Diet composition and food quality have direct effects on human health; however, the indirect health effects caused by environmental change associated with the processes of producing food are less recognized. As national dietary guidelines provide advice for a healthy diet, they must consider both direct and indirect health consequences of nutritional recommendations [1].

In April 2016, the United Nations Decade of Action on Nutrition (2016–2025) was established to recognize the importance of ending all forms of malnutrition, with policies and programs aimed at developing sustainable food systems and promoting healthy dietary practices [2]. In particular, the objectives of the Decade of Action on Nutrition are to support the fulfilment of the Second International Conference on Nutrition (ICN2) commitments [3] and achieve Global Nutrition and diet-related Non-Communicable Disease (NCD) targets by 2025 [4], as well as to contribute to achieving the Sustainable Development Goals (SDGs) by 2030 [5].

Current food systems need to be reshaped to provide health-promoting quality products with a low environmental impact [6]. Coherent actions and innovative food systems are needed to ensure access to sustainable, balanced and healthy diets for all [7]. The quality and sustainability of food systems are also central to fighting against NCDs, considering that isolated interventions have had a limited impact [8]. Efficient approaches include actions for sustainable food systems that promote healthy and safe diets, with national policies integrating nutrition and food safety objectives into food and agriculture policies; strengthening local food production and processing, especially by smallholder and family farmers and developing guidelines on food safety and quality [5]. A healthy diet can be a good entry point for individual and collective action aimed to improve the ability of food systems to provide sufficient affordable and nutritious foods and preserve biodiversity at the production level [9].

As reported by Rossi et al., 2022 [18], one of the novelties of the fourth revision of the IDGs was the inclusion of a chapter with recommendations on the sustainability of food choices. The objective of the sustainability chapter—directive 13 of the Italian guidelines—was the fostering of food choices aimed to promote both human health and environmental protection. The development of the sustainability recommendations was carried out, based on published evidence, statements and data supported by the consensus literature. A multistep approach was adopted with an initial literature study including the use of peer-reviewed papers and technical reports from intergovernmental agencies, non-governmental organisations and private bodies to prepare background documentation. The background scientific dossier provided the emerging issues on sustainability used for the preparation of the sustainability chapter of the guidelines. The second phase of directive 13 development involved discussions about the background document by the coordination committee to define how the main issues could be translated into the guideline addressed to consumers. The third phase was the preparation of the guidelines and their final approval for consensus.

The IDGs’ sustainability chapter recommendations on food selection discourages items with a two-fold negative impact: on health and the environment. The recommendation is to reduce processed meat and red meat, in favor of poultry, which is less costly and has a smaller environmental impact, and vegetable sources of protein, such as legumes. Regarding fish, the advice is to include a diet of small fish from the Mediterranean Sea, such as anchovies, sardines, mackerel, etc., and reduce consumption of the generally preferred species, such as tuna, salmon, swordfish, etc., that are subject to exploitation and erosion. Consumption of fish from aquaculture is recommended as a strategy to preserve wild resources given the increased quality of farmed fish. As regards fruit and vegetables, the recommendation is to consume seasonal products, limiting the selection of varieties requiring the large use of external input for growing, such as fertilizing, artificial light and heating. It is also recommended to limit the consumption of overseas products.

Food loss and waste were largely addressed, as priority attention was given to these aspects in Italy since the approval of a dedicated law [20] in line with the international commitment to food loss and waste reduction and prevention [21]. Considering the IDGs’ targets, the recommendations were focused on consumers’ behaviors, providing advice on how to plan food purchases, to prepare and store food in light of waste reduction and prevention and as a strategy to save money. It was suggested to avoid buying more than needed, in order to keep food fresh and limit waste. Practical examples were given on how to re-utilize old ingredients or leftovers in new recipes. The availability and economic sustainability of nutritional foods were addressed, providing recommendations for a healthy diet that was also affordable in monetary terms. Examples of ingredients combining a high nutritional value and low cost, such as eggs, poultry, beans, milk and seasonal vegetables, were provided to help the dietary choices of consumers with limited monetary possibilities.

In 2019 [3], the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) developed the guiding principles around what constitutes sustainable healthy diets. The guiding principles for sustainable healthy diets are food-based, combine recommendations with environmental, social/cultural and economic sustainability, and need to be translated into clear, non-technical information and messaging to be used by governments and other actors in policy-making and communications. Although principles, such as breastfeeding and NCD had the potential to be treated in terms of sustainability, they were only considered in terms of health-promotion. Several guiding principles were considered only in terms of sustainability (e.g., biodiversity, food waste, packaging and cultural aspects of food choices). Three principles were not treated in the IDGs, namely processed foods, antibiotics and hormones for food production and gender issues. The reasons for the non-inclusion of these topics were varied. Food policy in Italy is not specifically addressed to discriminate between processed and non-processed foods, considering the nutritional profile as more relevant than the technological process of production. Further reflection on these aspects should be carried out with a better understanding of the impact and quantitative relevance of processed foods in the overall Italian diet. Antibiotics and hormones were merely hinted at in the safety chapter of the IDGs (directive n. 12), in consideration of the very strict legislation in Italy and Europe on the use of antibiotics and hormones banned since 2005 [22]. Gender aspects, in terms of equality and women’s participation in social life, were not treated in the IDGs, which only touched on aspects of changing nutrient requirements in the various female physiological life stages (e.g., pregnancy, lactation, menopause). This is a gap in the current IDGs that needs to be remedied in further revisions.

The treatment of sustainability in the framework of nutritional guidelines is an emerging issue and a relatively new topic since the FBDGs remain predominantly health-focused and often neglect the environmental aspects of diet. However, in the European region, a relevant part (20–30%) of the total environmental impacts of households are associated with food consumption and several initiatives claim that a change in the food systems can address sustainability aspects [23]. As reported by Cambeses-Franco et al., 2022 [24], the FOOD 2030 initiative, in line with the European Green Deal, farm to fork strategy and bio-economy strategy, embraces this transformation with the aim to promote sustainable healthy diets, circularity and resource efficiency, innovation and empowerment of communities. FOOD 2030 highlights that the FBDGs could be drivers for changing and promoting healthy, balanced and sustainable food habits [25].

The IDGs, to some extent, anticipated these general recommendations as their development began in 2013. During the preparation of the IDGs’ sustainability chapter, to avoid assumptions and to limit the bias of personal interpretation, particular attention was given to the selection of recommendations supported by the literature. In the development of recommendations, priority was given to actions possible at the consumer level over those proper to the productive system. The idea was to provide families and individuals with advice for daily choices to encourage behaviors combining the selection of food promoting health and environmental protection.

The IDGs is a consensus document resulting from acceptance by a large scientific and political community. A national task force was established with experts from universities, research bodies, scientific societies and consumer associations. In addition, the document was endorsed by the Ministries of Agriculture, Health, Environment and Education [26]. This revision, for the first time, included the contribution of the Ministry of Environment, which worked specifically on the sustainability chapter. The underlying idea of this involvement was to bring in a point of view to some extent separate to nutritional aspects, with the challenge of combining expertise in different fields. The added value of this multidisciplinary approach is related to the fact that dietary behavior is a strong determinant of food consumption, which represents a key lever for action to transform food systems and vice versa. The involvement of the Italian Ministry of Environment was important to provide recommendations and solutions for transition through a transdisciplinary and multi-level approach addressing the factors influencing dietary behavior and health, together with the environmental and socio-economic impacts of dietary patterns. Ministry of Environment technicians were included in the process of development of the IDGs’ sustainability chapter to approach the development of recommendations with a holistic method considering consumers’ dietary behaviors and food consumption as relevant components of the agri-food-systems able to influence food production. In Europe, the farm to fork strategy [27] and recent studies on an EU food system transition [28,29,30] have embraced this holistic method to avoid sectorial approaches that are limited in terms of objectives or partial sub-systems [31]. The Ministry of Environment’s contribution to directive 13 of the IDGs, concerned the Italian commitment to sustainable development strategies for the implementation of the 2030 Agenda. On the Ministry of Environment’s website, a page dedicated to this joint effort was created to highlight these efforts [32].

The inclusion of sustainability in the IDGs was the driving force behind a series of actions and research projects aimed at increasing the knowledge of the relationship between dietary habits, food consumption and sustainability aspects. The first step was the creation of a dataset merging food consumption data with environmental footprint data, in terms of GHGE emissions. The database of the national food consumption INRAN-SCAI 2005–2006 survey [33,34], linked with the Italian Food Composition Databases [35] and the Food Composition Database for Epidemiological Studies in Italy [36], was combined with the GHGE estimations, providing data on the kg CO₂ equivalent per each 100g of food items [37]. Through combined database modeling, it was demonstrated that only by aligning consumption with the IDGs’ recommendations would it be possible to achieve a reduction of 50% of GHGEs, with respect to the Italian adult population’s current dietary patterns [37]. The IDGs’ dietary advice derived from health and sustainability considerations, and the modeling results showed that the shift in Italian dietary habits, proposed in the IDGs, could result in more environmentally sustainable food consumption patterns. The high level of sustainability of the diet recommended in the IDGs was further demonstrated in the paper by Cambeses-Franco et al., 2022 [38], which compared the carbon footprint (kgCO2eq/person/day) and water footprint (L/person/day) of the planetary diet provided by the EAT-Lancet commission with the Spanish dietary pattern and the recommended dietary patterns resulting from the guidelines of Italy, the Netherlands, the Mediterranean region and America. The results highlighted the best environmental indicators, carbon footprint and water footprint, for the diet recommended in the IDGs. The modeling methodology was also used to demonstrate that among existing school catering menus, it would be possible to select recipes combining a low environmental impact with a high adherence to the IDGs’ recommendations [39,40].

The IDGs’ sustainability chapter largely addressed the topic of food waste, providing a set of recommendations to prevent and reduce food waste at the household level. In Italy, food waste prevention initiatives at the consumer level were linked to food behavior and consumption, and other aspects, such as the promotion of a varied, healthy and sustainable diet, as reported in the IDGs [41]. Since the publication of the IDGs’ sustainability chapter, connections between dietary habits and food waste behavior were further analyzed, showing that consumers who follow the IDGs’ recommendations tend to have a highly preventive attitude towards food waste [42,43].

One of the limitations of the Italian approach to the development of sustainability recommendations was that it was carried out without an evaluation of Italian consumers’ awareness of sustainability. A duly designed survey on this topic was carried out in 2022 on a representative sample of Italian consumers with an approved questionnaire to assess Italian consumers’ level of awareness of the environmental impact of food choices, with a specific focus on whether alternative protein to meat, even new generation, would be accepted by Italian consumers [44]. Italian consumers considered other factors (deforestation, use of cars, etc.) as much more relevant to sustainability than food consumption and eating habits [45]. The reduction of meat consumption was strongly recommended in the IDGs’ sustainability chapter. Currently, Italian consumers reported their willingness to replace meat with known foods considered as part of traditional consumption, such as legumes, eggs, fish, cheese and nuts. Moreover, respondents are much less likely to replace meat with novel foods such as, seitan, seaweed, tempeh, jellyfish and other meat substitutes. In addition, Italian consumers reported a strong resistance to the consumption of insects and synthetic meat. As a policy implication, this nationwide country representative assessment could also be used as a benchmark for developing specific recommendations, in consideration of the limits of the inclusion of sustainability in nutritional advice, and could contribute to the maximization of the capacity of the dietary guidelines, to create a healthy food environment [44,46].

Teschner et al., 2021 [47] reported that, besides the general agreement on the need for more sustainable diets, a definition of sustainable dietary recommendations for consumers is still lacking and this is relevant in the development of the dietary guidelines. Consumers’ understanding of sustainability is one aspect of the development of the relative recommendations and their inclusion in the FBDGs. A codified methodology for sustainability was still not available for inclusion in the dietary guidelines, however several experiments are reported that used the optimization methodology. A linear programming analysis is a mathematical approach that can be used to model dietary consumption, based on current dietary patterns with the inclusion of sustainability indicators. The development of the FBDGs with diet optimization has the advantage of controlling the variables and also including sustainability items as elements of the model [48,49], evaluating the complexity of the overall food consumption pattern [50]. Schäfer et al., 2021 [51] reported the results of the optimization methodology to develop the German FBDGs, that included sustainability recommendations, and they considered the flexibility of the mathematical model useful to identify dietary changes in Germany that would take into account diet-health relations, environmental impact and cultural acceptability. Another interesting trial concerning the optimization of dietary patterns to develop the FBDGs that simultaneously meet recommendations for food groups and nutrients and limit, at maximum, the foods with a high environmental impact, was carried out in the Netherlands, combining the optimization of dietary patterns with recommendations, based on expert judgment [52].

In Italy, as previously reported, the optimization of food consumption was used to demonstrate a reduction in the environmental impact of the recommended diet without the exclusion of any food group, including red meat and milk [37]. Optimization could be a suitable approach to guide the development of recommendations aimed at improving the sustainability of diets considering all of the characteristics of diets, to find solutions for nutritional, environmental, and economic aspects mitigating any possible incompatibilities among dimensions [53]. However, an important aspect that needs to be taken into account in the FBDGs’ development, is the cultural acceptability of foods as part of the sustainability of the diet. The selection of sociocultural indicators is subjective and depends on the availability of data, which represents a limit for the application of the optimization approach. As demonstrated in the abovementioned work on consumers’ acceptability in Italy of meat substitutes, a recommendation that includes an “exotic” meat alternative would be unlikely to be accepted, even if it were the best solution in terms of environmental impact [45]. As reported by Perignon and Darmon (2022), the identification of indicators for assessing the cultural acceptability and the availability of reliable data on these aspects are difficult and challenging [53].

The general recommendations for developing DGs that could be proposed on the basis of the first experience carried out in Italy would be a combined approach of the optimization of food consumption, coupled with consumer acceptance studies, at least for particularly innovative topics.

The main limitation of the IDGs is related to the existing gap between dietary recommendations and actual consumer behavior, indicating a generally poor compliance with the IDGs [18]. In Italy, a detailed plan for developing strategies to assist behavior change is still lacking and this is particularly true for recommendations on a sustainable dietary pattern that have only recently been developed [18]. On this topic, it is interesting to note the outcome of the evaluation of the food sustainability index (FSI) measuring the sustainability of food systems in countries around three key pillars: food loss and waste, sustainable agriculture and nutritional challenges. One of the aspects with the highest score in the nutritional pillar is to have dietary guidelines that have been updated in the past 5 years and explicitly mention sustainability or the environment [54]. In the 2021 data, Italy ranked 16th out of the 78 countries included in the evaluation, with a very high level for food loss and waste ranking at 2/78. However, in terms of sustainable agriculture (ranked 53/78) and nutritional challenges (32/78), the situation is far from optimal. The nutritional challenges of this evaluation deserve comment in consideration of the fact that besides Italy’s high scores relating to a healthy life expectancy, low nutrient deficiencies and affordability of a healthy and sustainable diet, critical aspects are reported for physical activity, the prevalence of over-nourishment, the environmental impact of dietary patterns, diet composition and policy nutritional response. It should be pointed out that the top performers in the nutritional challenges’ pillar include the EU countries of Sweden, Denmark, France, the Netherlands, Luxembourg and the United Kingdom, which are already developing policies to strengthen the link between diet and sustainability. The FSI has been evaluated periodically since 2016. Keeping trace of this index could be a way to monitor the impact of ongoing campaigns promoting sustainability in food choices, including the IDGs’ recommendations.

The 2030 Agenda for Sustainable Development, adopted by all United Nations member states in 2015, is a common cooperation framework to promote sustainable development. The Agenda is articulated in 17 Sustainable Development Goals (SDGs) that include actions and measurable targets to improve health and education, reduce inequality, promote economic growth, address climate change and the preservation of oceans and forests [5]. The SDGs have a transversal nature and are applicable in developed and developing countries. SDG 2 (‘end hunger, achieve food security and improved nutrition and promote sustainable agriculture’) is the only SDG that mentions ‘nutrition’, which is, however, directly or indirectly an important cross-cutting issue in all SDGs, [19]. The IDGs can contribute to achieving the Sustainable Development Goals (SDGs) by the promotion of a dietary pattern protective of human health and the environment. According to Grosso et al., (2020) [19], there are multiple direct and indirect pathways by which policies to promote a healthy diet for people and the environment support the 17 SDGs. The potential contribution of the IDGs’ directive 13 to the achievement of SDGs is an interesting exercise to evaluate how far Italian recommendations on sustainability reach the pre-fixed objectives of the 2030 Agenda identifying the areas of improvement that could be addressed in the implementation and dissemination activities of the IDGs. The strengths and weaknesses of the IDGs’ sustainability recommendations supporting the SDGs were reported.