Greenhouse gas emissions and energy use associated with production of individual self-selected US diets

Diet-related greenhouse gas emissions and major food contributors among Japanese adults: comparison of different calculation methods

OBJECTIVE

To develop a greenhouse gas emissions (GHGE) database for Japanese foods using three different approaches, compare the results of estimated diet-related GHGE and determine major food contributors among Japanese adults.

DESIGN

Cross-sectional. Three GHGE databases were developed: (1) a literature-based method including a literature review of life cycle assessment studies of Japanese foods and (2) production- and (3) consumption-based input-output tables (IOT)-applied methods using the Japanese IOT. All databases were linked to the Japanese food composition table and food consumption data. Diet-related GHGE was estimated based on each database and the 4-d dietary record data. Diet-related GHGE were compared in both total and food group level between the databases.

SETTING

Japan.

PARTICIPANTS

392 healthy adults aged 20-69 years.

RESULTS

The mean diet-related GHGE significantly differed according to the calculation methods: 4145 g CO2-equivalent (CO2-eq)/d by the literature-based method, 4031 g CO2-eq/d by the production-based method and 7392 g CO2-eq/d by the consumption-based IOT-applied methods. It significantly differed in food group level as well. Spearman's correlation coefficients between three methods ranged from 0·82 to 0·86. Irrespective of the methods, the top contributor to GHGE was meat (19·7-28·8 %) followed by fish and seafood (13·8-18·3 %).

CONCLUSIONS

Although the identified major food contributors to GHGE were comparable between the three methods, the estimated GHGE values significantly differed by calculation methods. This finding suggested that caution must be taken when interpreting the estimated diet-related GHGE values obtained using the different calculation methods of GHGE.

The cost of eating more sustainable diets: A nutritional and environmental diet optimisation study

We aim to identify the dietary changes to improve nutrition and reduce diet-related greenhouse gas emission (GHGE) simultaneously in Brazil, taking into account the heterogeneity in food habits and prices across the country. Food consumption and prices were obtained from two nationwide surveys (n = 55,970 households and 34,003 individuals). Linear programming models were performed to design optimised diets most resembling the observed diets, and meeting different sets of constraints: (i) nutritional, for preventing chronic diseases and meeting nutrient adequacy; (ii) socio-cultural: by respecting food preferences; and (iii) environmental: by reducing GHGE by steps of 10%. Moving toward a diet that meets nutritional recommendations led to a 14% to 24% cost increase and 10% to 27% GHGE reduction, depending on the stringency of the acceptability constraints. Stronger GHGE reductions were achievable (up to about 70%), with greater departure from the current diet, but not achieving calcium and potassium goals. Diet cost increment tended to be mitigated with GHGE reduction in most models, along with reductions in red meat, chicken, eggs, rice, and high-fat sugar sodium foods.

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

Background

Do the environmental impacts inherent in national food-based dietary guidelines (FBDG) vary around the world, and, if so, how? Most previous studies that consider this question focus on a single country or compare countries’ guidelines without controlling for differences in country-level consumption patterns. To address this gap, we model the carbon footprint of the dietary guidelines from seven different countries, examine the key contributors to this, and control for consumption differences between countries.

Methods

In this purposive sample, we obtained FBDG from national sources for Germany, India, the Netherlands, Oman, Thailand, Uruguay, and the United States. These were used to structure recommended diets using 6 food groups: protein foods, dairy, grains, fruits, vegetables, and oils/fats. To determine specific quantities of individual foods within these groups, we used data on food supplies available for human consumption for each country from the UN Food and Agriculture Organization’s food balance sheets. The greenhouse gas emissions (GHGE) used to produce the foods in these consumption patterns were linked from our own database, constructed from an exhaustive review of the life cycle assessment literature. All guidelines were scaled to a 2000-kcal diet.

Results

Daily recommended amounts of dairy foods ranged from a low of 118 ml/d for Oman to a high of 710 ml/d for the US. The GHGE associated with these two recommendations were 0.17 and 1.10 kg CO₂-eq/d, respectively. The GHGE associated with the protein food recommendations ranged from 0.03 kg CO₂-eq/d in India  to 1.84 kg CO₂-eq/d in the US, for recommended amounts of 75 g/d and 156 g/d, respectively. Overall, US recommendations had the highest carbon footprint at 3.83 kg CO₂-eq/d, 4.5 times that of the recommended diet for India, which had the smallest footprint. After controlling for country-level consumption patterns by applying the US consumption pattern to all countries, US recommendations were still the highest, 19% and 47% higher than those of the Netherlands and Germany, respectively.

Conclusions

Despite our common human biology, FBDG vary tremendously from one country to the next, as do the associated carbon footprints of these guidelines. Understanding the carbon footprints of different recommendations can assist in future decision-making to incorporate environmental sustainability in dietary guidance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-021-00669-6.

Human exposure assessment to potentially toxic elements (PTEs) from tofu consumption

Potentially toxic elements (PTEs) (V, B, Ba, Li, Sr, Cr, Ni, Al, Pb, Cd) were determined in 130 samples of different tofu types (natural, flavored, smoked, and fresh made) by ICP-OES (inductively coupled plasma optical emission spectrometry). Al was the most notable element found with the highest concentration (6.71 mg/kg ww) found in flavored tofu. Ni level (0.38 mg/kg) stands out in smoked tofu. European tofu has higher PTE levels than Chinese tofu. Organic-produced tofu has higher PTE concentrations than conventional produced tofu. A total of 200 g/day of smoked tofu confers a contribution percentage of 39.6% of its TDI (tolerable daily intake). In addition, 200 g/day of flavored tofu would mean a high Pb contribution with a 23.2% of the BMDL (benchmark dose level) set in 0.63 μg/kg bw/day to the development of nephrotoxicity. Mean consumption would not pose a risk to adults' health. Considering the obtained results, it would be advisable to establish limits for certain metals such as Pb, Al, and Ni in this type of product. Furthermore, it is recommendable to set consumer guidelines to some tofu types in order to avoid excessive intake of PTEs.

Standardized Recipes and Their Influence on the Environmental Impact Assessment of Mixed Dishes: A Case Study on Pizza

Food and diet life cycle assessment (LCA) studies offer insights on the environmental performance and improvement potential of food systems and dietary patterns. However, the influence of ingredient resolution in food-LCAs is often overlooked. To address this, four distinct decomposition methods were used to determine ingredients for mixed dishes and characterize their environmental impacts, using the carbon footprint of the U.S. daily pizza intake as a case study. Pizza-specific and daily pizza intake carbon footprints varied substantially between decomposition methods. The carbon footprint for vegetarian pizza was 0.18–0.45 kg CO2eq/serving, for meat pizza was 0.56–0.73 kg CO2eq/serving, and for currently consumed pizzas in the U.S. (26.3 g/person/day; 75 pizzas types) was 0.072–0.098 kg CO2eq/person/day. These ranges could be explained by differences in pizza coverage, ingredient resolution, availability of ingredient environmental information, and ingredient adjustability for losses between decomposition methods. From the approaches considered, the USDA National Nutrient Database for Standard Reference, which reports standardized food recipes in relative weights, appears to offer the most appropriate and useful food decompositions for food-LCAs. The influence and limitations of sources of reference flows should be better evaluated and acknowledged in food and diet LCAs.

Healthy diets can create environmental trade-offs, depending on how diet quality is measured

Background

There is an urgent need to assess the linkages between diet patterns and environmental sustainability in order to meet global targets for reducing premature mortality and improving sustainable management of natural resources. This study fills an important research gap by evaluating the relationship between incremental differences in diet quality and multiple environmental burdens, while also accounting for the separate contributions of retail losses, inedible portions, and consumer waste.

Methods

Cross sectional, nationally-representative data on food intake in the United States were acquired from the National Health and Nutrition Examination Survey (2005–2016), and were linked with nationally-representative data on food loss and waste from published literature. Survey-weighted procedures estimated daily per capita food retail loss, food waste, inedible portions, and consumed food, and were summed to represent Total Food Demand. Diet quality was measured using the Healthy Eating Index-2015 and the Alternative Healthy Eating Index-2010. Data on food intake, loss, and waste were inputted into the US Foodprint Model to estimate the amount of agricultural land, fertilizer nutrients, pesticides, and irrigation water used to produce food.

Results

This study included dietary data from 50,014 individuals aged ≥2 y. Higher diet quality (HEI-2015 and AHEI-2010) was associated with greater per capita Total Food Demand, as well as greater retail loss, inedible portions, consumer waste, and consumed food (P < 0.001 for all comparisons). Consumed food accounted for 56–74% of agricultural resource use (land, fertilizer nutrients, pesticides, and irrigation water), retail loss accounted for 4–6%, inedible portions accounted for 2–15%, and consumer waste accounted for 20–23%. Higher diet quality was associated with lower use of agricultural land, but the relationship to other agricultural resources was dependent on the tool used to measure diet quality (HEI-2015 vs. AHEI-2010).

Conclusions

Over one-quarter of the agricultural inputs used to produce Total Food Demand were attributable to edible food that was not consumed. Importantly, this study also demonstrates that the relationship between diet quality and environmental sustainability depends on how diet quality is measured. These findings have implications for the development of sustainable dietary guidelines, which requires balancing population-level nutritional needs with the environmental impacts of food choices.

Association between diet-related greenhouse gas emissions and nutrient intake adequacy among Japanese adults

OBJECTIVES

A growing number of Western studies have been exploring sustainable and healthy dietary patterns that target to reduce diet-related greenhouse gas emissions (GHGE) and to achieve nutritional needs. However, research is limited among Asian populations, where food sources for diet-related GHGE differ from those in Western populations. This study aimed to investigate associations between diet-related GHGE and the prevalence of inadequate nutritional intake.

METHODS

A cross-sectional study was carried out among 392 healthy Japanese volunteers aged 20-69 years. Dietary intake was assessed by four-non-consecutive day diet record. Diet-related GHGE was estimated using the Global Link Input-Output model and adjusted for energy intake by residual method. Prevalence of inadequacy was defined as a percentage of participants with nutrient intake outside the Tentative Dietary Goal for Preventing Lifestyle-Related Disease or below the Estimated Average Requirement defined by the Dietary Reference Intakes (DRIs) for Japanese. The association between diet-related GHGE and the prevalence of inadequacy of the usual intake of each nutrient was examined using logistic regression models.

RESULTS

Participants with higher diet-related GHGE had overall better adherence to the DRIs. Intakes of all selected nutrients were positively associated with diet-related GHGE, except for carbohydrate, total fat, and saturated fat. With increasing quartile of diet-related GHGE, the prevalence of inadequacy decreased for protein, dietary fiber, potassium, vitamins A, B-6, and C, thiamin, riboflavin, calcium, magnesium, iron, and zinc, while that for sodium increased.

CONCLUSIONS

Diets with lower diet-related GHGE did not have better adherence to the DRIs compared to diets with higher diet-related GHGE among Japanese adults. Drastic dietary change or other strategies such as improving the food system would be needed to achieve a sustainable and healthy diet among Japanese.

Meeting EAT-Lancet Food Consumption, Nutritional, and Environmental Health Standards: A U.S. Case Study across Racial and Ethnic Subgroups

In 2019, The EAT-Lancet Commission developed criteria to assist policymakers and health care systems worldwide in sustaining natural resources to feed a forecasted 10 billion people through the year 2050. Although American dietary habits and underlying food production practices have a disproportionately negative impact on land, greenhouse gas (GHG), and water resources, there is limited information on how this population can meet the EAT-Lancet criteria. To address this, we measured adherence to an adapted version of the EAT-Lancet diet score criteria in United States (U.S.) populations overall and across racial/ethnic subgroups (i.e., black, Latinx, and white). In addition, we assessed the benefits of adherence in terms of saved environmental resources (i.e., land, GHG, and water). By performing these objectives, we provide vital information for the development of effective intervention strategies in the U.S. with enough refinement to address the human health and environmental implications of marginalized populations. Our results demonstrate that, on average, Americans do not meet EAT-Lancet criteria overall or across racial/ethnic subgroups. Shifting dietary intakes to meet the criteria could reduce environmental degradation between 28% and 38%. Furthermore, these methods can be adapted to other nations for the development of meaningful strategies that address the food, energy, and water challenges of our time.

The Climate and Nutritional Impact of Beef in Different Dietary Patterns in Denmark

There is public focus on the environmental impact, and in particular, the emissions of greenhouse gases (GHG), related to our food consumption. The aim of the present study was to estimate the carbon footprint (CF), land use and nutritional impact of the different beef products ready to eat in different real-life dietary patterns. Beef products accounted for 513, 560, 409 and 1023 g CO₂eq per day, respectively, in the four dietary patterns (Traditional, Fast-food, Green, and High-beef). The total CFs of these diets were 4.4, 4.2, 4.3 and 5.0 kg CO₂eq per day (10 MJ)_, respectively. The Green diet had almost the same CF as the Traditional and the Fast-food diets despite having the lowest intake of beef as well as the lowest intake of red meat in total. A theoretical substitution of beef with other animal products or legumes in each of these three diets reduced the diets' CF by 4-12% and land use by 5-14%. As regards nutrients, both positive and negative impacts of these substitutions were found but only a few of particular nutritional importance, indicating that replacing beef with a combination of other foods without a significant effect on the nutrient profile of the diet is a potential mitigation option.

Ultra-Processed Foods and Food System Sustainability: What Are the Links?

Global food systems are no longer sustainable for health, the environment, animal biodiversity and wellbeing, culinary traditions, socioeconomics, or small farmers. The increasing massive consumption of animal foods has been identified as a major determinant of unsustainability. However, today, the consumption of ultra-processed foods (UPFs) is also questioned. The main objective of this review is therefore to check the validity of this new hypothesis. We first identified the main ingredients/additives present in UPFs and the agricultural practices involved in their provision to agro-industrials. Overall, UPF production is analysed regarding its impacts on the environment, biodiversity, animal wellbeing, and cultural and socio-economic dimensions. Our main conclusion is that UPFs are associated with intensive agriculture/livestock and threaten all dimensions of food system sustainability due to the combination of low-cost ingredients at purchase and increased consumption worldwide. However, low-animal-calorie UPFs do not produce the highest greenhouse gas emissions (GHGEs) compared to conventional meat and dairy products. In addition, only reducing energy dense UPF intake, without substitution, might substantially reduce GHGEs. Therefore, significant improvement in food system sustainability requires urgently encouraging limiting UPF consumption to the benefit of mildly processed foods, preferably seasonal, organic, and local products.

Life cycle environmental impacts of food away from home and mitigation strategies-a review

Food production and consumption are major drivers of global environmental change, endangering the safe operating space of many environmental areas. Globally, there has been a growing trend of dining out, termed food away from home (FAFH) here, but its environmental sustainability has received insufficient attention. In this review, we examine studies quantifying the life-cycle environmental impacts of FAFH and identify mitigation strategies across the food supply chain. Overall, previous life cycle assessment (LCA) studies focused on the composition of FAFH meals and pre-use life cycle stages, especially food production. Greenhouse gas (GHG) emissions of FAFH meals range from 0.134 kg CO₂ e/meal to 13.2 kg CO₂ e/meal for school canteen meals, and from 0.60 kg CO₂ e/meal to 9.6 kg CO₂ e/meal for other catering services. Meat ingredients are the dominant source in a variety of environmental impact categories, and the food production stage usually accounts for over half of the total GHG emissions in the FAFH life cycle. Supply side mitigation strategies include advancing farming practices, updating cold transportation technology, and improving building energy efficiency. Demand side mitigation focuses on dietary change towards meals with less meat ingredients, with nudging and sustainable menu-designing as the two primary groups of strategies. Areas of focus for LCA include improving modeling of building energy consumption related to food consumption, advancing uncertainty characterization of life cycle results, and capturing geographical variations in food production.

Research trends and hotspots related to global carbon footprint based on bibliometric analysis: 2007-2018

As an important indicator of greenhouse gas emissions, the carbon footprint (CF) has become increasingly important in recent years under the dual pressures of global warming and international commitments to mitigate its effects. This study collected 3698 papers related to CF from the Web of Science database as research samples (year 2007 to 2018). Based on CiteSpace, the knowledge base, popular topics, and research trends of CF are presented. The results show the following: (1) from 2007 to 2018, the number of articles on CF have steadily increased. (2) After spatial analysis of the literature, we found that among research institutions, the Chinese Academy of Sciences has the largest number of publications on the issue. When it comes to country, three important research forces can be identified: USA, China, and UK. (3) Research on the CF is interdisciplinary; in addition to the traditional fields of environmental, political, economics, and computing, CF research has received attention from the Physics, Materials, Chemistry, Mathematics, and animal sciences. (4) Through keyword clustering, currently popular topics in research can be roughly divided into four aspects: CF calculation methods, research scales, energy, and agriculture. (5) The CF research during the study period is divided into four stages according to the burst time and content of the burst keywords. According to the research status and trend, this paper puts forward the future research direction of carbon footprint.

Daily cost of consumer food wasted, inedible, and consumed in the United States, 2001-2016

BACKGROUND

Consumer food waste in the United States represents substantial amounts of wasted nutrients, as well as needless environmental impact from wasted agricultural inputs, energy use, and greenhouse gas emissions. Efforts to reduce food waste at the consumer level are urgently needed to address the most prominent nutrition and environmental sustainability issues we now face. Importantly, individuals report that saving money is a salient motivator for reducing food waste, yet contemporary evidence on the consumer cost of wasted food is lacking. The objectives of this study are to 1) estimate the daily per capita cost of food wasted, inedible, and consumed 2) at home and away from home, and 3) by food group.

METHODS

This study utilizes cross-sectional, nationally-representative data on food intake from the National Health and Nutrition Examination Survey (2001-2016), linked with nationally representative data on food waste from published literature, as well as data on food prices and food price inflation from multiple publicly-available sources. Survey-weighted procedures estimated daily per capita expenditure on food waste for 39,758 adults aged ≥20 y.

RESULTS

Total daily per capita food expenditure was $13.27, representing 27% wasted, 14% inedible, and 59% consumed. The greatest daily food waste expenditures were observed for meat and seafood purchased for consumption outside of the home ($0.94, 95% CI: $0.90-0.99), and fruits and vegetables purchased for consumption in the home ($0.68, $0.63-0.73).

CONCLUSIONS

The most cost-effective ways to reduce food waste at the consumer level are to focus waste reduction efforts on meat and seafood purchased for consumption outside of the home and fruits and vegetables purchased for consumption in the home. A number of strategies are available to help consumers reduce their food waste, which can increase their financial flexibility to purchase more healthy foods while simultaneously reducing environmental impact.

The role of dairy foods in lower greenhouse gas emission and higher diet quality dietary patterns

PURPOSE

There is conflicting advice about the inclusion of dairy foods in a lower greenhouse gas (GHG) emission dietary pattern. Our purpose was to assess the prevalence of dairy food intake among higher diet quality and lower GHG emission diets in Australia and within these diets assess the association between level of dairy food intake and adequate intake of a broad range of nutrients.

METHODS

Dietary intake data collected using a 24-h recall process were sourced from the most recent Australian Health Survey. Diet quality was assessed by level of compliance with the food group-based Australian Dietary Guidelines. A subgroup of 1732 adult (19 years and above) daily diets was identified having higher diet quality score and lower GHG emissions (HQLE). Intake of core dairy foods (milk, cheese, yoghurt) was assessed and nutrient profiling was undertaken for 42 macro- and micronutrients.

RESULTS

The HQLE subgroup had 37% higher diet quality score and 43% lower GHG emissions than the average Australian adult diet (P < 0.05). Intake of dairy foods was very common (90% of HQLE diets) and greatly exceeded the intake of non-dairy alternatives (1.53 serves compared to 0.04 serves). HQLE daily diets in the highest tertile of dairy food intake were more likely to achieve the recommended intake of a wide range of nutrients, including calcium, protein, riboflavin, vitamin B12, folate, phosphorous, magnesium, iodine and potassium compared to other HQLE daily diets.

CONCLUSION

Core dairy foods have an important role for achieving adequate nutrient intakes in a healthy and lower GHG emission dietary pattern in Australia.

Assessing the environmental impacts of halving food loss and waste along the food supply chain

Reducing food loss and waste (FLW) is widely recognized as an important lever for lowering the environmental impacts of food systems. The United Nations Sustainable Development Agenda includes a goal to reduce FLW by 50% by 2030. Given differences in resource inputs along the food supply chain (FSC), the environmental benefits of FLW reduction will vary by stage of the FSC. Here, we identify the points along the supply chain where a 50% FLW reduction could yield the largest potential environmental benefits, assuming that decreases in consumption propagate back up the supply chain to reduce production. We use an environmentally extended input-output (EEIO) model combined with data on rates of FLW to calculate the scale of the total environmental impacts of the U.S. food system resulting from lost or wasted food. We evaluate the maximum potential environmental benefit resulting from 50% FLW reduction at all possible combinations of six supply chain stages (agricultural production, food processing, distribution/retail, restaurant foodservice, institutional foodservice, and households). We find that FLW reduction efforts should target the foodservice (restaurant) sector, food processing sector, and household consumption. Halving FLW in the foodservice sector has the highest potential to reduce greenhouse gas output and energy use. Halving FLW in the food processing sector could reduce the most land use and eutrophication potential, and reducing household consumption waste could avert the most water consumption. In contrast, FLW reduction at the retail, institutional foodservice, and farm level averts less environmental impact. Our findings may help determine optimal investment in FLW reduction strategies.

Addressing the carbon footprint, healthfulness, and costs of self-selected diets in the USA: a population-based cross-sectional study

BACKGROUND

The role of diet in health is well established and, in the past decade, more attention has been given to the role of food choices in the environment. The agricultural sector produces about a quarter of the world's greenhouse gas emissions (GHGE), and meat production, especially beef, is an important contributor to global GHGE. Our study aimed to address a fundamental gap in the diet-climate literature: identifying consumers who are receptive to making dietary changes, and the effect of their potential changes on GHGE, diet healthfulness, and diet costs.

METHODS

Dietary data on US individuals from a nationally representative survey were linked to food-related GHGE. We identified individuals receptive to changing their diets (potential changers) as those who reported trying US dietary guidance and were likely to agree that humans contribute to climate change. We assessed GHGE, diet healthfulness measured by the Healthy Eating Index (HEI), and diet costs before and after hypothetical changes replacing either beef or meats with poultry or plant-protein foods.

FINDINGS

Our sample comprised 7188 individuals, of whom 16% were potential changers. These were disproportionately women, highly educated, or had higher income compared with individuals deemed not likely to change. Replacing 100% of beef intake in potential changers with poultry reduced mean dietary GHGE by 1·38 kg CO₂-equivalents per person per day (95% CI 1·19-1·58), a 35·7% decrease. This replacement also increased mean HEI by 1·7% and reduced mean diet costs by 1·7%. We observed the largest changes when replacing all beef, pork, or poultry intake with plant-protein foods (GHGE decreased by 49·6%, mean HEI increased by 8·7%, and dietary costs decreased by 10·5%). Hypothetical replacements in the potential changers alone resulted in whole population reductions in 1-day dietary GHGE of 1·2% to 6·7%, equivalent to 22-126 million fewer passenger vehicle km.

INTERPRETATION

Individual-level diet studies that include a variation in response by consumers can improve our understanding of the effects of climate policies such as those that include sustainability information in national dietary guidance. In our study, we found that changes by a small percentage of motivated individuals can modestly reduce the national dietary GHGE. Moreover, these substitutions can modestly improve diet healthfulness and reduce diet costs for individuals who make these changes.

FUNDING

Wellcome Trust.

The Environmental Foodprint of Obesity

Emissions of greenhouse gases (GHG) are linked to global warming and adverse climate changes. Meeting the needs of the increasing number of people on the planet presents a challenge for reducing total GHG burden. A further challenge may be the size of the average person on the planet and the increasing number of people with excess body weight. We used data on GHG emissions from various sources and estimated that obesity is associated with ~20% greater GHG emissions compared with the normal-weight state. On a global scale, obesity contributes to an extra GHG emissions of ~49 megatons per year of CO₂ equivalent (CO₂ eq) from oxidative metabolism due to greater metabolic demands, ~361 megatons per year of CO₂ eq from food production processes due to increased food intake, and ~290 megatons per year of CO₂ eq from automobile and air transportation due to greater body weight. Therefore, the total impact of obesity may be extra emissions of ~700 megatons per year of CO₂ eq, which is about 1.6% of worldwide GHG emissions. Inasmuch as obesity is an important contributor to global GHG burden, strategies to reduce its prevalence should prioritize efforts to reduce GHG emissions. Accordingly, reducing obesity may have considerable benefits for both public health and the environment.

An Environmental Impact Calculator for 24-h Diet Recalls

The production of food is associated with significant environmental impact. In this paper, we describe the first assessment of the environmental impact of food consumption in the United States using individually reported dietary intake data from a nationally representative sample. Using individual-level dietary intake data from the National Health and Nutrition Examination Survey (NHANES) and applying median environmental impact factors compiled by Poore and Nemecek (2018), we estimate that the daily diet that a non-institutionalized U.S. civilian reports results in a mean of 3.92 m2 (95% CI: 3.51–4.34) of land used, 2.26 kg (95% CI: 2.09–2.42)of CO2e emitted, and 159 L (95% CI: 150–168) of freshwater withdrawn. The scope of all impacts is agricultural; transportation, storage, and preparation were not included. These results suggest that the calculator is ready for further development. This calculator can be used to estimate the environmental impact of individual diets in the 5100 studies (as of November 2018) registered with the Automated Self-Administered 24-h Dietary Assessment Tool, in addition to the last two decades of the nationally representative NHANES research.

Comparing the Environmental Impacts of Meatless and Meat-Containing Meals in the United States

This study compares the environmental impacts of meatless and meat-containing meals in the United States according to consumption data in order to identify commercial opportunities to lower environmental impacts of meals. Average consumption of meal types (breakfast, lunch, dinner) were assessed using life cycle assessment. Retail and consumer wastes, and weight losses and gains through cooking, were used to adjust the consumption quantities to production quantities. On average, meatless meals had more than a 40% reduction in environmental impacts than meat-containing meals for any of the assessed indicators (carbon footprint, water use, resource consumption, health impacts of pollution, and ecosystem quality). At maximum and minimum for carbon footprint, meat-containing dinners were associated with 5 kgCO2e and meatless lunches 1 kg CO2e. Results indicate that, on average in the US, meatless meals lessen environmental impacts in comparison to meat-containing meals; however, animal products (i.e., dairy) in meatless meals also had a substantial impact. Findings suggest that industrial interventions focusing on low-impact meat substitutes for dinners and thereafter lunches, and low-impact dairy substitutes for breakfasts, offer large opportunities for improving the environmental performance of the average diet.

Achieving Healthy and Sustainable Diets: A Review of the Results of Recent Mathematical Optimization Studies

Climate protection and other environmental concerns render it critical that diets and agriculture systems become more sustainable. Mathematical optimization techniques can assist in identifying dietary patterns that both improve nutrition and reduce environmental impacts. Here we review 12 recent studies in which such optimization was used to achieve nutrition and environmental sustainability aims. These studies used data from China, India, and Tunisia, and from 7 high-income countries (France, Finland, Italy, the Netherlands, Sweden, the United Kingdom, and the United States). Most studies aimed to reduce greenhouse gas emissions (10 of 12) and half aimed also to reduce ≥1 other environmental impact, e.g., water use, fossil energy use, land use, marine eutrophication, atmospheric acidification, and nitrogen release. The main findings were that in all 12 studies, the diets optimized for sustainability and nutrition were more plant based with reductions in meat, particularly ruminant meats such as beef and lamb (albeit with 6 of 12 of studies involving increased fish in diets). The amount of dairy products also tended to decrease in most (7 of 12) of the studies with more optimized diets. Other foods that tended to be reduced included: sweet foods (biscuits, cakes, and desserts), savory snacks, white bread, and beverages (alcoholic and soda drinks). These findings were broadly compatible with the findings of 7 out of 8 recent review articles on the sustainability of diets. The literature suggests that healthy and sustainable diets may typically be cost neutral or cost saving, but this is still not clear overall. There remains scope for improvement in such areas as expanding research where there are no competing interests; improving sustainability metrics for food production and consumption; consideration of infectious disease risks from livestock agriculture and meat; and researching optimized diets in settings where major policy changes have occurred (e.g., Mexico's tax on unhealthy food).

A systems approach to assessing environmental and economic effects of food loss and waste interventions in the United States

Reducing food loss and waste (FLW) is critical for achieving healthy diets from sustainable food systems. Within the United States, 30% to 50% of food produced is lost or wasted. These losses occur throughout multiple stages of the food supply chain from production to consumption. Reducing FLW prevents the waste of land, water, energy, and other resources embedded in food and is therefore essential to improving the sustainability of food systems. Despite the increasing number of studies identifying FLW reduction as a societal imperative, we lack the information needed to assess fully the effectiveness of interventions along the supply chain. In this paper, we synthesize the available literature, data, and methods for estimating the volume of FLW and assessing the full environmental and economic effects of interventions to prevent or reduce FLW in the United States. We describe potential FLW interventions in detail, including policy changes, technological solutions, and changes in practices and behaviors at all stages of the food system from farms to consumers and approaches to conducting economic analyses of the effects of interventions. In summary, this paper comprehensively reviews available information on the causes and consequences of FLW in the United States and lays the groundwork for prioritizing FLW interventions to benefit the environment and stakeholders in the food system.

An energy- and nutrient-corrected functional unit to compare LCAs of diets

Dietary choices, a main driver of food production, play a significant role within the climate change arena. Consequently, there is a growing trend on publishing research assessing the environmental impacts of diets and dietary shifts, mainly following the life cycle assessment (LCA) methodology. However, several methodological issues still bring a challenge, especially in the definition of the function and the quantification of the functional unit (FU). The FU is the reference unit of an LCA study, and it is the basis for allowing comparison among different systems. This short communication defines the function of diets as the supply of the daily required amount of calories and nutrients, and it proposes a novel FU that accounts for the energy intake and the nutritional quality of the diet. In order to compare the performance of the proposed FU to the most commonly ones used for diet LCAs (mass-based and isocaloric), dietary scenarios within the Spanish context are assessed. On the one hand, using a mass-based FU, greenhouse gas (GHG) emissions are underestimated, since the nutrition properties of food are not considered, and, on the other hand, the isocaloric substitution does not allow comparison among diets with different levels of energy intake. In contrast, the proposed caloric- and nutrient-corrected FU allows to compare diets that differ in energy and nutritional quality in a fairer way. Finally, it is recommended to use this FU for future diet LCAs.

Environmental impacts of dietary shifts in India: A modelling study using nationally-representative data

Food production is a major driver of environmental change, and unhealthy diets are the leading cause of global disease burden. In high-income countries (HICs), modelling studies suggest that adoption of healthy diets could improve population health and reduce environmental footprints associated with food production. We assessed whether such benefits from dietary change could occur in India, where under-nutrition and overweight and obesity are simultaneously prevalent. We calculated the potential changes in greenhouse gas (GHG) emissions, blue and green water footprints (WFs), and land use (LU), that would result from shifting current national food consumption patterns in India to healthy diets (meeting dietary guidelines) and to "affluent diets" (those consumed by the wealthiest quartile of households, which may represent future purchasing power and nutritional trajectories). Dietary data were derived from the 2011-12 nationally-representative household expenditure survey, and we assessed dietary scenarios nationally and across six Indian sub-regions, by rural or urban location, and for those consuming above or below recommended dietary energy intakes. We modelled the changes in consumption of 34 food groups necessary to meet Indian dietary guidelines, as well as an affluent diet representative of those in the highest wealth quartile. These changes were combined with food-specific data on GHG emissions, calculated using the Cool Farm Tool, and WF and LU adapted from the Water Footprint Network and Food and Agriculture Organization, respectively. Shifting to healthy guidelines nationally required a minor increase in dietary energy (3%), with larger increases in fruit (18%) and vegetable (72%) intake, though baseline proportion of dietary energy from fat and protein was adequate and did not change significantly. Meeting healthy guidelines slightly increased environmental footprints by about 3-5% across GHG emissions, blue and green WFs, and LU. However, these national averages masked substantial variation within sub-populations. For example, shifting to healthy diets among those with dietary energy intake below recommended guidelines would result in increases of 28% in GHG emissions, 18 and 34% in blue and green WFs, respectively, and 41% in LU. Decreased environmental impacts were seen among those who currently consume above recommended dietary energy (-6 to -16% across footprints). Adoption of affluent diets by the whole population would result in increases of 19-36% across the environmental indicators. Specific food groups contributing to these shifts varied by scenario. Environmental impacts also varied markedly between six major Indian sub-regions. In India, where undernutrition is prevalent, widespread adoption of healthy diets may lead to small increases in the environmental footprints of the food system relative to the status quo, although much larger increases would occur if there was widespread adoption of diets currently consumed by the wealthiest quartile of the population. To achieve lower diet-related disease burdens and reduced environmental footprints of the food system, greater efficiency of food production and reductions in food waste are likely to be required alongside promotion of healthy diets.

Carbon footprint of self-selected US diets: nutritional, demographic, and behavioral correlates

BACKGROUND

A substantial portion of greenhouse gas emissions (GHGE) has been attributed to the food sector, but little is known about the association between the carbon footprint of individual self-selected diets in the United States and nutritional quality.

OBJECTIVES

The aims of this study were to assess the GHGE from individual self-selected diets in the United States and examine their association with nutritional quality of the diets, demographic patterns, and food-related behaviors.

METHODS

The dietary GHGE from US adults (>18 y, N = 16,800) in the 2005-2010 National Health and Nutrition Examination Survey (NHANES) were calculated by linking all foods consumed in their 24-h recall diets to our new database of food environmental impacts. Diets were ranked by GHGE/1000 kcal. Those in the top and bottom quintiles were compared on the US Healthy Eating Index (HEI) and on the amounts of specific nutrients known to be under- or overconsumed in the US population. Demographic and behavioral variables from the NHANES were also correlated to these dietary carbon footprints.

RESULTS

Diets in the bottom quintile accounted for one-fifth the total emissions (GHGE/1000 kcal) of those in the top quintile, yet had significantly higher (P < 0.001) HEI scores by 2.3 ± 0.7 points on a 100-point scale. These low-GHGE diets contained higher amounts of fiber and vitamin E and lower amounts of sodium and saturated fats, whereas high-GHGE diets contained higher amounts of vitamins A and D, choline, calcium, iron, and potassium. Low-GHGE diets had less meat, dairy, and solid fats, and more poultry, plant protein foods, oils, whole and refined grains, and added sugars.

CONCLUSIONS

Food patterns responsible for lower GHGE had a better overall diet quality and were more nutritious on several key dimensions, although not all. These results can inform dietary guidance and other policies that seek to address the goals of improved dietary intakes and reduced food-related emissions.

Potential Changes in Greenhouse Gas Emissions from Refrigerated Supply Chain Introduction in a Developing Food System

Refrigeration transforms developing food systems, changing the dynamics of production and consumption. This study models the introduction of an integrated refrigerated supply chain, or "cold chain," into sub-Saharan Africa and estimates changes in preretail greenhouse gas (GHG) emissions if the cold chain develops similarly to North America or Europe. Refrigeration presents an important and understudied trade-off: the ability to reduce food losses and their associated environmental impacts, but increasing energy use and creating GHG emissions. It is estimated that postharvest emissions added from cold chain operation are larger than food loss emissions avoided, by 10% in the North American scenario and 2% in the European scenario. The cold chain also enables changes in agricultural production and diets. Connected agricultural production changes decrease emissions, while dietary shifts facilitated by refrigeration may increase emissions. These system-wide changes brought about by the cold chain may increase the embodied emissions of food supplied to retail by 10% or decrease them by 15%, depending on the scenario.

Position of the Society for Nutrition Education and Behavior: The Importance of Including Environmental Sustainability in Dietary Guidance

It is the position of the Society for Nutrition Education and Behavior that environmental sustainability should be inherent in dietary guidance, whether working with individuals or groups about their dietary choices or in setting national dietary guidance. Improving the nutritional health of a population is a long-term goal that requires ensuring the long-term sustainability of the food system. Current environmental trends, including those related to climate change, biodiversity loss, land degradation, water shortages, and water pollution, threaten long-term food security and are caused in part by current diets and agricultural practices. Addressing these problems while producing more food for a growing population will require changes to current food systems. Dietary choices have a significant role in contributing to environmental impacts, which could be lessened by consuming fewer overconsumed animal products and more plant-based foods while reducing excess energy intake and the amount of food wasted. Discussion of sustainability within governmental dietary guidance is common in many countries, is consistent with previous US guidelines, and is within the scope of authorizing legislation. Dietary choices are a personal matter, but many American consumers are motivated by a concern for the environment and would welcome sound advice from credentialed nutrition professionals. More opportunities are needed for developing such interdisciplinary knowledge among nutritionists.

Trends in types of protein in US adults: results from the National Health and Nutrition Examination Survey 1999-2010

OBJECTIVE

To delineate trends in types of protein in US adults from 1999 to 2010, we examined the mean intake of beef, pork, lamb or goat, chicken, turkey, fish, dairy, eggs, legumes, and nuts and seeds (grams per kilogram of body weight) among adults and according to subgroups, including chronic disease status.

DESIGN

Six cycles of the repeated cross-sectional surveys.

SETTING

National Health and Nutrition Examination Survey 1999 to 2010.

PARTICIPANTS

US adults aged ≥20 years (n 29 145, range: 4252-5762 per cycle).

RESULTS

Overall, mean chicken (0·47 to 0·52 g/kg), turkey (0·09 to 0·13 g/kg), fish (0·21 to 0·27 g/kg) and legume (0·21 to 0·26 g/kg) intake increased, whereas dairy decreased (3·56 to 3·22 g/kg) in US adults (P <0·03). Beef, lamb or goat intake did not change in adults or among those with a chronic disease. Over time, beef intake declined less, and lamb or goat intake increased more, for those of lower socio-economic status compared with those of higher socio-economic status.

CONCLUSIONS

Despite recommendations to reduce red meat, beef, lamb or goat intake did not change in adults, among those with a chronic disease or with lower socio-economic status.