This cross-sectional study examined the barriers and facilitators that influence vegetarian menu choices in a university cafeteria in Geneva, Switzerland. As a first step, an online survey developed by the authors based on the Capability, Opportunity, and Motivation Behaviour (COM-B) model was e-mailed to all university students and staff. In the second step, focus groups (FG) were held to complete the survey responses and identify what needed to be changed to promote the choice of the vegetarian menu in the cafeteria. Data from 304 participants collected through the survey was analysed. The main mentioned barriers were lack of vegetarian options, tastelessness and insufficient satiation. The facilitators that emerged from the survey were the price of the vegetarian menu for students and health and environmental benefits. Thirteen people participated in four FG sessions, which were analysed using thematic analysis. Five themes were identified: spontaneous menu selection, predefined menu selection, influence of opportunity on menu selection, influence of environmental sensitivity on menu selection, and threat to identity in menu selection. The choice of a vegetarian menu in a university cafeteria was mainly influenced by the attractiveness and taste of the plate. Future strategies to reduce food-related greenhouse gas emissions should (a) ensure the quality and attractiveness of the vegetarian menu, especially to appeal to the more resistant, such as men and omnivores, and (b) inform consumers about the guarantee of balanced nutrient intake of the vegetarian menu offered in the cafeteria, and about health and environmental benefits.

Adolescence is an important life-stage during which shifts towards more healthy and sustainable diets can be promoted. Adolescents have increasing influence over their food choices informed by their developing personal knowledge and values, impacting long-term dietary behaviours into adulthood(1). We aimed to review the recent literature regarding adolescents’ perceptions of environmentally sustainable diets, and interventions to support adolescents to eat sustainably. We reviewed published literature that focussed on adolescent participants and their perceptions of, or interventions to support, sustainable dietary habits. Five electronic databases were searched to include studies published since 2012 that met the inclusion criteria. The JBI approach and PRISMA-Sc checklist(2) was used for source screening, data extraction and presentation of data. Data was extracted including study characteristics, methodology and results in relation to each research question. The extracted data was reported, synthesised and discussed in the context of the food system framework(3) and broader research. Twenty-eight articles were included in the review. Findings suggest that adolescents’ understanding of what constitutes sustainable eating is low. Most adolescents, when asked, were unsure of what constitutes sustainable eating, or a plant-based diet. The environmental impact of the production methods, transport and packaging of foods was most commonly reported when adolescents considered the environmental impact of their foods. The most commonly perceived barrier to consuming sustainable foods mentioned was cost, particularly by adolescents from lower socioeconomic backgrounds. Other barriers include unappealing taste, appearance or smell of ‘sustainable’ food items (particularly those that were vegetarian). Geographical limitations impacting the ability to grow or purchase local and organic products were also mentioned as barriers to consuming sustainable foods. Adolescents reported a lack of understanding of sustainable diets, and distrust of sustainability-related claims from fast-food outlets regarding the quality or source of ingredients, making it difficult to make informed food choices. Additionally, behaviours conflicting with personal and/or group norms were noted as barriers to adopting sustainable dietary habits. Adolescents that had previously received relevant education, valued nature and health, or were from a rural or indigenous community, were more likely to value environmentally sustainable food choices. Interventions which target adolescents’ cognitive understanding and aspiration to make sustainable food choices appear to improve their attitudes towards sustainable food, whereas interventions to increase the availability of sustainable foods improved the environmental sustainability of adolescents’ dietary intake. Multicomponent, tailored and community-based interventions were most effective however the long-term effect of these interventions remains unclear. More research is needed in diverse countries and settings, with consideration of adolescents’ level of autonomy in food choice and long term-effectiveness of interventions.

Based on the World Health Organization’s definition(1), sustainable healthy diets are “dietary patterns that promote all dimensions of an individuals’ health and well-being; have low environmental pressure and impact; are accessible, affordable, safe and equitable; and are culturally acceptable”. Over the past decade, there has been an increasing interest in the environmental sustainability of diets, but little attention has been paid to the nutrient adequacy, consumer acceptability and affordability of such diets. Such knowledge is particularly scarce in New Zealand where approximately 40% of adults and 20% of children may live under severe to moderate food insecurity(2,3). The iOTA Model® is a dietary optimisation tool designed to fill this gap by bringing the various aspects of diet sustainability together and providing evidence-based knowledge on not just the environmental impact of food but also its economic and nutritional sustainability at a national level. The iOTA Model® was constructed using mixed integer linear programming by integrating New Zealand-specific dietary data. This underlying data was obtained from various open-access sources including but not limited to New Zealand’s Food Composition Database, New Zealand Total Diet Study and the nutrient reference values published by the Ministry of Health. Diet-related greenhouse gas emissions were also incorporated into the model based on the data obtained from the scientific literature. Results derived from the preliminary development of the iOTA Model® suggest that meeting nutrient adequacy is possible with minimal dietary pattern changes in New Zealand. It is also evident that adhering to dietary guidelines may provide 26% reduction in dietary greenhouse gas emissions. This is consistent with the findings of previous studies showing that following dietary guidelines alone assists reduction of dietary greenhouse gas emissions. Further features such as digestibility and bioavailability considerations have also been incorporated as part of the iOTA Model®, allowing for a more accurate estimation of nutrient supply. The model will be available as an open-access tool and will allow users to explore various sustainability implications of their diet.

The objective of this study was to describe changes in sustainable dietary behaviours (those that support environmental, economic, and physical health) among a sample of US adults during the COVID-19 pandemic and to examine differences in changes by individuals’ race/ethnicity and socioeconomic status. Therefore, a cross-sectional online survey study was conducted in April 2021 (N = 1,488, mean age = 42.7 (SD = 12.6)) receiving outpatient care from Michigan Medicine, the University of Michigan health system. Enrolment quotas were established to ensure a diverse sample—one-third of participants identified as African American/Black, one-third Hispanic/Latino, one-third White, and one-third low-income. Participants reported engaging in more behaviours that are supportive of a sustainable diet one year into the COVID-19 pandemic compared to before. This is particularly true regarding ecologically and economically sustaining behaviours such as taking fewer trips to the grocery store, increased use of home grocery delivery, increased cooking at home, and greater consumption of healthy foods. Not all behaviour changes promoted sustainable food systems; namely, the use of farmer’s markets and Community Supported Agriculture (CSAs) declined. White and high-income participants were more likely than African American/Black, Hispanic/Latino, and low-income individuals to engage in ecologically and economically sustainable dietary behaviours during the pandemic. Meanwhile, African American/Black participants reported large increases in physical health sustainable dietary behaviours. To support the continuation of greater engagement with sustainable diets, policies that increase access to public transportation, limit the frequency with which consumers have groceries delivered, increase work-from-home options, and improve access for low-income populations should be prioritised.

Reducing meat consumption is essential to curb further climate change and limit the catastrophic environmental degradation resulting from the current global food system. However, consumers in industrialised countries are hesitant to reduce their meat intake, often because they find plant-based foods less appealing. Despite the climate emergency, eating meat is still perceived as the norm, and recommended in most national dietary guidelines. To support the transition to more sustainable diets by providing insights for increasing the appeal of plant-based foods to mainstream consumers, this review presents recent research findings on how people think and communicate about meat-based and plant-based foods. The key findings we review include: (1) while vegans think about plant-based foods in terms of enjoyable eating experiences, omnivores think about plant-based foods in terms of health, vegan identity and other abstract information that does not motivate consumption in the moment. (2) Packages of ready-meals and social media posts on Instagram present plant-based foods with fewer references to enjoyable eating experiences than meat-based foods. (3) Presenting plant-based foods with language that references enjoyable eating experiences increases their appeal, especially for habitual meat eaters. This language includes words about sensory features of the food (e.g., crunchy, creamy), eating context (e.g. pub; with family) and immediate positive consequences of eating (e.g. comforting, delicious). In contrast, the term ‘vegan’ is strongly associated with negative stereotypes. Hence, rather than referring to being vegan, meat-free or healthy, the language used for plant-based foods should refer to sensory appeal, attractive eating situations and enjoyment.

Globally, diet quality is poor, with populations failing to achieve national dietary guidelines. Such failure has been consistently linked with malnutrition and poorer health outcomes. In addition to the impact of diet on health outcomes, it is now accepted that what we eat, and the resulting food system, has significant environmental or planetary health impacts. Changes are required to our food systems to reduce these impacts and mitigate the impact of climate change on our food supply. Given the complexity of the interactions between climate change, food and health, and the different actors and drivers that influence these, a systems-thinking approach to capture such complexity is essential. Such an approach will help address the challenges set by the UN 2030 Agenda for sustainable development in the form of the sustainable development goals (SDG). Progress against SDG has been challenging, with an ultimate target of 2030. While the scientific uncertainties regarding diet and public and planetary health need to be addressed, equal attention needs to be paid to the structures and systems, as there is a need for multi-level, coherent and sustained structural interventions and policies across the full food system/supply chain to effect behaviour change. Such systems-level change must always keep nutritional status, including impact on micronutrient status, in mind. However, benefits to both population and environmental health could be expected from achieving dietary behaviour change towards more sustainable diets.

The focus of nutritionists is on improvement of the health impact of current diets. Therefore, it is important to ask the question whether healthy diets are more sustainable. This review provides an overview on the research on synergies between health and sustainability. Synergies are found from shifts from animal-based to plant-based diets, from ultra-processed foods to fresh and whole foods and from reduction of food waste. The importance of looking at sustainability of the present diets has led to steps made in Europe to incorporate sustainability into food-based dietary guidelines. Examples from UK, Nordics, Belgium and the Netherlands are given. World Wildlife Fund has summarised the insides in a future-proof diet: the planet-based diet within planetary boundaries.

The gut microbiome is a key element for health preservation and disease prevention. Nevertheless, defining a healthy gut microbiome is complex since it is modulated by several factors, such as host genetics, sex, age, geographical zone, drug use, and, especially, diet. Although a healthy diet has proven to increase microbial alpha and beta diversity and to promote the proliferation of health-related bacteria, considering the current environmental and nutritional crisis, such as climate change, water shortage, loss of diversity, and the obesity pandemic, it should be highlighted that a healthy diet is not always sustainable. Sustainable diets are dietary patterns that promote all dimensions of people’s health and well-being while exerting low pressure on the environment, and being accessible, affordable, safe, equitable, and culturally acceptable. Examples of diets that tend to be sustainable are the Planetary Health Diet of the EAT-Lancet Commission or territorial diets such as the Mediterranean and the Traditional Mexican diet (milpa diet), adapted to specific contexts. These diets are principally plant-based but include small or moderate amounts of animal-based foods. Characterising the effects of sustainable diets on gut microbiota is urgent to ensure that the benefits for human health are aligned with environmental preservation and respect the sociocultural aspects of individuals.

The transition towards more plant-based diets may pose risks for bone health such as low vitamin D and Ca intakes. Findings for the contribution of animal and plant proteins and their amino acids (AA) to bone health are contradictory. This 6-week clinical trial aimed to investigate whether partial replacement of red and processed meat (RPM) with non-soya legumes affects AA intakes and bone turnover and mineral metabolism in 102 healthy 20–65-year-old men. Participants were randomly assigned to diet groups controlled for RPM and legume intake (designed total protein intake (TPI) 18 E%): the meat group consumed 760 g RPM per week (25 % TPI) and the legume group consumed non-soya legume-based products (20 % TPI) and 200 g RPM per week, the upper limit of the Planetary Health Diet (5 % TPI). No differences in bone (bone-specific alkaline phosphatase; tartrate-resistant acid phosphatase 5b) or mineral metabolism (25-hydroxyvitamin D; parathyroid hormone; fibroblast growth factor 23; phosphate and Ca) markers or Ca and vitamin D intakes were observed between the groups (P > 0·05). Methionine and histidine intakes were higher in the meat group (P ≤ 0·042), whereas the legume group had higher intakes of arginine, asparagine and phenylalanine (P ≤ 0·013). Mean essential AA intakes in both groups met the requirements. Increasing the proportion of non-soya legumes by reducing the amount of RPM in the diet for 6 weeks did not compromise bone turnover and provided on average adequate amounts of AA in healthy men, indicating that this ecologically sustainable dietary change is safe and relatively easy to implement.

Mexico is going through an environmental and nutritional crisis related to unsustainable dietary behaviours. Sustainable diets could solve both problems together. This study protocol aims to develop a three-stage, 15-week mHealth randomised controlled trial of a sustainable-psycho-nutritional intervention programme to promote Mexican population adherence to a sustainable diet and to evaluate its effects on health and environmental outcomes. In stage 1, the programme will be designed using the sustainable diets, behaviour change wheel and capability, opportunity, motivation, and behaviour (COM-B) models. A sustainable food guide, recipes, meal plans and a mobile application will be developed. In stage 2, the intervention will be implemented for 7 weeks, and a 7-week follow-up period in a young Mexican adults (18–35 years) sample, randomly divided (1:1 ratio) into a control group (n 50) and an experimental group (n 50), will be divided into two arms at week 8. Outcomes will include health, nutrition, environment, behaviour and nutritional-sustainable knowledge. Additionally, socio-economics and culture will be considered. Thirteen behavioural objectives will be included using successive approaches in online workshops twice a week. The population will be monitored using the mobile application consisting of behavioural change techniques. In stage 3, the effects of the intervention will be assessed using mixed-effects models on dietary intake and quality, nutritional status, physical activity, metabolic biomarkers (serum glucose and lipid profile), gut microbiota composition and dietary water and carbon footprints of the evaluated population. Improvements in health outcomes and a decrease in dietary water and carbon footprints are expected.

Dietary behaviours and the food systems in which they occur have a significant impact on climate change. The 2022 Intergovernmental Panel on Climate Change (IPCC) reports and other major climate reports have identified population-level dietary shifts towards balanced, sustainable healthy diets as an important mitigation (i.e. prevention) solution for climate change. Thus, public health nutrition researchers and practitioners have a crucial role to play in combatting the climate crisis. They have the content expertise, interdisciplinary training and technical skills needed to facilitate wide-scale dietary behaviour changes at multiple levels of influence and ultimately improve both human and planetary health. This commentary article: (i) summarises how dietary behaviours and food systems contribute to climate change, with a particular focus on high-income countries; (ii) reviews food-system-related climate change mitigation solutions most relevant to public health nutrition researchers and practitioners; and (iii) identifies key gaps in the literature and future research directions for the field.

This randomised online experiment aimed to investigate how eco-labelling and social nudging influenced sustainable food choice, as well as consider the effect of motivation to act sustainably. Participants were UK adults ≥18 years (n = 1399). Participants were asked to choose a hypothetical meal (beef, chicken or vegetarian burrito) and were randomly allocated to one of three conditions varying in labelling: eco-labelling; social nudge or control (no label). Co-primary outcomes were the frequency that the vegetarian and chicken burritos were chosen (i.e., the more sustainable food choices). There was evidence that more vegetarian (OR = 3.3 [95% CI 2.0, 5.3]) and chicken (OR = 2.5 [95% CI 1.8, 3.4]) burrito choices were made in the eco-label condition, over the beef burrito, compared to the control condition. In the social nudge condition, there was evidence that participants chose a vegetarian burrito over a beef burrito (OR = 1.7 [95% CI 1.1, 2.7]), but not a vegetarian burrito over a chicken burrito (OR = 1.4 [95% CI 0.9, 2.2]). Although both labels were effective at promoting participants to make more sustainable food choices, the eco-label was the most effective. Choice of burrito was modified by motivation to act sustainably across all conditions. This study suggests that future policy could include eco-labelling and/or a social nudge to reduce meat consumption and meet global climate change targets.

A future sustainable dietary pattern for Japanese is yet undefined. This study aimed to explore more sustainable Japanese diets that are nutritious, affordable and with low greenhouse gas emissions (GHGE) and particular emphasis on cultural acceptability. A newly developed data envelopment analysis (DEA) diet model was applied to 4-d dietary record data among 184 healthy Japanese men and 185 women volunteers aged 21–69 years. Alternative diets were calculated as the linear combinations of observed diets. Firstly, for each individual, four modelled diets were calculated that maximised cultural acceptability (i.e. minimise dietary change from observed diet), maximised nutritional quality assessed by the Nutrient-Rich Food Index (NRF), minimised monetary diet costs or minimised diet-related GHGE. The final modelled diet combined all four indicators. In the first four models, the largest improvement was obtained for each targeted indicator separately, while relatively small improvements or unwanted changes were observed for other indicator. When all indicators were aimed to optimise, the NRF score and diet-related GHGE were improved by 8–13 % with the lower monetary cost than observed diets, although the percentage improvement was a bit smaller than the separate models. The final modelled diets demanded increased intakes for whole grains, fruits, milk/cream/yogurt, legumes/nuts, and decreased intakes for red and processed meat, sugar/confectioneries, alcoholic and sweetened beverages, and seasonings in both sexes. In conclusion, more sustainable dietary patterns considering several indicators are possible for Japanese, while total improvement is moderate due to trade-offs between indicators and methodological limitation of DEA diet model.

The present paper aims to contribute to the contentious debate regarding the role of meat as part of a sustainable diet. It uses secondary data to examine the patterns of meat consumption across the globe, and drawing on academic and grey literature, it outlines some of the policy, market and social trends and issues influencing demand and supply of meat. It also presents an overview of the scientific evidence base regarding the pros and cons of meat consumption. The results show that consumption patterns are not homogeneous globally, nor across meat types, with overall meat consumption increasing strongly in developing countries but stagnating in developed countries, and demand for poultry increasing in most regions in contrast to beef. They also illustrate the evolving impact of factors such as income on consumption and the increasing impact of non-economic factors, such as social and policy influences relating to health and the environment, on food choice behaviours, to the extent that such behaviours are increasingly entering a moral space. Given the solid scientific evidence that simultaneously substantiates arguments to increase and decrease meat consumption, it is clear that dietary recommendations need to be context-specific. An important part of the context is the strategies being pursued by researchers and supply chain actors, from farmers through to processors, retailers and food service operators, to improve the sustainability credentials of livestock production. As new evidence emerges from such initiatives, the context will change which means that dietary guidelines will require continuous review.

High cost of nutritious foods and eating out of home (OH) might be barriers to healthy and sustainable diets. We examined adherence to Dietary Approaches to Stop Hypertension (DASH), EAT–Lancet reference diet (EAT) and Mediterranean diet score (MDS) and the associations with dietary cost and eating OH. We evaluated cross-sectional data from single multiple-pass 24-h diet recalls from 289 young adults (18–24 years) in Tirana, Albania. Dietary cost (in Albanian Lek (ALL)) was estimated by matching food consumption data with retail prices from local fast-food chains, supermarkets, restaurants and food vendors. Poisson regression was fitted to models that included DASH, EAT and MDS as dependent variables to assess associations between healthy sustainable diet indicators and dietary cost and eating OH. Adjusted models were controlled for BMI, sex and total energy intake (kJ) using the residual method. Our findings indicate relatively poor adherence to healthy and sustainable dietary patterns among young men and women in Albania. Furthermore, better adherence to DASH, EAT or MDS was not associated with dietary cost (per 100 ALL; range incidence rate ratios (IRR): 0·97–1·00; all (un-)adjusted P > 0·05). Nonetheless, eating OH was related to lower adherence to DASH (IRR: 0·79; P = 0·003) and MDS (IRR: 0·69; P < 0·001). In conclusion, adherence to health and sustainable dietary patterns was poor and not differentiated by cost, but rather source of foods (i.e. OH or at home). Further research on the potential public and environmental health effects of these findings is warranted in Albania.