Climate change mitigation through dietary change: a systematic review of empirical and modelling studies on the environmental footprints and health effects of 'sustainable diets'

Can micronutrient requirements be met by diets from sustainable sources: outcomes of dietary modelling studies using diet optimization

BACKGROUND

Consumption of diets from sustainable sources is required for planetary health, however, large sections of the population, including females of reproductive age and children, will be at risk of not meeting their micronutrient (MN) requirements in a complete transition to plant-based foods. Constrained diet optimization methods use mathematical programming to construct diets that meet predefined parameters and may contribute towards modelling dietary solutions that meet nutritional and planetary targets.

OBJECTIVE

Review the evidence from diet optimization studies proposing solutions to ensure MN availability in the context of a transition to diets from sustainable sources.

APPROACH

Narrative review focusing on literature published over the last five years.

RESULTS

Dietary modelling using diet optimization can design a range of omnivorous and plant-based diets that meet individual MN requirements, have reduced environmental impacts, and minimize deviation from culturally acceptable dietary practices. Using data from large-scale dietary surveys, diet optimization can support development of food-based dietary guidelines; identify limiting MNs in a particular context or a conflict between constraints e.g. nutrition and environment; explore food-based strategies to increase nutrient supply, such as fortification; and support trial design. Methods used and outcomes reported are sources of variability. Individual-level dietary data and MN requirements for population sub-groups such as females of reproductive age and children are important requirements. Although maintaining iron and zinc intakes are regularly reported to present challenges in diets from sustainable sources, few studies have considered bioavailability, which reduces with increased dietary phytate. These and other data gaps including acceptability and affordability must be addressed to improve the applicability of modelling outcomes in population recommendations.

CONCLUSIONS

Dietary modelling using diet optimization can be useful in the design of more sustainable diets that meet MN requirements, however, translation of outcomes into dietary intervention studies is required to test real-world application and adoption into dietary guidelines.

Alignment between greenhouse gas emissions reduction and adherence the EAT-Lancet diet: A modeling study based on the NutriNet-Santé cohort

The potential of the EAT-Lancet reference diet, which promotes a healthy diet within planetary limits, to reduce greenhouse gas emissions (GHGe) remains understudied. This study examines the role of nutritional and acceptability constraints in reducing GHGe through diet optimization, and tests the alignment between GHGe reduction and the EAT-Lancet score. The study used data from 29,413 NutriNet-Santé participants to model French diets and evaluate their environmental, nutritional, economic, and health impact. The Organic Food Frequency Questionnaire was used to assess organic and conventional food consumed, and the Dialecte database was used to estimate the diet environmental impacts. Quality of diets were also evaluated based using the PNNS-GS2 (Programme National Nutrition-Santé 2 guidelines score). When testing minimizing GHGe under strict nutritional and acceptability constraints, it was possible to reduce GHGe up to 67 % (from 4.34 in the observed diet to GHGe = 1.45 kgeqCO2/d) while improving the EAT score by 103 % with 91 % of the food as organic. Greater reductions required relaxation of some constraints. When testing maximizing EAT score under gradual reduction in GHGe, the adherence to the EAT-Lancet diet was not significantly affected by the gradual reduction in GHGe. To maximize EAT score with 75 % reduction in GHGe (1.09 kgeqCO2/d), less strict constraints on the bioavailability of iron and zinc are necessary. The EAT score improved by 141 %, while land occupation decreased by 57 %, compared to the observed value. The diet contained 94 % of organic foods. There was some alignment between the degree of adherence to the EAT-Lancet diet and the reduction in GHGe, but other diets may also lead to a strong reduction in GHGe. Thus, GHGe can be greatly reduced by dietary choices, but require profound reshaping of diets which must be coupled with changes in other areas of the food chain.

Adherence to the Mediterranean diet is associated with sustainable nutrition and environmental footprints on higher educated individuals

Introduction: This study aimed to investigate the relationship between Med-Diet adherence with sustainable nutrition and environmental footprints in academicians. Methods: The study involved 153 academicians aged 23-64 working in a university in Turkey. Data were collected through a questionnaire including socio-demographic characteristics, anthropometric measurements, Mediterranean Diet Adherence Scale (MEDAS) and Sustainable and Healthy Eating Behaviours Scale (SHEBS). Carbon and water footprints were calculated. Results: All sub-scales of SHEBS were higher in individuals who adhered to Med-Diet than those who did not (p<0.05). The carbon and water footprints of individuals with high adherence to the Med-Diet were lower than those of no adherence (p<0.05). Each 1-point increase in MEDAS score was associated with a 1-point increase in SHEBS score, a 0.15 CO2 eq/kg and a 0.001 m3/year decrease in the amount of carbon and water footprint of food. Conclusion: Higher adherence to the Med-Diet was associated with higher sustainable nutrition behaviours, and lower environmental footprints.

The role of ultra-processed foods in plant-based diets: associations with human health and environmental sustainability

PURPOSE

Investigate the associations of ultra-processed foods (UPF) in healthful (hPDI) and unhealthful (uPDI) plant-based diets with all-cause mortality, greenhouse gas emissions (GHGE), and blue water consumption (BWC).

METHODS

Analyses were based on 35,030 participants (20-70 years; 74% females) from the EPIC-NL cohort who were followed up from 1993 to 1997 through 2014. Plant-based diet indices (hPDI and uPDI) and UPF consumption were calculated from a validated FFQ, assessed at baseline. Cox proportional hazard and multiple linear regression models were used to estimate associations between combined quartiles of the PDI indices and UPF consumption.

RESULTS

With lower hPDI and higher UPF diets as the reference, we observed the following. Risk estimates of all-cause mortality were 0.98 (95% CI: 0.83, 1.16) for lower UPF consumption, 0.86 (95% CI: 0.68, 1.08) for higher hPDI, and 0.78 (95% CI: 0.66, 0.89) for combined higher hPDI and lower UPF consumption. Results with the uPDI were inconclusive. Mean differences in GHGE and BWC were 1.4% (95% CI: 0.3, 2.4) and 1.6% (95% CI: -0.5, 3.7) for lower UPF consumption, -7.4% (95% CI: -8.6, -6.4) and 9.6% (95% CI: 7.2, 12.0) for higher hPDI, and - 6.8% (95% CI: -7.4, -6.1) and 13.1% (95% CI: 11.6, 14.8) for combined higher hPDI and lower UPF consumption. No apparent conflict between environmental impacts was observed for the uPDI; GHGE and BWC were lower for higher uPDI scores.

CONCLUSION

Mortality risk and environmental impacts were mostly associated with the amount of plant-based foods and to a lesser extent UPF in the diet. Shifting to a more healthful plant-based diet could improve human health and reduce most aspects of environmental impact (GHGE, but not BWC) irrespective of UPF consumption.

Evaluation of the Climate Impact and Nutritional Quality of Menus in an Italian Long-Term Care Facility

Global warming poses a significant threat to our planet, with the food sector contributing up to 37% of total greenhouse gas emissions. This study aimed to assess the climate change impact and healthiness of menus in a long-term care facility in Italy. We analyzed two 28-day cyclical menus using the carbon footprint (CF) and the Modified EAT-Lancet Diet Score (MELDS) to evaluate adherence to the Planetary Health Diet (PHD). Monte Carlo simulations were employed to explore 20,000 daily menu permutations. Results showed that the mean GHGEs of spring/summer and autumn/winter daily menus were 2.64 and 2.82 kg of CO2eq, respectively, with 99% of menus exceeding the 2.03 kg of CO2eq benchmark. Only 22% of menus were adherent to the PHD, with MELDSs ranging from 12 to 29. A strong inverse association between the CF and adherence to the PHD was observed. These findings suggest significant potential for reducing the CFs of meals served in nursing homes while promoting adherence to a planetary diet, presenting an opportunity to set new standards in caregiving and environmental sustainability.

Industrially Produced Plant-Based Food Products: Nutritional Value and Degree of Processing

The plant-based food market is rapidly growing, offering innovative options to meet consumer expectations. However, a comprehensive analysis of the nutritional quality of these foods is lacking. We aimed to characterize industrial plant-based food products' nutritional value and degree of processing. A cross-sectional study was conducted on two market-leading Portuguese food retail chains by assessing the nutritional composition of all the available pre-packaged plant-based food products (n = 407). These products were categorized into meal alternatives, dairy alternatives, and other products containing dairy/meat alternative ingredients including ready meals and desserts. The products' nutritional quality was assessed according to the cut-offs established by the Portuguese Directorate General of Health [DGS] on total fat, saturated fat, sugar, and salt, and considering the degree of processing using NOVA classification. One-tenth of the products were classified as having a high total fat, saturated fat, sugars, or salt content. In some sub-categories, half of foods were classified as high in saturated fat, and over two-thirds were considered high salt products. Less than one-third exhibit a good nutritional profile based on the national cut-offs. A total of 84.3% of plant-based food products were ultra-processed. These findings emphasize the need to improve the nutritional profile of plant-based options.

The MED_EAT-IT approach: A modelling study to develop feasible, sustainable and nutritionally targeted dietary patterns based on the Planetary health diet

In 2019, the EAT-Lancet Commission introduced the Planetary Health Diet (PHD), a guide for creating 2500 kcal/day country-specific sustainable diets that promote health while reducing the environmental impact associated with food systems. The PHD was previously adapted to the Italian food context, resulting in the EAT-IT dietary pattern. However, this adaptation revealed several challenges in terms of nutritional adequacy, feasibility, and environmental impact. This study reports on strategies to improve the previous pattern and align it more closely with the Mediterranean Diet, resulting in the MED_EAT-IT pattern. The study also explores feasible strategies for adapting this pattern to different energy targets, enhancing its scalability and promoting personalized approaches. For the optimization of this pattern, a specific calculation tool was developed to introduce variation to the pattern, considering realistic and feasible serving sizes and frequency of consumption. This tool integrates a defined food ontology, food composition data, and two environmental impact metrics (Carbon and Water Footprint). To optimize nutritional adequacy, several adaptations of the amount within the different food groups were made, for instance by increasing cereals and animal source by 25.5% kcal/day and 36.2% kcal/day respectively compared to EAT-IT. The resulting 2500 kcal/die pattern meets all nutritional requirements except for vitamin D and does not hamper the possibility to limit environmental impact (Carbon Footprint increased only by 12.2% but Water Footprint decreased by 6.3%). Lower energy targets were achieved by modulating amounts of the different food groups to ensure nutritional adequacy. The strategies and tools proposed here could aid in optimizing dietary plans, evaluating their potential for environmental impact reduction, and identifying issues that could hinder their adoption. Furthermore, the analyses carried out pave the way for the potential future development of new or improved foods that may contribute to the optimization of nutritional and environmental impact of diets.

Circular food system approaches can support current European protein intake levels while reducing land use and greenhouse gas emissions

Protein transition and circular food system transition are two proposed strategies for supporting food system sustainability. Here we model animal-sourced protein to plant-sourced protein ratios within a European circular food system, finding that maintaining the current animal-plant protein share while redesigning the system with circular principles resulted in the largest relative reduction of 44% in land use and 70% in greenhouse gas (GHG) emissions compared with the current food system. Shifting from a 60:40 to a 40:60 ratio of animal-sourced proteins to plant-sourced proteins yielded a 60% reduction in land use and an 81% GHG emission reduction, while supporting nutritionally adequate diets. Differences between current and recommended total protein intake did not substantially impact minimal land use and GHG emissions. Micronutrient inadequacies occurred with less than 18 g animal protein per capita per day. Redesigning the food system varied depending on whether land use or GHG emissions were reduced-highlighting the need for a food system approach when designing policies to enhance human and planetary health.

Impact of consuming an environmentally protective diet on micronutrients: a systematic literature review

BACKGROUND

A global move toward consumption of diets from sustainable sources is required to protect planetary health. As this dietary transition will result in greater reliance on plant-based protein sources, the impact on micronutrient (MN) intakes and status is unknown.

OBJECTIVE

Evaluate the evidence of effects on intakes and status of selected MNs resulting from changes in dietary intakes to reduce environmental impact. Selected MNs of public health concern were vitamins A, D, and B12, folate, calcium, iron, iodine, and zinc.

METHODS

We systematically searched 7 databases from January 2011 to October 2022 and followed the PRISMA guidelines. Eligible studies had to report individual MN intake and/or status data collected in free-living individuals from the year 2000 onward and environmental outcomes.

RESULTS

From the 10,965 studies identified, 56 studies were included, mostly from high-income countries (n = 49). Iron (all 56) and iodine (n = 20) were the most and least reported MNs, respectively. There was one randomized controlled trial (RCT) that also provided the only biomarker data, 10 dietary intake studies, and 45 dietary modeling studies, including 29 diet optimization studies. Most studies sought to reduce greenhouse gas emissions or intake of animal-sourced foods. Most results suggested that intakes of zinc, calcium, iodine, and vitamins B12, A, and D would decrease, and total iron and folate would increase in a dietary transition to reduce environmental impacts. Risk of inadequate intakes of zinc, calcium, vitamins A, B12 and D were more likely to increase in the 10 studies that reported nutrient adequacy. Diet optimization (n = 29) demonstrated that meeting nutritional and environmental targets is technically feasible, although acceptability is not guaranteed.

CONCLUSIONS

Lower intakes and status of MNs of public health concern are a potential outcome of dietary changes to reduce environmental impacts. Adequate consideration of context and nutritional requirements is required to develop evidence-based recommendations. This study was registered prospectively with PROSPERO (CRD42021239713).

Traditional japanese diet score and the sustainable development goals by a global comparative ecological study

BACKGROUND

Reducing the environmental impact of the food supply is important for achieving Sustainable Development Goals (SDGs) worldwide. Previously, we developed the Traditional Japanese Diet Score (TJDS) and reported in a global ecological study that the Japanese diet is associated with reducing obesity and extending healthy life expectancy etc. We then examined the relationship between the TJDS and environmental indicators.

METHODS

The average food (g/day/capita) and energy supplies (kcal/day/capita) by country were obtained from the Food and Agriculture Organization of the United Nations Statistics Division database. The TJDS was calculated from eight food groups (beneficial food components in the Japanese diet: rice, fish, soybeans, vegetables, and eggs; food components that are relatively unused in the traditional Japanese diet: wheat, milk, and red meat) by country using tertiles, and calculated the total score from - 8 to 8, with higher scores meaning greater adherence to the TJDS. We used Land Use (m2), Greenhouse gas (GHG) emissions 2007/2013 (kg CO2eq), Acidifying emissions (g SO2eq), Eutrophying emissions (g PO43- eq), Freshwater (L), and water use (L) per food weight by Poore et al. as the environmental indicators and multiplied these indicators by each country's average food supply. We evaluated the cross-sectional and longitudinal associations between the TJDS and environmental indicators from 2010 to 2020. This study included 151 countries with populations ≥ 1 million.

RESULTS

Land use (β ± standard error; -0.623 ± 0.161, p < 0.001), GHG 2007 (-0.149 ± 0.057, p < 0.05), GHG 2013 (-0.183 ± 0.066, p < 0.01), Acidifying (-1.111 ± 0.369, p < 0.01), and Water use (-405.903 ± 101.416, p < 0.001) were negatively associated with TJDS, and Freshwater (45.116 ± 7.866, p < 0.001) was positively associated with TJDS after controlling for energy supply and latitude in 2010. In the longitudinal analysis, Land Use (β ± standard error; -0.116 ± 0.027, p < 0.001), GHG 2007 (-0.040 ± 0.010, p < 0.001), GHG 2013 (-0.048 ± 0.011, p < 0.001), Acidifying (-0.280 ± 0.064, p < 0.001), Eutrophying (-0.132 ± 0.062, p < 0.05), and Water use (-118.246 ± 22.826, p < 0.001) were negatively associated with TJDS after controlling for confounders.

CONCLUSIONS

This ecological study suggests that the traditional Japanese dietary pattern might improve SDGs except Fresh water.

Potential for positive biodiversity outcomes under diet-driven land use change in Great Britain

Background

A shift toward human diets that include more fruit and vegetables, and less meat is a potential pathway to improve public health and reduce food system-related greenhouse gas emissions. Associated changes in land use could include conversion of grazing land into horticulture, which makes more efficient use of land per unit of dietary energy and frees-up land for other uses.

Methods

Here we use Great Britain as a case study to estimate potential impacts on biodiversity from converting grazing land to a mixture of horticulture and natural land covers by fitting species distribution models for over 800 species, including pollinating insects and species of conservation priority.

Results

Across several land use scenarios that consider the current ratio of domestic fruit and vegetable production to imports, our statistical models suggest a potential for gains to biodiversity, including a tendency for more species to gain habitable area than to lose habitable area. Moreover, the models suggest that climate change impacts on biodiversity could be mitigated to a degree by land use changes associated with dietary shifts.

Conclusions

Our analysis demonstrates that options exist for changing agricultural land uses in a way that can generate win-win-win outcomes for biodiversity, adaptation to climate change and public health.

Environmental problem shifting from climate change mitigation: A mapping review

Climate change mitigation will trigger major changes in human activity, energy systems, and material use, potentially shifting pressure from climate change to other environmental problems. We provide a comprehensive overview of such "environmental problem shifting" (EPS). While there is considerable research on this issue, studies are scattered across research fields and use a wide range of terms with blurred conceptual boundaries, such as trade-off, side effect, and spillover. We identify 506 relevant studies on EPS of which 311 are empirical, 47 are conceptual-theoretical, and 148 are synthetic studies or reviews of a particular mitigation option. A systematic mapping of the empirical studies reveals 128 distinct shifts from 22 categories of mitigation options to 10 environmental impacts. A comparison with the recent IPCC report indicates that EPS literature does not cover all mitigation options. Moreover, some studies systematically overestimate EPS by not accounting for the environmental benefits of reduced climate change. We propose to conceptually clarify the different ways of estimating EPS by distinguishing between gross, net, and relative shifting. Finally, the ubiquity of EPS calls for policy design which ensures climate change mitigation that minimizes unsustainability across multiple environmental dimensions. To achieve this, policymakers can regulate mitigation options-for example, in their choice of technology or location-and implement complementary environmental policies.

Nutrition quality and food and packaging waste associated with the school food system: A pilot, citizen science study in an Irish secondary school

BACKGROUND

School is an important setting for creating healthy and sustainable food environments. Using participatory methods, this pilot study examined food and packaging waste and nutrition quality within the school food system.

METHODS

One secondary school in Ireland participated in a waste audit. Eleven male students (15-17 years) participated as citizen scientists. Students collected waste over 1 day and documented data on waste categories. Nutrition labels were photographed for analysis. Students created a video and participated in a focus group. Quantitative data were summarised using descriptive frequencies. A Nutrient Profile Model was applied to summarise nutrition quality. The focus group discussion was analysed using content analysis.

RESULTS

Highest weights of waste were organic waste (14.2 kg), paper and cardboard (5.0 kg), and hard plastics (4.1 kg). Materials banned by the European Union Single Use Plastics Directive were found. Recycling bins were contaminated with food waste. Nutrition labels from 132 food packages were analysed, of which 115 items (87%) were low-nutrient, energy dense foods. Confectionary, energy bars and desserts and savoury snacks were the most common packaged food groups. Students were not surprised by the unhealthy food choices; however, they were shocked and saddened at the waste practices. Their proposed solutions mapped across individual, community and organisational levels.

CONCLUSIONS

The methodologies allowed successful engagement with students on this topic. The use of unnecessary plastics to serve food, poor waste separation practices, and the production of avoidable waste from low-nutrient, energy-dense products were key issues identified. Students proposed solutions that are achievable in the short-term.

Simple dietary substitutions can reduce carbon footprints and improve dietary quality across diverse segments of the US population

Changing what foods we eat could reduce environmental harms and improve human health, but sweeping dietary change is challenging. We used dietary intake data from a nationally representative sample of 7,753 US children and adults to identify simple, actionable dietary substitutions from higher- to lower-carbon foods (for example, substituting chicken for beef in mixed dishes such as burritos, but making no other changes to the diet). We simulated the potential impact of these substitutions on dietary carbon emissions and dietary quality. If all consumers who ate the high-carbon foods instead consumed a lower-carbon substitute, the total dietary carbon footprint in the United States would be reduced by more than 35%. Moreover, if adopted, these substitutions would improve consumers' overall dietary quality by 4-10%, with benefits projected for all age, gender, and racial and ethnic groups. These results suggest that a 'small changes' approach could be a valuable starting point for addressing diet's impact on climate and health.

Meat reduction among post-secondary students: Exploration of motives, barriers, diets and preferences for meals with partial and full meat substitution

Before developing new meat reduction interventions to support increased sustainability, it is important to understand the motives, diets and preferences of consumers who have already made efforts to reduce meat consumption. While self-declaration has been typically used to identify meat reducers, food frequency data suggests some reducers still identify as omnivores, here termed transitional meat reducers. We compared these "transitional" meat reducers to self-declared meat reducers, unrestricted omnivores and vegetarians/vegans for differences in diet, motives for reducing meat, and perceived barriers to consuming more legumes (dried beans, peas or lentils) and plant-based meat alternative products (PBMAs). We also compared their intention to choose four specific entrees where legumes or PBMAs had partially or fully replaced meat. A convenience sample of Canadian university students completed an online survey (N = 438). 34% of participants were self-declared meat reducers, 16% transitional meat reducers, 33% unrestricted omnivores and 16% vegetarians/vegans. Frequency of eating red meat differed, with self-declared meat reducers eating red meat less often than either transitional meat reducers or unrestricted omnivores. Motives for meat reduction were similar in the two reducer groups. Transitional meat reducers reported significantly more frequent consumption of other protein foods and more barriers to legumes but not PBMA, than either unrestricted omnivores or self-declared meat reducers. Lastly, intention to consume all versions of entrees was very similar in both reducer groups, but with increased preference for full vs partial substitution among self-declared reducers. Transitional meat reducers may be a distinct group for meat reduction interventions compared to omnivores or self-declared reducers.

The motivations and practices of vegetarian and vegan Saudis

In the Middle East, particularly in Saudi Arabia, the offering of a meat dish to guests is a deeply embedded cultural tradition, and a meat-based diet is the standard in Saudi Arabia. Thus, the rise of veganism and vegetarianism within Saudi Arabia is surprising and worthy of attention, as is understanding the perceptions and motivations behind this phenomenon, particularly as they relate to food and sustainability. This research was designed to investigate this emerging phenomenon and to identify key differences in dietarian identity between Saudi vegetarians and vegans using Rosenfeld and Burrow's Dietarian Identity Questionnaire. Among other results, the vegan group scored significantly higher on the prosocial motivation construct, suggesting the desire to help society as a whole is a stronger motivating factor for vegans. As well, the vegan cohort scored higher in the personal motivation category. From an environmental and public health perspective, understanding the key factors motivating individuals to adopt a vegetarian or vegan diet in a meat-based culture like Saudi Arabia can be used to encourage others to pursue more healthy and sustainable food behaviors.

Exploring healthy and climate-friendly diets for Danish adults: an optimization study using quadratic programming

Background

A transition to healthy and sustainable diets has the potential to improve human and planetary health but diets need to meet requirements for nutritional adequacy, health, environmental targets, and be acceptable to consumers.

Objective

The objective of this study was to derive a nutritionally adequate and healthy diet that has the least deviation possible from the average observed diet of Danish adults while aiming for a greenhouse gas emission (GHGE) reduction of 31%, corresponding to the GHGE level of the Danish plant-rich diet, which lays the foundation for the current healthy and sustainable food-based dietary guidelines (FBDGs) in Denmark.

Methods

With an objective function minimizing the departure from the average observed diet of Danish adults, four diet optimizations were run using quadratic programming, with different combinations of diet constraints: (1) nutrients only (Nutri), (2) nutrients and health-based targets for food amounts (NutriHealth), (3) GHGE only (GHGE), and finally, (4) combined nutrient, health and GHGE constraints (NutriHealthGHGE).

Results

The GHGE of the four optimized diets were 3.93 kg CO₂-eq (Nutri), 3.77 kg CO₂-eq (NutriHealth) and 3.01 kg CO₂-eq (GHGE and NutriHealthGHGE), compared to 4.37 kg CO₂-eq in the observed diet. The proportion of energy from animal-based foods was 21%-25% in the optimized diets compared to 34% in the observed diet and 18% in the Danish plant-rich diet. Moreover, compared to the average Danish diet, the NutriHealthGHGE diet contained more grains and starches (44 E% vs. 28 E%), nuts (+230%), fatty fish (+89%), eggs (+47%); less cheese (-73%), animal-based fats (-76%), total meat (-42%); and very limited amounts of ruminant meat, soft drinks, and alcoholic beverages (all-90%), while the amounts of legumes and seeds were unchanged. On average, the mathematically optimized NutriHealthGHGE diet showed a smaller deviation from the average Danish diet compared to the Danish plant-rich diet (38% vs. 169%, respectively).

Conclusion

The final optimized diet presented in this study represents an alternative way of composing a nutritionally adequate and healthy diet that has the same estimated GHGE as a diet consistent with the climate-friendly FBDGs in Denmark. As this optimized diet may be more acceptable for some consumers, it might help to facilitate the transition toward more healthy and sustainable diets in the Danish population.

Plant to animal protein ratio in the diet: nutrient adequacy, long-term health and environmental pressure

Background

Animal and plant protein sources have contrasting relationships with nutrient adequacy and long-term health, and their adequate ratio is highly debated.

Objective

We aimed to explore how the percentage of plant protein in the diet (%PP) relates to nutrient adequacy and long-term health but also to environmental pressures, to determine the adequate and potentially optimal %PP values.

Methods

Observed diets were extracted from the dietary intakes of French adults (INCA3, n = 1,125). Using reference values for nutrients and disease burden risks for foods, we modeled diets with graded %PP values that simultaneously ensure nutrient adequacy, minimize long-term health risks and preserve at best dietary habits. This multi-criteria diet optimization was conducted in a hierarchical manner, giving priority to long-term health over diet proximity, under the constraints of ensuring nutrient adequacy and food cultural acceptability. We explored the tensions between objectives and identified the most critical nutrients and influential constraints by sensitivity analysis. Finally, environmental pressures related to the modeled diets were estimated using the AGRIBALYSE database.

Results

We find that nutrient-adequate diets must fall within the ~15-80% %PP range, a slightly wider range being nevertheless identifiable by waiving the food acceptability constraints. Fully healthy diets, also achieving the minimum-risk exposure levels for both unhealthy and healthy foods, must fall within the 25-70% %PP range. All of these healthy diets were very distant from current typical diet. Those with higher %PP had lower environmental impacts, notably on climate change and land use, while being as far from current diet.

Conclusion

There is no single optimal %PP value when considering only nutrition and health, but high %PP diets are more sustainable. For %PP > 80%, nutrient fortification/supplementation and/or new foods are required.

Insight into the Sustainability of the Mediterranean Diet: The Water Footprint of the Recommended Italian Diet

At present, as we face climate change and natural resource scarcity, one of the major challenges linking humans and the environment is to ensure sufficient, nutritious, safe, and affordable food for a rapidly growing world population. In a nutshell, "feed the world without destroying it". The water footprint (WF), i.e., the withdrawals of fresh water necessary to produce one kilogram of food product, is one of the key indicators of the environmental impact of diets. In this work, the WF of the food patterns suggested by the Italian Food Based Dietary Guidelines, considered a model of the Mediterranean Diet, was evaluated for the first time. The data reported here clearly demonstrate that the suggested Italian dietary patterns have a low WF, the reduction of which by replacing animal foods with plant foods is limited because the suggested consumption of meat is already low. Consumer choice in the consumption of specific products within a food group could further reduce the WF of the diet, underlining the need to provide correct information not only to consumers but also to farmers and producers to encourage them to make water-saving choices.

European dietitians as key agents of the green transition: An exploratory study of their knowledge, attitudes, practices, and training

Introduction

How food systems are currently provisioning food to the population is a matter of debate worldwide. Food systems, driven by widespread and increasing adherence to a westernized dietary pattern, are failing to meet people's basic needs and are draining natural resources. There is a push to make food systems more healthy, fair, and sustainable. To this end, action from all players is needed to meet the international agenda. In this regard, dietitians play a crucial role, as they can provide advice and promote actions that foster the adoption of more sustainable dietary patterns (SDP) as well as the promotion of sustainable food systems. As an emerging requirement in their training, it is crucial to know what dietitians know about SDP as well as their attitudes and current practices in this field in order to strengthen their competences and be key agents for the green transition. For this reason, the aim of the present study is to explore the knowledge, attitudes, practices, and training (KAPT) of European dietitians on SDP by administering an online survey.

Methods

Cross-sectional survey administered between April-August 2021 to dietitians based in the European countries with National Dietetic Associations or Education Associate Members affiliated to the European Federation of Associations of Dietitians (EFAD). Results were analyzed based on European region of professional practice (Northern/Southern/Western/South-East Europe), area of expertise and years of experience.

Results

Responses from 2211 dietitians from 25 countries were received, although the analysis was based on those that responded at least 90% of the survey (n=208). European dietitians are lacking training on SDP but are willing to learn more about it. Most dietitians perceive themselves as able to define an SDP, although aspects concerning social and economic sustainability were underestimated. Dietitians concur that barriers exist to the promotion of SDP, such as the lack of updated national food-based dietary guidelines and the absence of support from peers and managers. The country of professional activity seemed to be key to influencing dietitians' KAPT.

Discussion

These results emphasize the need to strengthen European dietitians' training in SDP and increase public/private commitment to consider dietitians as key professionals for the transition towards SDP.

Assessing the interlinkage between biodiversity and diet through the Mediterranean diet case

The adoption of healthy and sustainable diets, and the transition to sustainable food systems is of principal importance in order to counteract the double burden of climate change and non-communicable diseases. The Mediterranean diet (MD) has been widely recognized as a biodiversity and healthy nutrition resource to support sustainable development and food security. This study explored biodiversity in terms of food plants species, subspecies, varieties and races, and also addressed food-plant diversity differences between the MD and western-type consumption patterns. It was funded by the EU BioValue Project, aiming to promote the integration of underutilized crops into the food value chains. Using a two-stage scheme, data were selected from MEDUSA and Euro+Med databases (including 449 species, 2,366 subspecies, varieties, and races). Furthermore, 12 countries from North Africa and Europe were classified in two groups according to their sub-regional attributes and their traditionally most prevalent dietary pattern (MD or western-type diets). Statistical analysis showed that the mean of the majorly cultivated food plants in the MD was significantly higher than its counterpart in the Western-diet. Furthermore, no statistical difference was detected in the averages of native food plants between the MD group and the Western diet group, implying that the higher diversity in food plants observed in the MD seems to be attributed to crop utilization rather than crop availability. Our findings indicated the interlinkage between biodiversity and prevailing dietary patterns, and further underlined that biodiversity could constitute a prerequisite for dietary diversity, and hence nutrition security. In addition, this study demonstrated that diets and nutrition should be approached in a broader way within the context of both agro-food and ecological systems.

Impact on mortality of pathways to net zero greenhouse gas emissions in England and Wales: a multisectoral modelling study

BACKGROUND

The UK is legally committed to reduce its greenhouse gas emissions to net zero by 2050. We aimed to understand the potential impact on population health of two pathways for achieving this target through the integrated effects of six actions in four sectors.

METHODS

In this multisectoral modelling study we assessed the impact on population health in England and Wales of six policy actions relating to electricity generation, transport, home energy, active travel, and diets relative to a baseline scenario in which climate actions, exposures, and behaviours were held constant at 2020 levels under two scenarios: the UK Climate Change Committee's Balanced Pathway of technological and behavioural measures; and its Widespread Engagement Pathway, which assumes more substantial changes to consumer behaviours. We quantified the impacts of each policy action on mortality using a life table comprising all exposures, behaviours, and health outcomes in a single model.

FINDINGS

Both scenarios are predicted to result in substantial reductions in mortality by 2050. The Widespread Engagement Pathway achieves a slightly greater reduction in outdoor fine particulate matter air pollution of 3·2 μg/m3 (33%) and, under assumptions of appropriate ventilation, a greater improvement in indoor air pollution (a decrease in indoor-generated fine particulate matter from 9·4 μg/m3 to 4·6 μg/m3) and winter temperatures (increasing from 17·8°C to 18·1°C), as well as appreciably greater changes in levels of active travel (27% increase in metabolic equivalent hours per week of walking and cycling) by 2050. Additionally, the greater reduction in red meat consumption (50% compared with 35% under the Balanced Pathway) by 2050 results in greater consumption of fruits (17-18 g/day), vegetables (22-23 g/day), and legumes (5-7 g/day). Combined actions under the Balanced Pathway result in more than 2 million cumulative life-years gained over 2021-50; the estimated gain under the Widespread Engagement Pathway is greater, corresponding to nearly 2·5 million life-years gained by 2050 and 13·7 million life-years gained by 2100.

INTERPRETATION

Reaching net zero greenhouse gas emissions is likely to lead to substantial benefits for public health in England and Wales, with the cumulative net benefits being correspondingly greater with a pathway that entails faster and more ambitious changes, especially in physical activity and diets.

FUNDING

National Institute for Health Research and the Wellcome Trust.

Nutritionally adequate and environmentally respectful diets are possible for different diet groups: an optimized study from the NutriNet-Santé cohort

BACKGROUND

Research has shown that vegetarian diets have a low environmental impact, but few studies have examined the environmental impacts and nutritional adequacy of these diets together, even though vegetarian diets can lead to nutritional issues.

OBJECTIVES

Our objective was to optimize and compare 6 types of diets with varying degrees of plant foods (lacto-, ovolacto-, and pescovegetarian diets and diets with low, medium, and high meat content) under nutritional constraints.

METHODS

Consumption data in 30,000 participants were derived from the French NutriNet-Santé cohort using an FFQ. Diets were optimized by a nonlinear algorithm minimizing the diet deviation while meeting multiple constraints at both the individual and population levels: nonincrease of the cost and environmental impacts (as partial ReCiPe accounting for greenhouse gas emissions, cumulative energy demand, and land occupation, distinguishing production methods: organic and conventional), under epidemiologic, nutritional (based on nutrient reference values), and acceptability (according to the diet type) constraints.

RESULTS

Optimized diets were successfully identified for each diet type, except that it was impossible to meet the EPA (20:5n-3) + DHA (22:6n-3) requirements in lacto- and ovolactovegetarians. In all cases, meat consumption was redistributed or reduced and the consumption of legumes (including soy-based products), whole grains, and vegetables were increased, whereas some food groups, such as potatoes, fruit juices, and alcoholic beverages, were entirely removed from the diets. The lower environmental impacts (as well as individual indicators) observed for vegetarians could be attained even when nutritional references were reached except for long-chain n-3 (omega-3) fatty acids.

CONCLUSIONS

A low-meat diet could be considered as a target for the general population in the context of sustainable transitions, although all diets tested can be overall nutritionally adequate (except for n-3 fatty acids) when planned appropriately.This trial was registered at clinicaltrials.gov as NCT03335644.

Growing health: global linkages between patterns of food supply, sustainability, and vulnerability to climate change

Global food systems are developing rapidly, and have resulted in a large burden of disease and a high proportion of environmental resource use. We combined global data sources on food supply and trade, environmental footprints, burdens of disease, and vulnerability to climate change to explore patterns from 1990 to 2017. Four distinct patterns of food supply (animal sources and sugar, vegetables and nuts, starchy roots and fruits, and seafood and oils) were matched to health and environmental risks. The animal sources and sugar pattern was found to have the greatest environmental footprint and to be associated with a greater burden of chronic disease than any other pattern, although it was also associated with lower undernutrition. This pattern is globally predominant, but has begun to decrease in higher income countries. Countries where this pattern is predominant are generally among the least susceptible to climate change, whereas more susceptible countries tend to have more sustainable patterns of food supply. More countries that are susceptible to climate change are increasingly exporting a larger proportion than before of their cereals, fruit, and vegetables globally, which will lead to increased risks in global food security. To increase resilience to future shocks, dietary change towards more sustainable patterns should accelerate in high-income countries, and the food systems of the most susceptible countries should be protected.

The Environmental Impact of an Italian-Mediterranean Dietary Pattern Based on the EAT-Lancet Reference Diet (EAT-IT)

The definition of a healthy and sustainable diet is nowadays considered pivotal, but data related to environmental outcomes are still debated. In this study, we compared the carbon (CF) and water footprints (WF) of an Italian-Mediterranean (EAT-IT) dietary pattern designed on the "Planetary diet", with a pattern based on the Italian Dietary Guidelines (IDG). The influence of different food categories and food choices on environmental impact was assessed. To this aim, weekly dietary patterns were developed, considering food categories and related portions and frequencies of consumption. Results show that the EAT-IT dietary pattern, compared to the IDG, had a significantly lower CF (2.82 ± 1.07 and 3.74 ± 0.92 kg CO2/day, respectively) but not WF. Protein-rich foods were the main contributors to CF and WF in both dietary patterns. The increased substitution of frozen instead of fresh foods, imported instead of local fruits, greenhouse-grown instead of seasonal vegetables, and processed legume-based foods instead of unprocessed legumes caused an increasing worsening of the CF in both patterns, but with different magnitudes. Our analysis indicated that the EAT-IT dietary pattern can be considered sustainable for CF, but individual choices are likely to largely affect the final environmental outcomes.

Renal health benefits of sustainable diets in Japan: a review

Global warming may reduce food production and force people to adopt dietary habits of inadequate quantity or quality. Such dietary habits could trigger chronic kidney disease through inappropriate nutrition or lifestyle diseases. Livestock farming and other types of food production are responsible for many greenhouse gases. These problems are being emphasized as a diet-environment-health trilemma to be addressed on a global scale, with various methods being proposed toward its resolution. Diets like plant-based and low-protein diets not only potentially prevent the progression of chronic kidney disease, but are also rational from an environmental preservation perspective. Evidence from Japan on resolutions for this trilemma is sparse, but one concrete proposal is the use of traditional Japanese diets like washoku, the Okinawa diet, and the traditional Buddhist diet. However, traditional Japanese diets also have several problems, such as excessive salt content and caloric deficiencies, and need to be modified and incorporated into the current lifestyle. The progression of chronic kidney disease needs to be prevented with appropriate dietary treatment and environmental friendly manner.

Potential for positive biodiversity outcomes under diet-driven land use change in Great Britain

Background: A shift toward human diets that include more fruit and vegetables, and less meat is a potential pathway to improve public health and reduce food system-related greenhouse gas emissions. Associated changes in land use could include conversion of grazing land into horticulture, which makes more efficient use of land per unit of dietary energy and frees-up land for other uses. Methods: Here we use Great Britain as a case study to estimate potential impacts on biodiversity from converting grazing land to a mixture of horticulture and natural land covers by fitting species distribution models for over 800 species, including pollinating insects and species of conservation priority. Results: Across several land use scenarios that consider the current ratio of domestic fruit and vegetable production to imports, our statistical models suggest a potential for gains to biodiversity, including a tendency for more species to gain habitable area than to lose habitable area. Moreover, the models suggest that climate change impacts on biodiversity could be mitigated to a degree by land use changes associated with dietary shifts. Conclusions: Our analysis demonstrates that options exist for changing agricultural land uses in a way that can generate win-win-win outcomes for biodiversity, adaptation to climate change and public health.

The role of plant-based alternative foods in sustainable and healthy food systems: Consumption trends in the UK

A global transformation towards sustainable food systems is crucial for delivering on climate change mitigation targets worldwide. In high- and middle-income settings, plant-based meat and dairy alternatives present potential substitutes for animal sourced foods, and a pathway to transition to more sustainable diets. We examined plant-based alternative foods (PBAF) consumption trends in the UK by analysing repeated cross-sectional food consumption data from the National Diet and Nutrition Survey 2008-2019. Dietary data for 15,655 individuals aged 1.5 years and over were analysed to assess aggregate change in intake of PBAF and six other food groups that play a role in transformative dietary change. Characteristics associated with consumption of PBAF were explored using logistic regression, and consumption patterns in high and low meat consumers were explored by examining intake of potential animal product substitute food groups. The proportion of individuals reporting consumption of any PBAFs increased from 6.7% in 2008-2011, to 13.1% in 2017-2019 (p < 0.01). Compared to 2008-2011 PBAF consumption rose by 115% in 2017-2019 (p < 0.01). Females were 46% more likely than males to report consumption of PBAF (p < 0.01). Millennials (age 24-39 years) were the most likely generation to report PBAF consumption (p < 0.01 compared to generation Z (age 11-23 years) and traditionalists (age 75+ years)), as were individuals of the highest income tertile (p < 0.01). Among "low meat consumers", PBAF consumption was on average higher than "high meat consumers" (18.6 g versus 4.8 g PBAF per day, p < 0.01). Our results support the hypothesis of a pivotal role of PBAF in the transition towards sustainable food systems in the UK, by demonstrating they are becoming increasingly popular among UK consumers. This highlights the urgent need to assess in detail the environmental and health impacts of large scale and population-wide consumption of PBAF in comparison to their animal-based equivalents.

Advantages and limitations of the methodological approaches used to study dietary shifts towards improved nutrition and sustainability

Acting on diet is one of the changes required - in combination with actions on food production, transformation, and waste - to address the challenges of reducing the environmental impact of our food systems and eliminating all forms of malnutrition. The number of studies exploring how to move towards a more sustainable diet has exploded over the past decades, but there is a need to facilitate their understanding and use by policy makers and all other stakeholders possibly influencing diet sustainability. The aim of the present article is to propose a categorization of studies into 4 approaches, based on the type of methodology used to explore diet sustainability, and to highlight the principles, advantages, and limitations of each approach in order to help study users in their interpretation. The 4 approaches are: assessment of sustainability characteristics of hypothetical diets (approach 1) or existing diets (approach 2), identification of existing "positive deviants" (approach 3), and design of more sustainable diets with constrained optimization (approach 4). Specificities and key findings drawn from each approach are described, and challenges for future studies are discussed.

Dietitians Australia position statement on healthy and sustainable diets

It is the position of Dietitians Australia that to promote human and planetary health, a food system transformation is needed that enables the population to adopt healthy and sustainable diet-related practices. A healthy and sustainable diet must (i) be nutritionally adequate, healthy and safe, (ii) have low environmental impact and be protective of natural resources and biodiversity, (iii) be culturally acceptable and (iv) be accessible, economically fair and affordable. Dietitians Australia acknowledges that it is critical to prioritise Indigenous knowledges in consultation, policy-making and implementation processes to achieve these recommendations. In facilitating the uptake of healthy and sustainable diets, dietitians are contributing to the transformation of our current food system that is urgently required to nourish present and future generations within planetary boundaries. In developing this position statement, opportunities for future research have been identified including those to advance the professions' capacity to improve environmental sustainability outcomes across all areas of practice. To achieve a population-level shift towards this diet, Dietitians Australia recommends: (i) the development of a National Food and Nutrition Strategy which honours Indigenous knowledges on food systems, (ii) the integration of sustainability principles in Australia's dietary guidelines, (iii) the reorientation of our food environment to prioritise access to healthy and sustainable foods, and (iv) investment in capacity building activities to equip the current and future nutrition and dietetics workforce.

Evidence-informed policy for tackling adverse climate change effects on health: Linking regional and global assessments of science to catalyse action

Robin Fears and co-authors discuss evidence-informed regional and global policy responses to health impacts of climate change.

Eat Well to Fight Obesity… and Save Water: The Water Footprint of Different Diets and Caloric Intake and Its Relationship With Adiposity

Water scarcity and excess adiposity are two of the main problems worldwide and in Mexico, which is the most obese country in the world and suffers from water scarcity. Food production represents 90% of a person's water footprint (WF), and healthy diets can lead to less WF than do unhealthy diets related to obesity. We calculated the WF of the diet and caloric intake of adults in Mexico and analyzed its relationship with adiposity. Also, the risk of water expenditure due to adiposity and adherence to dietary recommendations regarding WF of international healthy diets were examined. A Food Consumption Frequency Questionnaire (FCFQ) was applied to 395 adults. Body mass index (BMI), associated with adiposity indicators, was used as a reference for grouping a sample into adiposity levels. The WF was calculated according to the WF Assessment Method, considering correction factors and accounting for water involved in cooking and food washing. Our results showed that the Mexican diet spends 6,056 liters per person per day (L p-1d-1) and is 55% higher than international healthy diets WF. Consumption of beef, milk, fruits, chicken, and fatty cereals represented 56% of total WF. Strong relations appeared between hypercaloric diets and high WF. Diets of people with excess adiposity generated statistically higher WF with extra expenses of 729 L p-1d-1 compared with the normal adiposity population. Following nutritional recommendations offers a protective factor in water care, whereas not adhering to these represents a risk up to 93 times greater of water expenditure regarding international healthy diets. Therefore, both for the general population and to regulate obesity, adequate diets can help mitigate the problem of water scarcity.