years (n1500).

Results

The GHGE derived from daily dietary intakes was estimated as 6·5 kg of CO2equivalents (CO2eq) per person. Males, younger consumers, those with secondary education and student employment status were associated with significantly higher GHGE. Red meat was the highest contributor to GHGE with 1646 g CO2eq arising from a mean intake of 47 g/d. Dairy and starchy staples were the next largest dietary GHGE sources, with mean daily emissions of 732 g CO2eq and 647 g CO2eq, respectively. The lowest emissions were associated with consumption of vegetables, fruits and legumes/pulses/nuts.

Conclusions

Based on profiling using actual food consumption data, it is evident that one single measure is not sufficient and a range of evidence-based mitigation measures with potential to lower emissions throughout the food chain should be considered. The research contributes towards an improved understanding of the climatic impact of the dietary intakes of Irish adults and can serve to inform a sustainability framework to guide action in food and nutrition policy development.

Consumers' environmental and ethical consciousness and the use of the related food products information: The role of perceived consumer effectiveness

Consumers can be important active contributors to a sustainable society by selecting food choices that are both healthy and produced respecting environmental and socially ethical standards. The current study investigates five consumer behavioural factors - namely, perceived consumer effectiveness (PCE); environmental conscious behaviour; concerns for ethical food production; health conscious lifestyle; and healthy dietary patterns. The key interest of the study lies in exploring the moderating role of PCE - the extent to which the consumer believes that his/her own efforts can make a difference - in these interrelationships. The empirical analysis was conducted through an online survey of food consumers implemented in three markets - the US, the UK and Germany. Findings indicate that for individuals with higher levels of PCE, who are environmental conscious and ethically concerned, information on food labels relating to environmental and social issues represents value by itself. Interestingly, health and nutrition information on food labels was not perceived valuable by consumers with high PCE. The predictive effects of various socio-demographic variables on PCE, consumer environmental and health consciousness are discussed. Cross-cultural differences are also outlined. The results of this research may contribute to the development of environmental policies and communication strategies of the food industry to enhance perceived consumer effectiveness among consumers. Improved PCE, in turn, may catalyze consumers' environmental behaviour and ethical concerns in relation to consumption of food products with environmental and social information.

Registered Dietitian Nutritionists' Perspectives on Integrating Food and Water System Issues into Professional Practice

BACKGROUND

Sustainable agriculture encompasses economic, environmental, and social aspects of the food system. Members of the Academy of Nutrition and Dietetics (Academy) play an important role in promoting sustainable agriculture because they work in areas where they can influence the food purchasing decisions of foodservice operations and the public.

OBJECTIVE

To investigate behavior of registered dietitian nutritionists (RDNs) toward incorporating sustainable agriculture principles into professional practice using the Theory of Planned Behavior.

DESIGN

This cross-sectional study surveyed RDNs nationwide about their perspectives on incorporating sustainable agriculture issues into practice. The survey questions were based on a survey originally administered to Minnesota RDNs during 2002.

PARTICIPANTS AND SETTING

The sample (N=626) was drawn from a randomly selected, national sample of Academy members.

STATISTICAL ANALYSES PERFORMED

Data were analyzed using descriptive statistics, independent t tests, Pearson correlations, and stepwise regression.

RESULTS

The sample was mostly white, female, and the average age was 45.4±12.2 years. Almost half of Academy RDNs (47%) reported incorporating environmental issues into their practice. All four Theory of Planned Behavior variables (intention, attitude, perceived behavior control, and subjective norm) were predictive of behavior to include sustainable agriculture issues into practice. Barriers to incorporating this topic into practice included lack of knowledge, ability, time, and employer support.

CONCLUSIONS

This study found that most of the RDN respondents had heard of sustainable agriculture and nearly half reported including this topic in their professional practice. To integrate this topic into practice more consistently, RDNs need more knowledge, time, and employer support.

Sustainable healthy eating behaviour of young adults: towards a novel methodological approach

Background

Food, nutrition and health policy makers are poised with two pertinent issues more than any other: obesity and climate change. Consumer research has focused primarily on specific areas of sustainable food, such as organic food, local or traditional food, meat substitution and/or reduction. More holistic view of sustainable healthy eating behaviour has received less attention, albeit that more research is emerging in this area.

Methods/design

This study protocol that aims to investigate young consumers’ attitudes and behaviour towards sustainable and healthy eating by applying a multidisciplinary approach, taking into account economical, marketing, public health and environmental related issues. In order to achieve this goal, consumers’ reactions on interactive tailored informational messages about sustainable from social, environmental and economical point of view, as well as healthy eating behaviour in a group of young adults will be investigated using randomized controlled trial.

To undertake the objective, the empirical research is divided into three studies: 1) Qualitative longitudinal research to explore openness to adopting sustainable healthy eating behaviour; 2) Qualitative research with the objective to develop a sustainable healthy eating behaviour index; and 3) Randomised controlled trial to describe consumers’ reactions on interactive tailored messages about sustainable healthy eating in young consumers.

Discussion

To our knowledge, this is the first randomised controlled trial to test the young adults reactions to interactive tailor made messages on sustainable healthy eating using mobile smartphone app. Mobile applications designed to deliver intervention offer new possibilities to influence young adults behaviour in relation to diet and sustainability. Therefore, the study will provide valuable insights into drivers of change towards more environmentally sustainable and healthy eating behaviours.

Trial registration

NCT02776410 registered May 16, 2016.

A Systematic Review of the Measurement of Sustainable Diets

Sustainability has become an integral consideration of the dietary guidelines of many countries in recent decades. However, a lack of clear metrics and a shared approach to measuring the multiple components of sustainable diets has hindered progress toward generating the evidence needed to ensure the credibility of new guidelines. We performed a systematic literature review of empirical research studies on sustainable diets to identify the components of sustainability that were measured and the methods applied to do so. Two independent reviewers systematically searched 30 databases and other sources with the use of a uniform set of search terms and a priori exclusion criteria. In total, 113 empirical studies were included in the final review. Nearly all of the studies were focused on high-income countries. Although there was substantial heterogeneity in the components of sustainability measured, the estimated greenhouse gas emissions (GHGEs) of various dietary patterns were by far most commonly measured (n = 71 studies). Estimating the GHGEs of foods through various stages of production, use, and recycling with the use of the Life Cycle Assessment approach was the most common method applied to measure the environmental impacts of diets (n = 49 studies). Many components of sustainable diets identified in existing conceptual frameworks are disproportionately underrepresented in the empirical literature, as are studies that examine consumer demand for sustainable dietary alternatives. The emphasis in the literature on high-income countries also overlooks the production and dietary alternatives most relevant to low- and middle-income countries. We propose 3 methodological and measurement approaches that would both improve the global relevance of our understanding of sustainable diets and attend more completely to the existing multidimensional, multiscale conceptual framing of sustainable diets.

Beyond Wishful Thinking: Integrating Consumer Preferences in the Assessment of Dietary Recommendations

Convenience, taste, and prices are the main determinants of food choices. Complying with dietary recommendations therefore imposes a “taste cost” on consumers, potentially hindering adoption of those recommendations. The study presents and applies a new methodology, based on economic theory, to quantify this taste cost and assess the health and welfare effects of different dietary recommendations. Then, by comparison of those effects, we identify socially desirable recommendations that are most compatible with consumer preferences (i.e., that best balance health benefits against”taste cost”) and should be prioritized for promotion. The methodology proceeds in three-steps: first, an economic-behavioral model simulates how whole diets would change if consumers complied with dietary recommendations; second, an epidemiological model estimates the number of deaths avoided (DA) due to the dietary change; third, an efficiency analysis weighs the health benefits against the taste and policy costs of each recommendation. The empirical model is calibrated using French data. We find that recommendations to reduce consumption of red meat and soft-drinks, or raise consumption of milk products and fish/seafood impose relatively moderate taste costs. By comparison, recommendations related to F&V consumption and, to a lesser extent, butter/cream/cheese, snacks, and all meats impose larger taste costs on consumers. The F&V recommendation is the costliest for consumers to comply with, but it also reduces diet-related mortality the most, so that a large budget could be allocated to promoting F&V consumption while keeping this policy cost-beneficial. We conclude that promotion of most dietary recommendations improves social welfare. Our framework complements the programming models available in nutrition and public health: those models are best used to identify dietary targets, following which our framework identifies cost-beneficial ways of moving towards those targets.

Essential amino acids: master regulators of nutrition and environmental footprint?

The environmental footprint of animal food production is considered several-fold greater than that of crops cultivation. Therefore, the choice between animal and vegetarian diets may have a relevant environmental impact. In such comparisons however, an often neglected issue is the nutritional value of foods. Previous estimates of nutrients’ environmental footprint had predominantly been based on either food raw weight or caloric content, not in respect to human requirements. Essential amino acids (EAAs) are key parameters in food quality assessment. We re-evaluated here the environmental footprint (expressed both as land use for production and as Green House Gas Emission (GHGE), of some animal and vegetal foods, titrated to provide EAAs amounts in respect to human requirements. Production of high-quality animal proteins, in amounts sufficient to match the Recommended Daily Allowances of all the EAAs, would require a land use and a GHGE approximately equal, greater o smaller (by only ±1-fold), than that necessary to produce vegetal proteins, except for soybeans, that exhibited the smallest footprint. This new analysis downsizes the common concept of a large advantage, in respect to environmental footprint, of crops vs. animal foods production, when human requirements of EAAs are used for reference.

Achieving dietary recommendations and reducing greenhouse gas emissions: modelling diets to minimise the change from current intakes

BACKGROUND

Average population dietary intakes do not reflect the wide diversity of dietary patterns across the population. It is recognised that most people in the UK do not meet dietary recommendations and have diets with a high environmental impact, but changing dietary habits has proved very difficult. The purpose of this study was to investigate the diversity in dietary changes needed to achieve a healthy diet and a healthy diet with lower greenhouse gas emissions (GHGE) (referred to as a sustainable diet) by taking into account each individual's current diet and then minimising the changes they need to make.

METHODS

Linear programming was used to construct two new diets for each adult in the UK National Diet and Nutrition Survey (n = 1491) by minimising the changes to their current intake. Stepwise changes were applied until (i) dietary recommendations were achieved and (ii) dietary recommendations and a GHGE target were met. First, gradual changes (≤50%) were made to the amount of any foods currently eaten. Second, new foods were added to the diet. Third, greater reductions (≤75%) were made to the amount of any food currently eaten and finally, foods were removed from the diet.

RESULTS

One person out of 1491 in the sample met all the dietary requirements based on their reported dietary intake. Only 7.5 and 4.6 % of people achieved a healthy diet and a sustainable diet, respectively, by changing the amount of any food they currently ate by up to 50 %. The majority required changes to the amount of each food eaten plus the addition of new foods. Fewer than 5 % had to remove foods they ate to meet recommendations. Sodium proved the most difficult nutrient recommendation to meet. The healthy diets and sustainable diets produced a 15 and 27 % reduction in greenhouse gas emissions respectively.

CONCLUSIONS

Since healthy diets alone do not produce substantial reductions in greenhouse gas emissions, dietary guidelines need to include recommendations for environmental sustainability. Minimising the shift from current dietary intakes is likely to make dietary change more realistic and achievable.

How to Build a Standardized Country-Specific Environmental Food Database for Nutritional Epidemiology Studies

There is a lack of standardized country-specific environmental data to combine with nutritional and dietary data for assessing the environmental impact of individual diets in epidemiology surveys, which are consequently reliant on environmental food datasets based on values retrieved from a heterogeneous literature. The aim of this study was to compare and assess the relative strengths and limits of a database of food greenhouse gas emissions (GHGE) values estimated with a hybrid method combining input/output and LCA approaches, with a dataset of GHGE values retrieved from the literature. France is the geographical perimeter considered in this study, but the methodology could be applied to other countries. The GHGE of 402 foodstuffs, representative of French diet, were estimated using the hybrid method. In parallel, the GHGE of individual foods were collected from existing literature. Median per-food-category GHGE values from the hybrid method and the reviewed literature were found to correlate strongly (Spearman correlation was 0.83), showing similar rankings of food categories. Median values were significantly different for only 5 (out of 29) food categories, including the ruminant meats category for which the hybrid method gave lower estimates than those from existing literature. Analysis also revealed that literature values came from heterogeneous studies that were not always sourced and that were conducted under different LCA modeling hypotheses. In contrast, the hybrid method helps build reliably-sourced, representative national standards for product-based datasets. We anticipate this hybrid method to be a starting point for better environmental impact assessments of diets.

Excessive red and processed meat intake: relations with health and environment in Brazil

The aims of the present study were to verify the proportion of population that consumed more red and processed meat than the World Cancer Research Fund (WCRF) dietary recommendation, to estimate the environmental impact of beef intake and the possible reduction of greenhouse gas emissions if the dietary recommendation was followed. We used the largest, cross-sectional, population-based survey entitled the National Dietary Survey (34 003 participants aged 10–104 years). The usual meat intake was obtained by two food records completed on 2 non-consecutive days. The usual intake was estimated by the multiple source method. The environmental impact was analysed according to estimates of CO2 equivalent emissions from beef intake as a proxy for beef production in Brazil. The red and processed meat intake mean was 88 g/d. More than 80 % of the population consumed more red and processed meat than the WCRF recommendation. Beef was the type of meat most consumed, accounting to almost 50 %. Each person contributed 1005 kg of CO2 equivalents from beef intake in 2008, the same quantity of CO2 produced if a car travelled a distance between the extreme north and south of Brazil (5370 km). The entire Brazilian population contributed more than 191 million tons of CO2 equivalents, which could have been reduced to more than 131 million tons if the dietary recommendation was followed. The present study shows that the magnitude of the excessive red and processed meat intake in Brazil can impact on health and the environment, pointing to the urgency of promoting a sustainable diet.

Protein Considerations for Optimising Skeletal Muscle Mass in Healthy Young and Older Adults

Skeletal muscle is critical for human health. Protein feeding, alongside resistance exercise, is a potent stimulus for muscle protein synthesis (MPS) and is a key factor that regulates skeletal muscle mass (SMM). The main purpose of this narrative review was to evaluate the latest evidence for optimising the amino acid or protein source, dose, timing, pattern and macronutrient coingestion for increasing or preserving SMM in healthy young and healthy older adults. We used a systematic search strategy of PubMed and Web of Science to retrieve all articles related to this review objective. In summary, our findings support the notion that protein guidelines for increasing or preserving SMM are more complex than simply recommending a total daily amount of protein. Instead, multifactorial interactions between protein source, dose, timing, pattern and macronutrient coingestion, alongside exercise, influence the stimulation of MPS, and thus should be considered in the context of protein recommendations for regulating SMM. To conclude, on the basis of currently available scientific literature, protein recommendations for optimising SMM should be tailored to the population or context of interest, with consideration given to age and resting/post resistance exercise conditions.

Towards a sustainable diet combining economic, environmental and nutritional objectives

Foods consumed and dietary patterns are strong determinants of health status. Diet and nutrition have a key role in health promotion and maintenance during the entire lifetime, but what we choose to eat and drink greatly affects the environmental impact on ecosystems as well as monetary resources. Some studies suggest that a healthy diet with a low environmental impact is not necessarily more expensive. This paper aims to identify a healthy, greener and cheaper diet based on current consumption patterns. Dietary information was collected from 104 young adults in the last year of high school in Parma (Italy). Diet was monitored with 7-day dietary records. Subsequently, food items were decoded to obtain nutritional, economic and environmental impact data. An optimization tool based on mathematical programming (Multi-Objective Linear Programming) was used to identify sustainable diet. Three different 7-day diets were identified, based on nutrition recommendations for the healthy Italian adult population, characterized by different targets and optimizing different impacts: first the diet at the lowest cost (Minimum Cost Diet - MCD), then the Environmentally Sustainable Diet (ESD) obtained by minimizing the three environmental indicators (CO2e emissions, H2O consumption and amount of land to regenerate the resources - m(2)). Finally, the Sustainable Diet (SD) was identified by integrating environmental and economic sustainability objectives. Lastly, suggestions and recommendations for communication campaigns and other interventions to achieve sustainable diet are suggested.

Dairy in a sustainable diet: a question of balance

The demand for dairy products is growing rapidly, especially in emerging markets. Dairy products are nutrient rich and, therefore, an important food group for ensuring nutrient security in the future. In many countries, dairy contributes significantly to nutrient intake. Meta-analyses have shown that consumption of dairy may reduce the risk of chronic diseases and thereby lower healthcare costs. Milk production and processing contribute to greenhouse gas emissions, estimated at 2.7% (cradle-to-retail) of the world's total. Evaluating the position of dairy in the diet should take into account the impact of both nutritional and environmental factors. Local conditions are also important; in many parts of the world, the cow is an efficient converter of human-inedible resources into nutrient-dense food. Increased productivity of cows is a decisive factor in realizing sufficient milk production with optimal resource efficiency and minimal greenhouse gas emission. Models that optimize total diets, rather than individual food products, for their nutritional and environmental impact are the preferred approach for developing realistic alternative consumption strategies.

Diet-related greenhouse gas emissions assessed by a food frequency questionnaire and validated using 7-day weighed food records

BACKGROUND

The current food system generates about 25 % of total greenhouse gas emissions (GHGE), including deforestation, and thereby substantially contributes to the warming of the earth's surface. To understand the association between food and nutrient intake and GHGE, we therefore need valid methods to assess diet-related GHGE in observational studies.

METHODS

Life cycle assessment (LCA) studies assess the environmental impact of different food items. We linked LCA data expressed as kg carbon dioxide equivalents (CO2e) per kg food product to data on food intake assessed by the food frequency questionnaire (FFQ) Meal-Q and validated it against a 7-day weighed food record (WFR). 166 male and female volunteers aged 20-63 years completed Meal-Q and the WFR, and their food intake was linked to LCA data.

RESULTS

The mean GHGE assessed with Meal-Q was 3.76 kg CO2e per day and person, whereas it was 5.04 kg CO2e using the WFR. The energy-adjusted and deattenuated Pearson and Spearman correlation coefficients were 0.68 and 0.70, respectively. Moreover, compared to the WFR, Meal-Q provided a good ranking ability, with 90 % of the participants classified into the same or adjacent quartile according to their daily average CO2e. The Bland-Altman plot showed an acceptable level of agreement between the two methods and the reproducibility of Meal-Q was high.

CONCLUSIONS

This is the first study validating the assessment of diet-related GHGE by a questionnaire. The results suggest that Meal-Q is a useful tool for studying the link between food habits and CO2e in future epidemiological studies.

Simulating the impact on health of internalising the cost of carbon in food prices combined with a tax on sugar-sweetened beverages

Background

Rising greenhouse gas emissions (GHGEs) have implications for health and up to 30 % of emissions globally are thought to arise from agriculture. Synergies exist between diets low in GHGEs and health however some foods have the opposite relationship, such as sugar production being a relatively low source of GHGEs. In order to address this and to further characterise a healthy sustainable diet, we model the effect on UK non-communicable disease mortality and GHGEs of internalising the social cost of carbon into the price of food alongside a 20 % tax on sugar sweetened beverages (SSBs).

Methods

Developing previously published work, we simulate four tax scenarios: (A) a GHGEs tax of £2.86/tonne of CO2 equivalents (tCO2e)/100 g product on all products with emissions greater than the mean across all food groups (0.36 kgCO2e/100 g); (B) scenario A but with subsidies on foods with emissions lower than 0.36 kgCO2e/100 g such that the effect is revenue neutral; (C) scenario A but with a 20 % sales tax on SSBs; (D) scenario B but with a 20 % sales tax on SSBs. An almost ideal demand system is used to estimate price elasticities and a comparative risk assessment model is used to estimate changes to non-communicable disease mortality.

Results

We estimate that scenario A would lead to 300 deaths delayed or averted, 18,900 ktCO2e fewer GHGEs, and £3.0 billion tax revenue; scenario B, 90 deaths delayed or averted and 17,100 ktCO2e fewer GHGEs; scenario C, 1,200 deaths delayed or averted, 18,500 ktCO2e fewer GHGEs, and £3.4 billion revenue; and scenario D, 2,000 deaths delayed or averted and 16,500 ktCO2e fewer GHGEs. Deaths averted are mainly due to increased fibre and reduced fat consumption; a SSB tax reduces SSB and sugar consumption.

Conclusions

Incorporating the social cost of carbon into the price of food has the potential to improve health, reduce GHGEs, and raise revenue. The simple addition of a tax on SSBs can mitigate negative health consequences arising from sugar being low in GHGEs. Further conflicts remain, including increased consumption of unhealthy foods such as cakes and nutrients such as salt.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2723-8) contains supplementary material, which is available to authorized users.

Eating like there's no tomorrow: Public awareness of the environmental impact of food and reluctance to eat less meat as part of a sustainable diet

Reducing meat consumption is central to many of the scientific debates on healthy, sustainable diets because of the high environmental impact of meat production. Missing from these debates are the public perspectives about eating less meat and consideration of cultural and social values associated with meat. The aim of this study was to explore public awareness of the environmental impact of food and their willingness to reduce meat consumption. Twelve focus groups and four individual interviews were conducted with adults from a range of socio-economic groups living in both rural and urban settings in Scotland. Public understanding of the link between food, environment and climate change was explored, with a focus on meat and attitudes towards reducing meat consumption. Data were transcribed and analysed thematically. Three dominant themes emerged: a lack of awareness of the association between meat consumption and climate change, perceptions of personal meat consumption playing a minimal role in the global context of climate change, and resistance to the idea of reducing personal meat consumption. People associated eating meat with pleasure, and described social, personal and cultural values around eating meat. Some people felt they did not need to eat less meat because they had already reduced their consumption or that they only ate small quantities. Scepticism of scientific evidence linking meat and climate change was common. Changing non-food related behaviours was viewed as more acceptable and a greater priority for climate change mitigation. The study highlights the role meat plays in the diet for many people, beyond nutritional needs. If healthy, sustainable dietary habits are to be achieved, cultural, social and personal values around eating meat must be integrated into the development of future dietary recommendations.

How may a shift towards a more sustainable food consumption pattern affect nutrient intakes of Dutch children?

Objective

Food has a considerable environmental impact. Diets with less meat and dairy reduce environmental impact but may pose nutritional challenges for children. The current modelling study investigates the impact of diets with less or no meat and dairy products on nutrient intakes.

Design

Energy and nutrient intakes were assessed for observed consumption patterns (reference) and two replacement scenarios with data from the Dutch National Food Consumption Survey – Young Children (2005–2006). In the replacement scenarios, 30 % or 100 % of the consumed dairy and meat (in grams) was replaced by plant-derived foods with similar use.

Setting

The Netherlands.

Subjects

Children (n 1279) aged 2–6 years.

Results

Partial and full replacement of meat and dairy foods by plant-derived foods reduced SFA intake by 9 % and 26 %, respectively, while fibre intake was 8 % and 29 % higher. With partial replacement, micronutrient intakes were similar, except for lower vitamin B12 intake. After full meat and dairy replacement, mean intakes of Ca, Zn and thiamin decreased by 5–13 %, and vitamin B12 intake by 49 %, while total intake of Fe was higher but of lower bioavailability. With full replacement, the proportion of girls aged 4–6 years with intakes below recommendations was 15 % for thiamin, 10 % for vitamin B12 and 6 % for Zn.

Conclusions

Partial replacement of meat and dairy by plant-derived foods is beneficial for children’s health by lowering SFA intake, increasing fibre content and maintaining similar micronutrient intakes. When full replacements are made, attention is recommended to ensure adequate thiamin, vitamin B12 and Zn intakes.

Formulating policy activities to promote healthy and sustainable diets

Objective

To develop a policy formulation tool for strategically informing food and nutrition policy activities to promote healthy and sustainable diets (HSD).

Design

A policy formulation tool consisting of two complementary components was developed. First, a conceptual framework of the environment–public health nutrition relationship was constructed to characterise and conceptualise the food system problem. Second, an ‘Orders of Food Systems Change’ schema drawing on systems dynamics thinking was developed to identify, assess and propose policy options to redesign food systems.

Setting

Food and nutrition policy activities to promote HSD have been politicised, fragmented and lacking a coherent conceptual and strategic focus to tackle complex food system challenges.

Results

The tool’s conceptual framework component comprises three integrated dimensions: (i) a structure built around the environment and public health nutrition relationship that is mediated via the food system; (ii) internal mechanisms that operate through system dynamics; and (iii) external interactions that frame its nature and a scope within ecological parameters. The accompanying schema is structured around three orders of change distinguished by contrasting ideological perspectives on the type and extent of change needed to ‘solve’ the HSD problem.

Conclusions

The conceptual framework’s systems analysis of the environment–public health nutrition relationship sets out the food system challenges for HSD. The schema helps account for political realities in policy making and is a key link to operationalise the framework’s concepts to actions aimed at redesigning food systems. In combination they provide a policy formulation tool to strategically inform policy activities to redesign food systems and promote HSD.

A Novel Dietary Assessment Method to Measure a Healthy and Sustainable Diet Using the Mobile Food Record: Protocol and Methodology

The world-wide rise in obesity parallels growing concerns of global warming and depleting natural resources. These issues are often considered separately but there may be considerable benefit to raising awareness of the impact of dietary behaviours and practices on the food supply. Australians have diets inconsistent with recommendations, typically low in fruit and vegetables and high in energy-dense nutrient-poor foods and beverages (EDNP). These EDNP foods are often highly processed and packaged, negatively influencing both health and the environment. This paper describes a proposed dietary assessment method to measure healthy and sustainable dietary behaviours using 4-days of food and beverage images from the mobile food record (mFR) application. The mFR images will be assessed for serves of fruit and vegetables (including seasonality), dairy, eggs and red meat, poultry and fish, ultra-processed EDNP foods, individually packaged foods, and plate waste. A prediction model for a Healthy and Sustainable Diet Index will be developed and tested for validity and reliability. The use of the mFR to assess adherence to a healthy and sustainable diet is a novel and innovative approach to dietary assessment and will have application in population monitoring, guiding intervention development, educating consumers, health professionals and policy makers, and influencing dietary recommendations.

Greater accordance with the Dietary Approaches to Stop Hypertension dietary pattern is associated with lower diet-related greenhouse gas production but higher dietary costs in the United Kingdom

BACKGROUND

The Dietary Approaches to Stop Hypertension (DASH) diet is a proven way to prevent and control hypertension and other chronic disease. Because the DASH diet emphasizes plant-based foods, including vegetables and grains, adhering to this diet might also bring about environmental benefits, including lower associated production of greenhouse gases (GHGs).

OBJECTIVE

The objective was to examine the interrelation between dietary accordance with the DASH diet and associated GHGs. A secondary aim was to examine the retail cost of diets by level of DASH accordance.

DESIGN

In this cross-sectional study of adults aged 39-79 y from the European Prospective Investigation into Cancer and Nutrition-Norfolk, United Kingdom cohort (n = 24,293), dietary intakes estimated from food-frequency questionnaires were analyzed for their accordance with the 8 DASH food and nutrient-based targets. Associations between DASH accordance, GHGs, and dietary costs were evaluated in regression analyses. Dietary GHGs were estimated with United Kingdom-specific data on carbon dioxide equivalents associated with commodities and foods. Dietary costs were estimated by using national food prices from a United Kingdom-based supermarket comparison website.

RESULTS

Greater accordance with the DASH dietary targets was associated with lower GHGs. Diets in the highest quintile of accordance had a GHG impact of 5.60 compared with 6.71 kg carbon dioxide equivalents/d for least-accordant diets (P < 0.0001). Among the DASH food groups, GHGs were most strongly and positively associated with meat consumption and negatively with whole-grain consumption. In addition, higher accordance with the DASH diet was associated with higher dietary costs, with the mean cost of diets in the top quintile of DASH scores 18% higher than that of diets in the lowest quintile (P < 0.0001).

CONCLUSIONS

Promoting wider uptake of the DASH diet in the United Kingdom may improve population health and reduce diet-related GHGs. However, to make the DASH diet more accessible, food affordability, particularly for lower income groups, will have to be addressed.

Health effects of adopting low greenhouse gas emission diets in the UK

OBJECTIVE

Dietary changes which improve health are also likely to be beneficial for the environment by reducing emissions of greenhouse gases (GHG). However, previous analyses have not accounted for the potential acceptability of low GHG diets to the general public. This study attempted to quantify the health effects associated with adopting low GHG emission diets in the UK.

DESIGN

Epidemiological modelling study.

SETTING

UK.

PARTICIPANTS

UK population.

INTERVENTION

Adoption of diets optimised to achieve the WHO nutritional recommendations and reduce GHG emissions while remaining as close as possible to existing dietary patterns.

MAIN OUTCOME

Changes in years of life lost due to coronary heart disease, stroke, several cancers and type II diabetes, quantified using life tables.

RESULTS

If the average UK dietary intake were optimised to comply with the WHO recommendations, we estimate an incidental reduction of 17% in GHG emissions. Such a dietary pattern would be broadly similar to the current UK average. Our model suggests that it would save almost 7 million years of life lost prematurely in the UK over the next 30 years and increase average life expectancy by over 8 months. Diets that result in additional GHG emission reductions could achieve further net health benefits. For emission reductions greater than 40%, improvements in some health outcomes may decrease and acceptability will diminish.

CONCLUSIONS

There are large potential benefits to health from adopting diets with lower associated GHG emissions in the UK. Most of these benefits can be achieved without drastic changes to existing dietary patterns. However, to reduce emissions by more than 40%, major dietary changes that limit both acceptability and the benefits to health are required.

The Global Nutrition Report 2014: actions and accountability to accelerate the world's progress on nutrition

In 2013, the Nutrition for Growth Summit called for a Global Nutrition Report (GNR) to strengthen accountability in nutrition so that progress in reducing malnutrition could be accelerated. This article summarizes the results of the first GNR. By focusing on undernutrition and overweight, the GNR puts malnutrition in a new light. Nearly every country in the world is affected by malnutrition, and multiple malnutrition burdens are the "new normal." Unfortunately, the world is off track to meet the 2025 World Health Assembly (WHA) targets for nutrition. Many countries are, however, making good progress on WHA indicators, providing inspiration and guidance for others. Beyond the WHA goals, nutrition needs to be more strongly represented in the Sustainable Development Goal (SDG) framework. At present, it is only explicitly mentioned in 1 of 169 SDG targets despite the many contributions improved nutritional status will make to their attainment. To achieve improvements in nutrition status, it is vital to scale up nutrition programs. We identify bottlenecks in the scale-up of nutrition-specific and nutrition-sensitive approaches and highlight actions to accelerate coverage and reach. Holding stakeholders to account for delivery on nutrition actions requires a well-functioning accountability infrastructure, which is lacking in nutrition. New accountability mechanisms need piloting and evaluation, financial resource flows to nutrition need to be made explicit, nutrition spending targets should be established, and some key data gaps need to be filled. For example, many UN member states cannot report on their WHA progress and those that can often rely on data >5 y old. The world can accelerate malnutrition reduction substantially, but this will require stronger accountability mechanisms to hold all stakeholders to account.

Which functional unit to identify sustainable foods?

Objective

In life-cycle assessment, the functional unit defines the unit for calculation of environmental indicators. The objective of the present study was to assess the influence of two functional units, 100 g and 100 kcal (420 kJ), on the associations between three dimensions for identifying sustainable foods, namely environmental impact (via greenhouse gas emissions (GHGE)), nutritional quality (using two distinct nutrient profiling systems) and price.

Design

GHGE and price data were collected for individual foods, and were each expressed per 100 g and per 100 kcal. Two nutrient profiling models, SAIN,LIM and UK Ofcom, were used to assess foods’ nutritional quality. Spearman correlations were used to assess associations between variables. Sustainable foods were identified as those having more favourable values for all three dimensions.

Setting

The French Individual and National Dietary Survey (INCA2), 2006–2007.

Subjects

Three hundred and seventy-three foods highly consumed in INCA2, covering 65 % of total energy intake of adult participants.

Results

When GHGE and price were expressed per 100 g, low-GHGE foods had a lower price and higher SAIN,LIM and Ofcom scores (r=0·59, −0·34 and −0·43, respectively), suggesting a compatibility between the three dimensions; 101 and 100 sustainable foods were identified with SAIN,LIM and Ofcom, respectively. When GHGE and price were expressed per 100 kcal, low-GHGE foods had a lower price but also lower SAIN,LIM and Ofcom scores (r=0·67, 0·51 and 0·47, respectively), suggesting that more environment-friendly foods were less expensive but also less healthy; thirty-four sustainable foods were identified with both SAIN,LIM and Ofcom.

Conclusions

The choice of functional unit strongly influenced the compatibility between the sustainability dimensions and the identification of sustainable foods.

Seasonality and dietary requirements: will eating seasonal food contribute to health and environmental sustainability?

Eating more seasonal food is one proposal for moving towards more sustainable consumption patterns, based on the assumption that it could reduce the environmental impact of the diet. The aim of the present paper is to consider the implications of eating seasonal food on the different elements of sustainability (i.e. health, economics, society), not just the environment. Seasonality can be defined as either globally seasonal (i.e. produced in the natural production season but consumed anywhere in the world) or locally seasonal (i.e. produced in the natural production season and consumed within the same climatic zone). The environmental, health, economic and societal impact varies by the definition used. Global seasonality has the nutritional benefit of providing a more varied and consistent supply of fresh produce year round, but this increases demand for foods that in turn can have a high environmental cost in the country of production (e.g. water stress, land use change with loss of biodiversity). Greenhouse gas emissions of globally seasonal food are not necessarily higher than food produced locally as it depends more on the production system used than transportation. Eating more seasonal food, however, is only one element of a sustainable diet and should not overshadow some of the potentially more difficult dietary behaviours to change that could have greater environmental and health benefits (e.g. reducing overconsumption or meat consumption). For future guidelines for sustainable diets to be realistic they will need to take into account modern lifestyles, cultural and social expectations in the current food environment.

What current literature tells us about sustainable diets: emerging research linking dietary patterns, environmental sustainability, and economics

The concept of sustainable diets, although not new, is gaining increased attention across the globe, especially in relation to projected population growth and growing concerns about climate change. As defined by the FAO (Proceedings of the International Scientific Symposium, Biodiversity and Sustainable Diets 2010; FAO 2012), "Sustainable diets are those diets with low environmental impacts which contribute to food and nutrition security and to healthy life for present and future generations." Consistent and credible science that brings together agriculture, food systems, nutrition, public health, environment, economics, culture, and trade is needed to identify synergies and trade-offs and to inform guidance on vital elements of healthy, sustainable diets. The aim of this article is to review the emerging research on environmental and related economic impacts of dietary patterns, including habitual eating patterns, nutritionally balanced diets, and a variety of different dietary scenarios. Approaches to research designs, methodologies, and data sources are compared and contrasted to identify research gaps and future research needs. To date, it is difficult to assimilate all of the disparate approaches, and more concerted efforts for multidisciplinary studies are needed.

Energy and nutrient density of foods in relation to their carbon footprint

BACKGROUND

A carbon footprint is the sum of greenhouse gas emissions (GHGEs) associated with food production, processing, transporting, and retailing.

OBJECTIVE

We examined the relation between the energy and nutrient content of foods and associated GHGEs as expressed as g CO2 equivalents.

DESIGN

GHGE values, which were calculated and provided by a French supermarket chain, were merged with the Composition Nutritionnelle des Aliments (French food-composition table) nutrient-composition data for 483 foods and beverages from the French Agency for Food, Environmental and Occupational Health and Safety. Foods were aggregated into 34 food categories and 5 major food groups as follows: meat and meat products, milk and dairy products, frozen and processed fruit and vegetables, grains, and sweets. Energy density was expressed as kcal/100 g. Nutrient density was determined by using 2 alternative nutrient-density scores, each based on the sum of the percentage of daily values for 6 or 15 nutrients, respectively. The energy and nutrient densities of foods were linked to log-transformed GHGE values expressed per 100 g or 100 kcal.

RESULTS

Grains and sweets had lowest GHGEs (per 100 g and 100 kcal) but had high energy density and a low nutrient content. The more-nutrient-dense animal products, including meat and dairy, had higher GHGE values per 100 g but much lower values per 100 kcal. In general, a higher nutrient density of foods was associated with higher GHGEs per 100 kcal, although the slopes of fitted lines varied for meat and dairy compared with fats and sweets.

CONCLUSIONS

Considerations of the environmental impact of foods need to be linked to concerns about nutrient density and health. The point at which the higher carbon footprint of some nutrient-dense foods is offset by their higher nutritional value is a priority area for additional research.

Economic assessment of nutritional recommendations

The effect of consumers' compliance with nutritional recommendations is uncertain because of potentially complex substitutions. To lift this uncertainty, we adapt a model of consumer behaviour under rationing to the case of linear nutritional constraints. Dietary adjustments are derived from information on consumer preferences, consumption levels, and nutritional contents of foods. A calibration exercise simulates, for different income groups, how the French diet would respond to various nutrition recommendations, and those behavioural adjustments are translated into health outcomes through the DIETRON epidemiological model. This allows for the ex-ante comparison of the efficiency, equity and health effects of ten nutritional recommendations. Although most recommendations impose significant taste costs on consumers, they are highly cost-effective, with the recommendations targeting salt, saturated fat, and fruits and vegetables (F&V) ranking highest in terms of efficiency. Most recommendations are also economically progressive, with the exception of that targeting F&V.

Greenhouse gas emission of diets in the Netherlands and associations with food, energy and macronutrient intakes

OBJECTIVE

To evaluate the greenhouse gas emission (GHGE) of diets in Dutch girls, boys, women and men and to explore associations with diet composition.

DESIGN

Descriptive analyses for the total population as well as stratified for gender, age and dietary environmental load.

SETTING

The Netherlands.

SUBJECTS

Dutch children and adults aged 7-69 years (n 3818).

RESULTS

The GHGE of daily diets was on average 3·2 kg CO2-equivalents (CO2e) for girls, 3·6 kg CO2e for boys, 3·7 kg CO2e for women and 4·8 kg CO2e for men. Meat and cheese contributed about 40 % and drinks (including milk and alcoholic drinks) 20 % to daily GHGE. Considerable differences in environmental loads of diets existed within age and gender groups. Persons with higher-GHGE diets consumed more (in quantity of foods and especially drinks) than their counterparts of a similar sex and age with low-GHGE diets. Major differences between high- and low-GHGE diets were in meat, cheese and dairy consumption as well as in soft drinks (girls, boys and women) and alcoholic drinks (men). Of those, differences in meat consumption determined the differences in GHGE most. Diets with higher GHGE were associated with higher saturated fat intake and lower fibre intake

CONCLUSIONS

GHGE of daily diets in the Netherlands is between 3 and 5 kg CO2e, with considerable differences between individuals. Meat, dairy and drinks contribute most to GHGE. The insights of the study may be used in developing (age- and gender-specific) food-based dietary guidelines that take into account both health and sustainability aspects.

Comparing the water, energy, pesticide and fertilizer usage for the production of foods consumed by different dietary types in California

Objective

To compare the use of water, energy, pesticides and fertilizer to produce commodities for two dietary patterns that vary in the content of plant and animal products.

Design

A unique analysis using ‘real-world’ data was performed, in contrast to previous analyses which applied simulated data. Consumption data from the Adventist Health Study were used to identify two dietary patterns with a markedly different consumption of several plant and animal products. State agricultural data were collected and applied to commodity production statistics. Indices were created to allow a comparison of the resource requirements for each dietary pattern.

Setting

California, USA.

Subjects

None.

Results

The diet containing more animal products required an additional 10 252 litres of water, 9910 kJ of energy, 186 g of fertilizer and 6 g of pesticides per week in comparison to the diet containing less animal products. The greatest contribution to the difference came from the consumption of animal products, particularly beef.

Conclusions

Consuming a more plant-based diet could to an extent alleviate the negative environmental impacts related to food production. As a method to feed ourselves more sustainably, behavioural adjustments appear to be a very important tool.

Agricultural biodiversity, social-ecological systems and sustainable diets

The stark observation of the co-existence of undernourishment, nutrient deficiencies and overweight and obesity, the triple burden of malnutrition, is inviting us to reconsider health and nutrition as the primary goal and final endpoint of food systems. Agriculture and the food industry have made remarkable advances in the past decades. However, their development has not entirely fulfilled health and nutritional needs, and moreover, they have generated substantial collateral losses in agricultural biodiversity. Simultaneously, several regions are experiencing unprecedented weather events caused by climate change and habitat depletion, in turn putting at risk global food and nutrition security. This coincidence of food crises with increasing environmental degradation suggests an urgent need for novel analyses and new paradigms. The sustainable diets concept proposes a research and policy agenda that strives towards a sustainable use of human and natural resources for food and nutrition security, highlighting the preeminent role of consumers in defining sustainable options and the importance of biodiversity in nutrition. Food systems act as complex social-ecological systems, involving multiple interactions between human and natural components. Nutritional patterns and environment structure are interconnected in a mutual dynamic of changes. The systemic nature of these interactions calls for multidimensional approaches and integrated assessment and simulation tools to guide change. This paper proposes a review and conceptual modelling framework that articulate the synergies and tradeoffs between dietary diversity, widely recognised as key for healthy diets, and agricultural biodiversity and associated ecosystem functions, crucial resilience factors to climate and global changes.

Understanding sustainable diets: a descriptive analysis of the determinants and processes that influence diets and their impact on health, food security, and environmental sustainability

The confluence of population, economic development, and environmental pressures resulting from increased globalization and industrialization reveal an increasingly resource-constrained world in which predictions point to the need to do more with less and in a "better" way. The concept of sustainable diets presents an opportunity to successfully advance commitments to sustainable development and the elimination of poverty, food and nutrition insecurity, and poor health outcomes. This study examines the determinants of sustainable diets, offers a descriptive analysis of these areas, and presents a causal model and framework from which to build. The major determinants of sustainable diets fall into 5 categories: 1) agriculture, 2) health, 3) sociocultural, 4) environmental, and 5) socioeconomic. When factors or processes are changed in 1 determinant category, such changes affect other determinant categories and, in turn, the level of "sustainability" of a diet. The complex web of determinants of sustainable diets makes it challenging for policymakers to understand the benefits and considerations for promoting, processing, and consuming such diets. To advance this work, better measurements and indicators must be developed to assess the impact of the various determinants on the sustainability of a diet and the tradeoffs associated with any recommendations aimed at increasing the sustainability of our food system.

Climate change mitigation and health effects of varied dietary patterns in real-life settings throughout North America

BACKGROUND

Greenhouse gas emissions (GHGEs) are a major consequence of our dietary choices. Assessments of plant-based compared with meat-based diets are emerging at the intersection of public health, environment, and nutrition.

OBJECTIVES

The objective was to compare the GHGEs associated with dietary patterns consumed in a large population across North America and to independently assess mortality according to dietary patterns in the same population.

DESIGN

Data from the Adventist Health Study 2 (AHS-2) were used to characterize the differential environmental and health impacts of the following 3 dietary patterns, which varied in the quantity of animal and plant foods: vegetarian, semivegetarian, and nonvegetarian. The GHGE intensities of 210 foods were calculated through life-cycle assessments and by using published data. The all-cause mortality rates and all-cause mortality HRs for the AHS-2 subjects were adjusted for a range of lifestyle and sociodemographic factors and estimated according to dietary pattern.

RESULTS

With the use of the nonvegetarian diet as a reference, the mean reductions in GHGEs for semivegetarian and vegetarian diets were 22% and 29%, respectively. The mortality rates for nonvegetarians, semivegetarians, and vegetarians were 6.66, 5.53, and 5.56 deaths per 1000 person-years, respectively. The differences were significant. Compared with nonvegetarians, mortality HRs were lower for semivegetarians (0.86) and vegetarians (0.91).

CONCLUSIONS

Moderate differences in the caloric intake of meat products provided nontrivial reductions in GHGEs and improved health outcomes, as shown through the mortality analyses. However, this does not mean that diets lower in GHGEs are healthy.

Sustainability of plant-based diets: back to the future

Plant-based diets in comparison to diets rich in animal products are more sustainable because they use many fewer natural resources and are less taxing on the environment. Given the global population explosion and increase in wealth, there is an increased demand for foods of animal origin. Environmental data are rapidly accumulating on the unsustainability of current worldwide food consumption practices that are high in meat and dairy products. Natural nonrenewable resources are becoming scarce, and environmental degradation is rapidly increasing. At the current trends of food consumption and environmental changes, food security and food sustainability are on a collision course. Changing course (to avoid the collision) will require extreme downward shifts in meat and dairy consumption by large segments of the world's population. Other approaches such as food waste reduction and precision agriculture and/or other technological advances have to be simultaneously pursued; however, they are insufficient to make the global food system sustainable. For millennia, meatless diets have been advocated on the basis of values, and large segments of the world population have thrived on plant-based diets. "Going back" to plant-based diets worldwide seems to be a reasonable alternative for a sustainable future. Policies in favor of the global adoption of plant-based diets will simultaneously optimize the food supply, health, environmental, and social justice outcomes for the world's population. Implementing such nutrition policy is perhaps one of the most rational and moral paths for a sustainable future of the human race and other living creatures of the biosphere that we share.

Vegetarian nutrition: past, present, future

Early human food cultures were plant-based. Major religions such as Hinduism and Buddhism have recommended a vegetarian way of life since their conception. The recorded history of vegetarian nutrition started in the sixth century bc by followers of the Orphic mysteries. The Greek philosopher Pythagoras is considered the father of ethical vegetarianism. The Pythagorean way of life was followed by a number of important personalities and influenced vegetarian nutrition until the 19th century. In Europe, vegetarian nutrition more or less disappeared during the Middle Ages. In the Renaissance era and in the Age of Enlightenment, various personalities practiced vegetarianism. The first vegetarian society was started in England in 1847. The International Vegetarian Society was founded in 1908 and the first vegan society began in 1944. Prominent vegetarians during this time included Sylvester Graham, John Harvey Kellogg, and Maximilian Bircher-Benner. A paradigm shift occurred at the turn of the 21st century. The former prejudices that vegetarianism leads to malnutrition were replaced by scientific evidence showing that vegetarian nutrition reduces the risk of most contemporary diseases. Today, vegetarian nutrition has a growing international following and is increasingly accepted. The main reasons for this trend are health concerns and ethical, ecologic, and social issues. The future of vegetarian nutrition is promising because sustainable nutrition is crucial for the well-being of humankind. An increasing number of people do not want animals to suffer nor do they want climate change; they want to avoid preventable diseases and to secure a livable future for generations to come.

Are the dietary guidelines for meat, fat, fruit and vegetable consumption appropriate for environmental sustainability? A review of the literature

This paper reviews the current literature around the environmental impacts of dietary recommendations. The focus of the review is on collating evidence relating to environmental impacts of the dietary advice found in the World Health Organisation guidelines, and environmental impact literature: reducing the consumption of fat, reducing the consumption of meat-based protein and animal-based foods, and increasing the consumption of fruit and vegetables. The environmental impact of reducing dietary fat intake is unclear, although reducing consumption of the food category of edible fats and oils appears to have little impact. However most, but not all, studies support environmental benefits of a reduced consumption of animal-based foods and increased consumption of fruit and vegetables. In general, it appears that adhering to dietary guidelines reduces impact on the environment, but further study is required to examine the environmental impacts of animal-based foods, and fruit and vegetable intake in depth.

Dietary greenhouse gas emissions of meat-eaters, fish-eaters, vegetarians and vegans in the UK

The production of animal-based foods is associated with higher greenhouse gas (GHG) emissions than plant-based foods. The objective of this study was to estimate the difference in dietary GHG emissions between self-selected meat-eaters, fish-eaters, vegetarians and vegans in the UK. Subjects were participants in the EPIC-Oxford cohort study. The diets of 2,041 vegans, 15,751 vegetarians, 8,123 fish-eaters and 29,589 meat-eaters aged 20-79 were assessed using a validated food frequency questionnaire. Comparable GHG emissions parameters were developed for the underlying food codes using a dataset of GHG emissions for 94 food commodities in the UK, with a weighting for the global warming potential of each component gas. The average GHG emissions associated with a standard 2,000 kcal diet were estimated for all subjects. ANOVA was used to estimate average dietary GHG emissions by diet group adjusted for sex and age. The age-and-sex-adjusted mean (95 % confidence interval) GHG emissions in kilograms of carbon dioxide equivalents per day (kgCO2e/day) were 7.19 (7.16, 7.22) for high meat-eaters ( > = 100 g/d), 5.63 (5.61, 5.65) for medium meat-eaters (50-99 g/d), 4.67 (4.65, 4.70) for low meat-eaters ( < 50 g/d), 3.91 (3.88, 3.94) for fish-eaters, 3.81 (3.79, 3.83) for vegetarians and 2.89 (2.83, 2.94) for vegans. In conclusion, dietary GHG emissions in self-selected meat-eaters are approximately twice as high as those in vegans. It is likely that reductions in meat consumption would lead to reductions in dietary GHG emissions.

Greenhouse gas emissions of realistic dietary choices in Denmark: the carbon footprint and nutritional value of dairy products

BACKGROUND

Dairy products are important in a healthy diet due to their high nutritional value; they are, however, associated with relatively large greenhouse gas emissions (GHGE) per kg product. When discussing the need to reduce the GHGE caused by the food system, it is crucial to consider the nutritional value of alternative food choices.

OBJECTIVE

The objective of this study was to elucidate the role of dairy products in overall nutrition and to clarify the effects of dietary choices on GHGE, and to combine nutritional value and GHGE data.

METHODS

We created eight dietary scenarios with different quantity of dairy products using data from the Danish National Dietary Survey (1995-2006). Nutrient composition and GHGE data for 71 highly consumed foods were used to estimate GHGE and nutritional status for each dietary scenario. An index was used to estimate nutrient density in relation to nutritional recommendation and climate impact for solid food items; high index values were those with the highest nutrient density scores in relation to the GHGE.

RESULTS

The high-dairy scenario resulted in 27% higher protein, 13% higher vitamin D; 55% higher calcium; 48% higher riboflavin; and 18% higher selenium than the non-dairy scenario. There was a significant correlation between changes in calcium and changes in vitamin D, selenium, and riboflavin content (P=0.0001) throughout all of the diets. The estimated GHGE for the dietary scenario with average-dairy consumption was 4,631 g CO2e/day.

CONCLUSIONS

When optimizing a diet with regard to sustainability, it is crucial to account for the nutritional value and not solely focus on impact per kg product. Excluding dairy products from the diet does not necessarily mitigate climate change but in contrast may have nutritional consequences.

Reducing energy intake and energy density for a sustainable diet: a study based on self-selected diets in French adults

BACKGROUND

Studies on theoretical diets are not sufficient to implement sustainable diets in practice because of unknown cultural acceptability. In contrast, self-selected diets can be considered culturally acceptable.

OBJECTIVE

The objective was to identify the most sustainable diets consumed by people in everyday life.

DESIGN

The diet-related greenhouse gas emissions (GHGE) for self-selected diets of 1918 adults participating in the cross-sectional French national dietary survey Individual and National Survey on Food Consumption (INCA2) were estimated. "Lower-Carbon," "Higher-Quality," and "More Sustainable" diets were defined as having GHGE lower than the overall median value, a probability of adequate nutrition intake (PANDiet) score (a measure of the overall nutritional adequacy of a diet) higher than the overall median value, and a combination of both criteria, respectively. Diet cost, as a proxy for affordability, and energy density were also assessed.

RESULTS

More Sustainable diets were consumed by 23% of men and 20% of women, and their GHGE values were 19% and 17% lower than the population average (mean) value, respectively. In comparison with the average value, Lower-Carbon diets achieved a 20% GHGE reduction and lower cost, but they were not sustainable because they had a lower PANDiet score. Higher-Quality diets were not sustainable because of their above-average GHGE and cost. More Sustainable diets had an above-average PANDiet score and a below-average energy density, cost, GHGE, and energy content; the energy share of plant-based products was increased by 20% and 15% compared with the average for men and women, respectively.

CONCLUSIONS

A strength of this study was that most of the dimensions for "sustainable diets" were considered, ie, not only nutritional quality and GHGE but also affordability and cultural acceptability. A reduction in diet-related GHGE by 20% while maintaining high nutritional quality seems realistic. This goal could be achieved at no extra cost by reducing energy intake and energy density and increasing the share of plant-based products.