We analyzed the cost and environmental impact of current, healthy and sustainable diets in the Brazilian population based on a standardized protocol developed by INFORMAS. Our results highlight the significant influence of the nutritional quality of diets on economic and environmental aspects. Notably, we observed that in comparison with current diets, BDG diets exhibited a more favorable cost profile, suggesting that adhering to BDG recommendations can yield financial benefits for the Brazilian population. However, EAT-Lancet diets had slightly higher costs than the current diets. Our study identified a clear association between dietary choices and environmental impact. Current diets were associated with the highest CF and WF. The positive correlation between environmental impact indicators and cost further highlights the interplay between diet, sustainability, and economics, where greater environmental impact was associated with higher costs for all diets, especially those associated with current diets.

Several countries already monitor the costs associated with healthier and more sustainable diets on a regular basis, highlighting the need for interventions that enhance access to nutritious foods while mitigating planetary impact [20, 27–31]. A 2011 study analyzing food price data from 159 countries assessed the economic impact of the EAT-Lancet diet [27]. The average daily cost of the EAT-Lancet diet (2,503 kcal/day) was US$2.84 across all countries, with higher costs in high-income countries (US$2.66) than in low-income countries (US$2.42). Using linear programming, a nutritionally balanced reference diet was found to cost 1.6 times less than the EAT-Lancet diet. The latter was deemed unaffordable for many families, particularly in low-income countries [27]. The cost of healthier diets disproportionately affects lower socioeconomic groups (SEGs) [27].

In a 2011/2012 Australian study, the cost of healthy diets aligned with the Australian Dietary Guidelines was investigated across income quintiles [31]. Overall, the cost of the healthiest diet was lower than the usual diet across all quintiles. For the usual diet there was a significant budget allocation to UPF across quintiles and higher costs of alcoholic beverages in the highest quintile, while healthy foods and beverages had a greater impact on the lowest quintiles [31].

Some studies in middle- and high-income countries, following the INFORMAS protocol, have examined dietary costs [20, 28–30]. In Mexico, both healthy and sustainable diets were cheaper than the current isocaloric diet [28]. Conversely, in New Zealand [20, 29] and Argentina [30], healthy [20, 29, 30] and sustainable [29] diets tended to be more expensive than current diets. In New Zealand, studies have examined scenarios with [20] and without [29] alcoholic beverages and takeaways, both showing higher costs for current diets. In Argentina, although alcoholic beverages were included in current diet calculations, their impact on cost was minor compared to fruits, vegetables, and meats, which also contributed significantly to healthy diets [30].

In our study, the cost finding is mostly explained by the reduction of UPF and red meat in the BDG and EAT-Lancet diets (BDG diets are lower in discretionary foods and red meat in comparison to current diets, while EAT-Lancet diets have no discretionary foods or sweetened beverages and have the lowest amount of red meat). Replacing these groups with fresh vegetables, grains and starchy vegetables imposes an economic benefit in the Brazilian price scenario. Although fruits and vegetables are recognized for their high cost per calorie, grains and pulses tend to be low-cost items per kg, resulting in an overall reduction in cost, a trend akin to findings in other countries [27, 28]. Even though the greater proportion of fruits and vegetables present in the EAT-Lancet diets had an impact on the cost of the diet, we still observed an economic benefit due to the lower amounts of red meat and UPF in this diet.

However, although fresh and minimally processed foods were cheaper than UPF in our price scenario (2017/2018 data), projections suggest that the reverse will be true in 2026 [10] or even sooner, as a deleterious effect of the Covid-19 pandemic [11]. In 2022, due to the effects of the Covid-19 pandemic, the foods that had the biggest impact on food cost were tubers, roots and vegetables, fruits, flour, and pasta, milk, and dairy products [13].

In addition to food costs, our study also assessed the environmental impact of diets. Both the BDG and EAT-Lancet diets, as expected, demonstrated reduced environmental impacts, indicating that aligning dietary choices with health and sustainability goals can yield mutually beneficial outcomes. Moreover, the observed correlation between higher environmental impact and higher dietary costs, which is particularly evident in current diets, underscores it is critical to promote more sustainable eating habits.

Given the approximate cost between current and EAT-Lancet diets, along with the environmentally advantageous aspects of the latter, advocating the adoption of more sustainable diets seems to be a good choice. This parallel is evident in a study conducted in New Zealand, examining diet costs and their connection to GHG emissions [29]. Like our findings in Brazil, this New Zealand study revealed a direct relationship between rising dietary costs and greater climate impacts, particularly within the context of current diets [29]. This relationship holds true within each dietary pattern as well, where an increase in climate impact corresponds to an increase in diet costs [29]. Furthermore, even with the somewhat high cost of the EAT-Lancet diet, which is far from the reality of food consumption in the Brazilian population, we reinforce that choices based on BDG, in addition to presenting a lower cost, have a characteristic closer to the eating habits of the Brazilian population [23], thus being more accessible and making it possible to be a first step toward change.

A study in Brazil using 2008/2009 data employed linear optimization techniques to create culturally acceptable, healthier diets targeted at reducing GHG emissions, comparing them with the cost and sustainability of the current diet (2000 kcal) [32]. The modeled healthier diet showed lower emissions (3.93 kgCO2eq) but higher cost (US$2.67) compared to the current diet (4.40 kgCO2eq; US$2.16) [32]. Adhering to these dietary recommendations would increase overall diet expenditure by 14 to 24%, mainly by promoting higher fruit and vegetable consumption [32]. Another study with 2017/2018 data found that reducing beef and UPF purchases combined could lead to a 21.1% reduction of the CF and a 20.0% reduction in the WF [33].

In this sense, it is imperative to recognize that while BDG and EAT-Lancet diets have reduced environmental impacts, widespread adoption may require targeted policy interventions, educational initiatives, and infrastructural support, reflecting the need for cultural shifts in dietary habits. Especially when we consider the current diet of the Brazilian population, with low consumption of fruits and vegetables, moderate consumption of red meat and dairy and ultra-processed products [33]. Furthermore, Brazil has seen a progressive increase in UPF and animal protein consumption over time [16]. Studies suggest reducing the intake of these products for better health and environmental outcomes [5, 34].

Through a more comprehensive analysis aimed at identifying the effect of environmental impact on the costs of different diet types, we observed that adopting BDG diets can effectively reduce climate impacts while incurring lower costs. Moreover, adhering to recommendations centered on healthier and more sustainable diets, such as the EAT-Lancet guidelines, can be achieved at a cost similar to that of current diets. It is important to underscore that, with the utilization of more current and extensive data regarding food prices in the country, we have noted higher emissions in the environmental impact indicators than what was observed in studies employing earlier data [32, 35]. This value significantly exceeds the recommended estimates for mitigating climate impacts [35], thereby emphasizing the necessity for strategic interventions to rectify this situation.

Reconfiguring health-focused and sustainable food systems requires coordinated policies across sectors such as agriculture, health, education, and the environment. Multisectoral initiatives are crucial at the local, national, and international levels to promote sustainable production and improve planetary and population health [3]. To this end, policies and initiatives aligned with the Sustainable Development Goals (SDGs) outlined in the 2030 Agenda play a pivotal role [36].

Dietary patterns that follow the nutritional guidelines put forth by the WHO [3] and the BDG [8], which advocate for reduced consumption of UPFs and sweetened beverages, along with an increased intake of natural and minimally processed plant-based foods have the potential to decrease the environmental impact of diets [3]. Furthermore, it is necessary to consider clearer recommendations to reduce the consumption of red meat and animal-based products in BDG. Complementary strategies such as minimizing the use of plastics and plastic-derived materials in food packaging, opting for locally sourced and seasonal foods, and reducing food waste, also yield favorable environmental outcomes [3]. Financial incentives, such as subsidies for fresh produce, as well as the imposition of taxes on UPFs, can represent a pertinent economic intervention, fostering the adoption of healthier, sustainable diets and mitigating their associated costs [34]. By intertwining these multidimensional strategies, a comprehensive approach can be developed to guide individuals and societies toward more sustainable and health-conscious dietary patterns.

Limitations should be noted for a better interpretation of our findings. The comparison of the cost of the diets considered only the cost associated with the food items, without considering the costs associated with preparing and obtaining them. The environmental impact on each food was obtained by an average of data from other countries and studies [17], which may vary according to the region and type of food purchase. Another limitation is that the price data used were from 2018, the last food acquisition survey available in the country. Given the changes in food prices observed more recently, especially due to the Covid-19 Pandemic and economic changes in Brazil [11, 13], it is believed that the scenario may have worsened in relation to the higher cost of natural and minimally processed foods, reinforcing the scenario of the differences found between the costs of diets. It should also be noted that the HBS data refer to household purchases, and that an important part of people’s consumption is related to consumption outside the home. However, the use of total nutrients established by international references [24–26] made it possible to analyze the appropriate total calories for each individual. Furthermore, in the application of diet modeling, certain food groups did not meet the established nutrient thresholds. This discrepancy may have impacted the final cost of the diet.