The carbon footprint of dietary guidelines around the world: a seven country modeling study

Mexican national dietary guidelines promote less costly and environmentally sustainable diets

The 2023 Mexican Healthy and Sustainable Dietary Guidelines (HSDG 2023) were developed to include all dimensions of sustainability. Here we compare the environmental impact and cost of diets based on the HSDG 2023, current diets and the Mexican-adapted EAT healthy reference diet. Diets following HSDG 2023 are 21% less expensive, require 30% less land to be produced and have 34% less carbon emissions than current diets-particularly in Mexico City and other urban areas with higher prevalence of Westernized diets. This is driven by reduced animal-source food, especially red meat, and ultra-processed foods. In south-rural areas, the water footprint and cost of diets following HSDG 2023 were higher than those of current diets owing to increased intake of nuts, fruits and vegetables not offset by lower meat consumption (which is already close to recommendations). Diet environmental impact and cost could be further reduced with the Mexican-adapted EAT healthy reference diet compared with the HSDG 2023.

Augmenting the National Nutrition Data System to Promote Diet Sustainability Analyses

Research on sustainable diets has become an important and growing area of the nutrition field, but recent studies have pointed to a lack of sustainability metrics and methods that are hindering research and policy progress. To fill this gap, the White House National Strategy on Hunger, Nutrition, and Health calls for increased funding to improve metrics, data collection, and research to address all domains of sustainability, which include nutrition/health, economic, environmental, and social domains. Commodity recipe databases, such as the Food Commodity Intake Database (FCID), are important tools for conducting diet sustainability analyses because they translate mixed dishes from dietary surveys, such as the National Health and Nutrition Examination Survey (NHANES), into commodity ingredients. These ingredients have been linked to data on environmental impacts and economic costs from other databases, thus facilitating collaboration between nutrition researchers, environmental scientists, economists, and others. These linkages cannot be made with other components of the national nutrition data system, such as the Food Patterns Equivalents Database (FPED), because the disaggregated food groups from them are not relevant for examining environmental impacts. Although the NHANES is conducted on an ongoing basis, and FPED is continually updated, the FCID has not been officially updated since 2010. This severely limits advancements in sustainability research and related policy analyses. In this commentary, we argue that the federal government should promote this diet sustainability work by integrating a commodity recipe database into the national nutrition data system, and updating it on a regular basis, as it does with other component databases.

Mixed diets can meet nutrient requirements with lower carbon footprints

Achieving sustainable dietary change is essential for safeguarding human and environmental health. However, dietary recommendations based on broad food groups may not accurately reflect real-world realities because individuals select and consume dishes with multiple food items influenced by diverse context-specific factors. Therefore, here we explored the sustainability trade-offs of dietary choices at the dish level through an optimization modeling approach tested in Japan. We estimated the nutritional quality, price, and carbon footprint of major Japanese dishes and examined 16 dietary scenarios to identify options that meet the nutritional requirements and minimize carbon footprint. Overall, mixed diets contain more combinations of dishes that meet nutritional requirements with lower carbon footprints compared to more restrictive dietary scenarios. We argue that the approach developed here enables a better understanding of dietary trade-offs, complements existing methods, and helps identify sustainable diets by offering nuanced information at the national and sub-national levels.

Commercial weight-loss diets, greenhouse gas emissions and freshwater consumption

BACKGROUND

Weight-loss attempts are widespread in the United States, with many using commercial weight-loss diet plans for guidance and support. Accordingly, dietary suggestions within these plans influence the nation's food-related environmental footprint.

METHODS

We modelled United States (US) per capita greenhouse gas emissions (GHGe) and water footprints associated with seven commercial weight-loss diets, the US baseline, and selected other dietary patterns. We characterised consumption in commercial weight-loss diets both via modelling from provided guidelines and based on specific foods in 1-week meal plans. Cradle-to-farmgate GHGe and water footprints were assessed using a previously developed model. GHGe results were compared to the EAT-Lancet 2050 target. Water footprints were compared to the US baseline.

RESULTS

Weight-loss diets had GHGe footprints on average 4.4 times the EAT-Lancet target recommended for planetary health (range: 2.4-8.5 times). Bovine meat was by far the largest contributor of GHGe in most diets that included it. Three commercial diets had water footprints above the US baseline. Low caloric intake in some diets compensated for the relative increases in GHGe- and water-intensive foods.

CONCLUSIONS

Dietary patterns suggested by marketing materials and guidelines from commercial weight-loss diets can have high GHGe and water footprints, particularly if caloric limits are exceeded. Commercial diet plan guidance can be altered to support planetary and individual health, including describing what dietary patterns can jointly support environmental sustainability and weight loss.

Healthiness and environmental impact of dinner recipes vary widely across developed countries

Contrary to food ingredients, little is known about recipes' healthiness or environmental impact. Here we examine 600 dinner recipes from Norway, the UK and the USA retrieved from cookbooks and the Internet. Recipe healthiness was assessed by adherence to dietary guidelines and aggregate health indicators based on front-of-pack nutrient labels, while environmental impact was assessed through greenhouse gas emissions and land use. Our results reveal that recipe healthiness strongly depends on the healthiness indicator used, with more than 70% of the recipes being classified as healthy for at least one front-of-pack label, but less than 1% comply with all dietary guidelines. All healthiness indicators correlated positively with each other and negatively with environmental impact. Recipes from the USA, found to use more red meat, have a higher environmental impact than those from Norway and the UK.

Popular diets as selected by adults in the United States show wide variation in carbon footprints and diet quality

BACKGROUND

Carbon footprints of vegetarian, pescatarian, and other popular diets have been studied previously, but mostly as idealized versions modeled to meet dietary recommendations. Less is known about the footprints of popular diets as they are consumed by US adults, and thus the potential trade-offs with diet quality for free-living individuals.

OBJECTIVES

This study estimated the carbon footprint and diet quality of popular diets as selected by a nationally representative sample of US consumers, including the recently trending keto- and paleo-style diets.

METHODS

The 2005-2010 NHANES 24-h recall data were used to categorize individual adult diets (n = 16,412) into 6 types: vegan, vegetarian, pescatarian, paleo, keto, and all other diets, referred to here as omnivore diets. Average daily greenhouse gas emissions in kilograms of carbon dioxide equivalents per 1000 kcal (kg CO2-eq/1000 kcal) were calculated for each diet by matching our previously developed database to NHANES individual diet data. Diet quality was determined using the Healthy Eating Index (HEI) and the Alternate Healthy Eating Index. Survey-weighted ordinary least-squares regression was used to assess mean differences in diets.

RESULTS

The average carbon footprints of vegan (0.69 ± 0.05 kg CO2-eq/1000 kcal) and vegetarian (1.16 ± 0.02) diets were lower (P < 0.05) than those of the pescatarian (1.66 ± 0.04), omnivore (2.23 ± 0.01), paleo (2.62 ± 0.33), or keto (2.91 ± 0.27) diets. Mean HEI scores were highest for pescatarian diets (58.76 ± 0.79) and higher (P < 0.05) for vegetarian (51.89 ± 0.74) than for omnivore (48.92 ± 0.33) or keto (43.69 ± 1.61) diets.

CONCLUSIONS

Our results highlight the nuances when evaluating the nutritional quality of diets and their carbon footprints. On average, pescatarian diets may be the healthiest, but plant-based diets have lower carbon footprints than other popular diets, including keto- and paleo-style diets.

Nutrient-sensitive approach for sustainability assessment of Australian macronutrient dietary recommendations

BACKGROUND

Dietary guidelines that form the basis for food and nutrition policies in most countries are focused mainly on the social dimensions of health. Efforts are needed to incorporate environmental and economic sustainability. As the dietary guidelines are formulated based on nutrition principles, understanding the sustainability of dietary guidelines in relation to nutrients could support the better incorporation of environmental and economic sustainability aspects into dietary guidelines.

OBJECTIVES

This study examines and demonstrates the potential of integrating an input-output analysis with nutritional geometry to assess the sustainability of the Australian macronutrient dietary guidelines (AMDR) relating to macronutrients.

METHODS

We used daily dietary intake data of 5345 Australian adults from the most recent Australian Nutrient and Physical Activity Survey 2011-2012 and an input-output database for the Australian economy to quantify the environmental and economic impacts associated with dietary intake. Then, we examined the associations between environmental and economic impacts and dietary macronutrient composition using a multidimensional nutritional geometry representation. Thereafter, we assessed the sustainability of the AMDR regarding its alignment with key environmental and economic outcomes.

RESULTS

We found that diets adhering to the AMDR were associated with moderately high greenhouse gas emissions, water use, cost of dietary energy, and the contribution to wages and salaries of Australians. However, only about 20.42% of respondents adhered to the AMDR. Furthermore, high-plant protein diets adhering to the lower limit of recommended protein intake in the AMDR were associated with low environmental impacts and high incomes.

CONCLUSIONS

We conclude that encouraging consumers to adhere to the lower limit of the recommended intake of proteins and meeting the protein requirement through protein-dense plant sources could improve dietary environmental and economic sustainability in Australia. Our findings provide a means of understanding the sustainability of dietary recommendations concerning macronutrients for any country where input-output databases are available.

Environmental advantages of coproducing beef meat in dairy systems

Beef meat, one of the more environmentally costly animal-based foods, can be produced in two general ways, as the main product on specialised farms or as a co-product on dairy farms. In this study, two cases (a semi-confinement dairy farm (A) and a pasture-based dairy farm (B)) have been analysed by means of LCA to evaluate the environmental impacts associated with the coproduction of beef meat. In both cases, purchased feed production was found to be the main cause of environmental impacts in most of the categories considered. Additionally, cow emissions to air were the main contributor for the global warming category. Comparing the two dairy systems, notably lower environmental impacts were obtained for B in 13 of the 18 categories analysed. Regarding CF, 8.10 and 8.88 kg CO₂eq/kg LW were obtained for A and B, respectively. These CF values were within the wide range found in the literature for beef meat (1.2-42.6 kg CO₂eq/kg LW). Beef calves and cull cows are an important output of dairy farming, so that coproduction enables milk and meat with lower CF and associated environmental impacts to be obtained. In addition, the variability of the data found in literature and the lack of LCA studies based on real data for beef meat coproduced on dairy farms evidence the importance of in-depth study of this interesting topic.

A Global Analysis of National Dietary Guidelines on Plant-Based Diets and Substitutions for Animal-Based Foods

Discussing plant-based diets and substitutions for animal-based foods in food-based dietary guidelines (FBDGs) can be a key step in making dietary recommendations more sustainable and healthy as well as more inclusive. The existing large-scale evaluations of FBDGs do not assess whether and to what extent countries cover the broad spectrum of plant-based diets and have policy positions on vegetarian diets, including vegan diets, and whether they mention specific plant-based alternatives to milk, dairy products, and meat. The main aim of this state-of-the-art review was to determine whether and how FBDGs provide such information. An overall 95 guidelines and 100 corresponding countries were assessed via an exploratory sequential mixed method. This involved qualitative explorative content analysis of the guidelines, followed by hierarchical cluster analysis. Furthermore, the Balanced Food Choice Index (BFCI) was constructed, which measures the extent to which FBDGs provide recommendations that cover the broad spectrum of plant-based diets, with some or no animal-based products. To explore the correlations between FBDGs' recommendations and ecological and economic country characteristics, ordinary least squares regression was used. It was found that most countries do not provide information to their citizens that cover the broad spectrum of plant-based diets, as indicated by the mean score of the BFCI (33.58 of 100 points). A total of 38 guidelines (40%) contain a position on vegetarian diets. Nearly half (45%) of all FBDGs already mention plant-based alternatives to meat or animal milk. The regressions showed that the BFCI correlates positively with countries' ecological efforts and negatively with the importance of animal-based products in their economies. This study demonstrates considerable information insufficiency in current FBDGs worldwide. FBDGs should provide recommendations for the broad spectrum of plant-based diets and balance the ethical, ecological, religious, and economic aspects that play a role in people's food choice.

Basics of Sustainable Diets and Tools for Assessing Dietary Sustainability: A Primer for Researchers and Policy Actors

Climate change can have economic consequences, affecting the nutritional intake of populations and increasing food insecurity, as it negatively affects diet quality parameters. One way to mitigate these consequences is to change the way we produce and consume our food. A healthy and sustainable diet aims to promote and achieve the physical, mental, and social well-being of the populations at all life stages, while protecting and safeguarding the resources of the planet and preserving biodiversity. Over the past few years, several indexes have been developed to evaluate dietary sustainability, most of them based on the EAT-Lancet reference diet. The present review explains the problems that arise in human nutrition as a result of climate change and presents currently available diet sustainability indexes and their applications and limitations, in an effort to aid researchers and policy actors in identifying aspects that need improvement in the development of relevant indexes. Overall, great heterogeneity exists among the indicators included in the available indexes and their methodology. Furthermore, many indexes do not adequately account for the diets’ environmental impact, whereas others fall short in the economic impact domain, or the ethical aspects of sustainability. The present review reveals that the design of one environmentally friendly diet that is appropriate for all cultures, populations, patients, and geographic locations is a difficult task. For this, the development of sustainable and healthy diet recommendations that are region-specific and culturally specific, and simultaneously encompass all aspects of sustainability, is required.

Is high adaptation to the Mediterranean diet effective in increasing ecological footprint awareness? A cross-sectional study from Turkey

BACKGROUND

The effect of diet type on sustainable environment is known. It is important to understand the adaptation of individuals with high ecological footprint awareness to the Mediterranean type diet, especially under the assumption that the Mediterranean diet will reduce the ecological footprint. In the study, it is aimed to examine the relationship between the level of adherence to the Mediterranean diet and Ecological Footprint awareness of adults.

RESULTS

The sample of the study consisted of 395 individuals with a mean age of 26.2 ± 8.7 years: 293 females (74.2%) and 102 males (25.8%). As the Mediterranean Diet Adherence Scale (MDAS) score of individuals increased, the Ecological Footprint Awareness Scale score also increased. Similarly, a positive correlation was found between the participants' MDAS score and the awareness of food (r = 0.157; P = 0.002), energy (r = 0.133; P = 0.008), waste (r = 0.149; P = 0.003) and water consumption (r = 0.101; P = 0.045), which are sub-factors of the Ecological Footprint Awareness Scale.

CONCLUSION

As far as is known, this cross-sectional study is one of the first studies on compliance with the Mediterranean diet and awareness of the ecological footprint. The findings of the study show that as individuals' compliance with the Mediterranean diet increases, their awareness of their ecological footprint will also increase. To reach a conclusion on this issue, future studies should evaluate the relationship between adherence to the Mediterranean diet and awareness of food-environmental impact on different samples. © 2021 Society of Chemical Industry.

Diet Sustainability Analyses Can Be Improved With Updates to the Food Commodity Intake Database

Diet sustainability analyses inform policymaking decisions and provide clinicians and consumers with evidence-based information to make dietary changes. In the United States, the Food Commodity Intake Database (FCID) provides a crosswalk for integrating nationally representative data on food intake from the National Health and Nutrition Examination Survey (NHANES) with data on sustainability outcomes from other publicly available databases. However, FCID has not been updated since 2010 and does not link with contemporary NHANES data, which limits further advancements in sustainability research. This study fills this research gap by establishing novel linkages between FCID and NHANES 2011-2018, comparing daily per capita food intake with and without these linkages, and making these data publicly available for use by other researchers. To update FCID, two investigators independently established novel data linkages, a third investigator resolved discrepancies, and a fourth investigator audited linkages for accuracy. Dietary data were acquired from nearly 45,000 adults from 2001 to 2018, and food intake was compared between updated vs. non-updated FCID versions. Total food intake from 2011 to 2018 was 5-23% higher using the updated FCID compared to the non-updated version, and intake was over 100% higher in some years for some food categories including poultry, eggs, legumes, starchy vegetables, and tropical oils (P < 0.001 for all comparisons). Further efforts may be needed to create new food composition data to reflect new products and reformulations that enter the food supply over time. This study removes a barrier to further diet sustainability analyses by establishing a data crosswalk between contemporary NHANES and other publicly available databases on agricultural resource use, environmental impacts, and consumer food expenditures.

Carbon Footprint Reduction by Transitioning to a Diet Consistent with the Danish Climate-Friendly Dietary Guidelines: A Comparison of Different Carbon Footprint Databases

Dietary transitions are important for combating many of the environmental challenges humanity is facing today and reducing the global burden of disease. Different dietary patterns are associated with substantially different carbon footprints (CFs). This study aims to estimate the potential CF reduction on a transition from the current Danish diet to a plant-rich diet consistent with the Danish food-based dietary guidelines (FBDG) and to compare results obtained from the use of two different CF databases. Dietary intake data for adults aged 18-64 years from the national dietary survey 2011-2013 were used to calculate the CF of the current diet, and this was compared with the estimated CF of the plant-rich diet modelled for the FBDG. Calculations were carried out using an attributional life cycle assessment (LCA) database (AU-DTU data) and compared to calculations using a top-down hybrid consequential LCA database (BCD data). The transition from the current diet to the plant-rich diet showed a substantial estimated CF reduction of 31% with AU-DTU data, and a greater reduction with BCD data (43%). Ruminant meat reduction was the largest contributor to this CF reduction, especially with the use of BCD data, and other animal-based foods also contribute considerably to the CF reduction, especially with AU-DTU data. These results indicate that the choice of LCA methodology and CF database is important in estimation of dietary CF and for the development of guidelines to promote dietary change.

Food-Based Dietary Guidelines and Protein Quality Definitions—Time to Move Forward and Encompass Mycoprotein?

Food-Based Dietary Guidelines (FBDG) lack uniformity globally, with the integration of protein food sources being highly variable. Protein guidance tends to be dichotomous, e.g., animal versus plant with other categories such as fungal proteins being overlooked. In 2019 the EAT Lancet Food in the Anthropocene report was a chief driver questioning the need to supply healthy diets from sustainable food systems. Some countries are developing FBDG that integrate these aspects, but these are quite often protracted, too subtle or misaligned with other countries, diluting the effects of meaningful global change. Protein quality metrics also underpin the dissemination of dietary guidance. However, for protein, these remain based on a food’s essential amino acid profile and digestibility scores, thus are nutritionally and physiologically centric. It has been proposed that this definition is becoming increasingly myopic from a wider societal perspective. Updated indices should include contemporary issues such as protein diversity and environmental outcomes. Taken together, there is opportunity for renewed thinking about both FBDG and protein quality definitions, with scope to include both health and environmental outcomes and need to move towards the concept of protein diversification.

A Food System Approach for Sustainable Food-Based Dietary Guidelines: An Exploratory Scenario Study on Dutch Animal Food Products

This study explores interconnections between food consumption and production of animal (by-)products in different food system scenarios within the scope of Dutch Food-Based Dietary Guidelines (FBDG). For this scenario study, a Microsoft Excel model was created that include seven scenarios with different quantities of eggs, milk, cheese, beef cattle, broilers, and pigs as input. Number of animals, intake of energy, animal protein, saturated fatty acids (SFAs), trans-fatty acids (TFAs), salt, greenhouse gas emissions (GHGEs), and land use (LU) were calculated and compared with current consumption and reference values. Based on the concept of eating the whole animal, every recommended lean, unprocessed portion of beef comes along with a non-recommended portion of beef (two portions for pork, 0.5 portion for broilers). The reference values for SFAs, TFAs, and salt were not exceeded if the intake of meat is limited to 410 g/week. The scenarios with recommended 450 mL semi-skimmed milk and 40 g/day low-fat cheese results in 36 g/day of butter as by-product, exceeding its acceptable intake three times. The near-vegetarian scenario with recommended amounts of eggs, milk, and cheese, includes only a portion of beef/calf per 6 days and a portion of chicken per 9 weeks as by-products. This scenario more than halves the GHGE and LU. Finally, the scenario that included the maximum recommended amounts of animal products is reachable with half the current size of Dutch livestock. This conceptual framework may be useful in the discussion on how future sustainable FBDG can incorporate a more food system-based approach.

Spatial-Temporal Footprints Assessment and Driving Mechanism of China Household Diet Based on CHNS

Food consumption is closely associated with resource consumption and environmental sustainability. An unreasonable dietary pattern would cause great pressure or damage to resources and the environment. It is particularly important to reduce the negative impact of household food consumption on resources and the environment while simultaneously ensuring people’s nutrient intake and health. This study applied the China Health and Nutrition Survey (CHNS) database to quantitatively study the spatial-temporal analysis of multiple footprints of household food consumption at multiple scales and explored the driving mechanism of the multiple footprints. The results showed that, except land footprint (LF), the other four types of footprints all decreased at varying degrees; the water footprint (WF), carbon footprint (CF), nitrogen footprint (NF) and energy footprint (EF) decreased by 18.24%, 17.82%, 12.03% and 20.36%, respectively, from 2000 to 2011; multiple footprints of food consumption of household in Guizhou was the highest among the 12 provinces involved in the study; this shows that resource consumption (water, energy and land resource) and environmental influences (CO₂ emissions and nitrogen emissions) brought by food consumption of per household in Guizhou are much greater than in other provinces, which has a negative influence on sustainable development; by analyzing the driving factors of multiple footprints, it is shown that nutrient intake, household attributes, educational level and health conditions were significantly correlated to multiple footprints. Among them, nutrient intake has greater impact on the multiple footprints of Chinese household food consumption. By comparing multiple footprints of different dietary patterns, it was found that the current Chinese dietary pattern would cause excessive resource consumption, which would bring more pressure on resources and the environment. Adjusting household living habits would possibly reverse the unsustainable situation, such as reducing the consumption of animal-derived foods and adjusting the dietary pattern of households with a higher educational level and income status. Chinese Dietary Guidelines 2016 has better sustainability; the promotion of this dietary pattern across the country would help China to relieve the pressure on resources and environment from the consumer side, promoting the realization of sustainable development.

Global Review of Dairy Recommendations in Food-Based Dietary Guidelines

At present, there are ~100 countries with national food-based dietary guidelines. While the intent of these guidelines is to inform national-level dietary recommendations, they also tie into global health and sustainable development initiatives, since diet and nutrition are linked to outcomes for all 17 United Nations Sustainable Development Goals. Therefore, key messaging in food-based dietary guidelines plays an important role in both national and global health efforts. However, this type of national-level dietary guidance is not standardized and varies considerably from country to country, and from food group to food group. The main objective of this review is to provide a novel look at dairy food group messaging within global food-based dietary guidelines, focusing specifically on nutrient-based and health-based messaging. Dairy-based messaging from 94 national food-based dietary guidelines was reviewed and grouped by region, with an emphasis on messaging regarding dairy's contribution to nutrients of public health concern for both underconsumption and overconsumption. The results showed that most nutrient-based dairy messaging relating to underconsumption was focused on calcium, followed by vitamin D, iodine, potassium, and protein; whereas messaging related to overconsumption was focused on saturated fat, added sugars, and salt. Health-based messaging specific to dairy food intake typically coalesced around three types of health outcomes: (1) bone, teeth, and muscle, (2) cardiometabolic, and (3) gut and immune. Although a fundamental concept of food-based dietary guidelines is to provide dietary guidance in a manner that is both “food-based,” and in the context of “dietary” patterns, most food-based dietary guidelines still express the health value of dairy foods (and potentially other foods groups) solely in terms of their nutrient content – and often times only in the context of a single nutrient (e.g., calcium).