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

Switches in food and beverage product purchases can reduce greenhouse gas emissions in Australia

Switching between similar food and beverage products may reduce greenhouse gas emissions (GHGe). Here, using consumer data linked to 23,550 product-specific GHGe values, we estimated annual GHGe attributable to product purchases consumed at home in Australia and calculated reductions from specific switches. Potential changes to mean Health Star Rating, mean energy density and the proportion of ultraprocessed foods purchased were assessed. Approximately 31 million tonnes of GHGe were attributable to products consumed at home in 2019, the three highest contributors of GHGe being 'meat and meat products' (49%), 'dairy' (17%) and 'non-alcoholic beverages' (16%). Switching higher-emission products for 'very similar' lower-emission products could reduce total emissions by 26%. Switches to 'less similar' lower-emission products could lead to a 71% reduction. Switches had little impact on the average Health Star Rating, energy density of purchases and proportion of ultraprocessed foods purchased. Directing manufacturing and marketing towards lower-environmental-impact products and signposting such options to consumers are key.

Effects of red meat taxes and warning labels on food groups selected in a randomized controlled trial

BACKGROUND

High consumption of red and processed meat contributes to both health and environmental harms. Warning labels and taxes for red meat reduce selection of red meat overall, but little is known about how these potential policies affect purchases of subcategories of red meat (e.g., processed versus unprocessed) or of non-red-meat foods (e.g., cheese, pulses) relevant to health and environmental outcomes. This study examined consumer responses to warning labels and taxes for red meat in a randomized controlled trial.

METHODS

In October 2021, we recruited 3,518 US adults to complete a shopping task in a naturalistic online grocery store. Participants were randomly assigned to one of four arms: control (no warning labels or tax), warning labels only (health and environmental warning labels appeared next to products containing red meat), tax only (prices of products containing red meat were increased 30%) or combined warning labels + tax. Participants selected items to hypothetically purchase, which we categorized into food groups based on the presence of animal- and plant-source ingredients (e.g., beef, eggs, pulses), meat processing level (e.g., processed pork versus unprocessed pork), and meat species (e.g., beef versus pork). We assessed the effects of the warning labels and tax on selections from each food group.

RESULTS

Compared to control, all three interventions led participants to select fewer items with processed meat (driven by reductions in processed pork) and (for the tax and warning labels + tax interventions only) fewer items with unprocessed meat (driven by reductions in unprocessed beef). All three interventions also led participants to select more items containing cheese, while only the combined warning labels + tax intervention led participants to select more items containing processed poultry. Except for an increase in selection of pulses in the tax arm, the interventions did not affect selections of fish or seafood (processed or unprocessed), eggs, or plant-based items (pulses, nuts & seeds, tofu, meat mimics, grains & potatoes, vegetables).

CONCLUSIONS

Policies to reduce red meat consumption are also likely to affect consumption of other types of foods that are relevant to both health and environmental outcomes.

TRIAL REGISTRATION

NCT04716010 on www.

CLINICALTRIALS

gov .

Development of a sustainable diet index in US adults

BACKGROUND

A transformation towards healthy diets through a sustainable food system is essential to enhance both human and planet health. Development of a valid, multidimensional, quantitative index of a sustainable diet would allow monitoring progress in the US population. We evaluated the content and construct validity of a sustainable diet index for US adults (SDI-US) based on data collected at the individual level.

METHODS

The SDI-US, adapted from the SDI validated in the French population, was developed using data on US adults aged 20 years and older from the National Health and Nutrition Examination Survey, 2007-2018 (n = 25,543). The index consisted of 4 sub-indices, made up of 12 indicators, corresponding to 4 dimensions of sustainable diets (nutritional quality, environmental impacts, affordability (economic), and ready-made product use behaviors (sociocultural)). A higher SDI-US score indicates greater alignment with sustainable diets (range: 4-20). Validation analyses were performed, including the assessment of the relevance of each indicator, correlations between individual indicators, sub-indices, and total SDI-US, differences in scores between sociodemographic subgroups, and associations with selected food groups in dietary guidelines, the alternative Mediterranean diet (aMed) score, and the EAT-Lancet diet score.

RESULTS

Total SDI-US mean was 13.1 (standard error 0.04). The correlation between SDI-US and sub-indices ranged from 0.39 for the environmental sub-index to 0.61 for the economic sub-index (Pearson Correlation coefficient). The correlation between a modified SDI-US after removing each sub-index and the SDI-US ranged from 0.83 to 0.93. aMed scores and EAT-Lancet diet scores were significantly higher among adults in the highest SDI-US quintile compared to the lowest quintile (aMed: 4.6 vs. 3.2; EAT-Lancet diet score: 9.9 vs. 8.7 p < .0001 for both).

CONCLUSIONS

Overall, content and construct validity of the SDI-US were acceptable. The SDI-US reflected the key features of sustainable diets by integrating four sub-indices, comparable to the SDI-France. The SDI-US can be used to assess alignment with sustainable diets in the US. Continued monitoring of US adults' diets using the SDI-US could help improve dietary sustainability.

Dietary quality and dietary greenhouse gas emissions in the USA: a comparison of the planetary health diet index, healthy eating index-2015, and dietary approaches to stop hypertension

BACKGROUND

The Planetary Health Diet Index (PHDI) measures adherence to the dietary pattern presented by the EAT-Lancet Commission, which aligns health and sustainability targets. There is a need to understand how PHDI scores correlate with dietary greenhouse gas emissions (GHGE) and how this differs from the carbon footprints of scores on established dietary recommendations. The objectives of this study were to compare how the PHDI, Healthy Eating Index-2015 (HEI-2015) and Dietary Approaches to Stop Hypertension (DASH) relate to (a) dietary GHGE and (b) to examine the influence of PHDI food components on dietary GHGE.

METHODS

We used life cycle assessment data from the Database of Food Recall Impacts on the Environment for Nutrition and Dietary Studies to calculate the mean dietary GHGE of 8,128 adult participants in the 2015-2016 and 2017-2018 cycles of the National Health and Nutrition Examination Survey (NHANES). Poisson regression was used to estimate the association of (a) quintiles of diet score and (b) standardized dietary index Z-scores with dietary GHGE for PHDI, HEI-2015, and DASH scores. In secondary analyses, we used Poisson regression to assess the influence of individual PHDI component scores on dietary GHGE.

RESULTS

We found that higher dietary quality on all three indices was correlated with lower dietary GHGE. The magnitude of the dietary quality-dietary GHGE relationship was larger for PHDI [-0.4, 95% CI (-0.5, -0.3) kg CO2 equivalents per one standard deviation change] and for DASH [-0.5, (-0.4, -0.6) kg CO2-equivalents] than for HEI-2015 [-0.2, (-0.2, -0.3) kg CO2-equivalents]. When examining PHDI component scores, we found that diet-related GHGE were driven largely by red and processed meat intake.

CONCLUSIONS

Improved dietary quality has the potential to lower the emissions impacts of US diets. Future efforts to promote healthy, sustainable diets could apply the recommendations of the established DASH guidelines as well as the new guidance provided by the PHDI to increase their environmental benefits.

Aging Increases Global Annual Food Greenhouse Gas Emissions up to 300 Million Tonnes by 2100

The dietary preferences of the elderly population exhibit distinct variations from the overall averages in most countries, gaining increasing significance due to aging demographics worldwide. These dietary preferences play a crucial role in shaping global food systems, which will result in changed environmental impacts in the future such as greenhouse gas (GHG) emissions. We present a quantitative evaluation of the influence of population aging on the changes in GHG emissions from global food systems. To achieve this, we developed regional dietary coefficients (DCs) of the elderly based on the Global Dietary Database (GDD). We then reconciled the GDD with the dataset from the Food and Agriculture Organization of the United Nations (FAO) to calculate the food GHG emissions of the average population in each of the countries. By applying the DCs, we estimated the national food GHG emissions and obtained the variations between the emissions from aged and average populations. We employed a modified version of the regional integrated model of climate and the economy model (RICE) to forecast the emission trends in different countries based on FAO and GDD data. This integrated approach allowed us to evaluate the dynamic relationships among aging demographics, food consumption patterns, and economic developments within regions. Our results indicate that the annual aging-embodied global food GHG emissions will reach 288 million tonnes of CO2 equivalent (Mt CO2e) by 2100. This estimation is crucial for policymakers, entrepreneurs, and researchers as it provides insights into a potential future environmental challenge and emphasizes the importance of sustainable food production and consumption strategies to GHG emission mitigations associated with aging dietary patterns.

Opportunities for Consistent and Holistic Metrics to Support Food Systems Transformation: A Summary of a Symposium Presented at Nutrition 2023

There is an urgent need for global food systems transformation to realize a future where planetary health reaches its full potential. Paramount to this vision is the ability of stakeholders across sectors to understand how foods and dietary patterns impact food systems inclusive of all domains of sustainability-environmental, nutrition/health, economic and social. This article is a synopsis of presentations by 3 food systems experts to share the latest science in a session entitled "How do you measure sustainability? Opportunities for consistent and holistic metrics to support food systems transformation" at the American Society for Nutrition's 2023 annual conference. As summarized here, global population data showing widespread malnutrition underscore the important role of dietary diversity through a balance of plant- and animal-source foods to achieve nutritionally adequate diets and reduce risk of noncommunicable diseases. Yet, recent international audits of countries, companies, and organizations and their sustainability targets largely demonstrate an underrepresentation of robust nutrition/health metrics to support public nutrition and health progress. Addressing limitations in diet-sustainability modeling systems provides a viable opportunity to accurately reflect the important contributions and trade-offs of diets across all domains of sustainability to ultimately support evidence-based decision making in advancing healthy food systems.

Adherence to the Mediterranean Food Pattern and Carbon Footprint of Food Intake by Employees of a University Setting in Portugal

BACKGROUND

The Mediterranean diet is characterized by the predominance of the consumption of fruit, vegetables, cereals, nuts, and pulses; consumption of olive oil as the main source of fat; regular but moderate consumption of win; moderate consumption of fish, dairy products, eggs, and white meats; and low consumption of red meat as well as sugar and sugary products. In addition to the reported health benefits, the Mediterranean diet has also been widely recognized as a sustainable food pattern. The objective of this study was to understand the relationship between the degree of adherence to the Mediterranean diet of employees of the University of Porto and the relationship with the carbon footprint of their food consumption.

METHODS

An observational, analytical study was carried out, through the analysis of food consumption data collected in the form of a survey in the previous 24 h inserted in the eAT24 software, as well as the analysis of sociodemographic, lifestyle, and health data collected in the questionnaire. The carbon footprint was calculated from the previous 24 h surveys using data available on a website, obtained in carbon dioxide equivalent per kilogram of food. Sociodemographic, eating habit, and lifestyle questions were selected to understand the relationship between these and adherence to the Mediterranean diet and the carbon footprint of food consumption.

RESULTS

In total, 13.2% of the participants had a Mediterranean diet score equal to or greater than six, and the sample had an average food intake carbon footprint of 8146 ± 3081 CO2eq/Kg of food. A weak, statistically significant positive correlation (r = 0.142, p = 0.006) was observed between Mediterranean diet adherence and the carbon footprint of food intake.

CONCLUSIONS

Most of the participants had a low adherence to the Mediterranean diet, as well as a high carbon footprint of food intake when compared to other countries. People with higher scores for Mediterranean diet adherence have, on average, a higher carbon footprint from food consumption intake.

Adherence to the Planetary Health Diet Index and correlation with nutrients of public health concern: an analysis of NHANES 2003-2018

BACKGROUND

The Planetary Health Diet Index (PHDI) is a novel measure adapted to quantify alignment with the dietary evidence presented by the EAT-Lancet Commission on Food, Planet, Health.

OBJECTIVES

To examine how population-level health and sustainability of diet as measured by the PHDI changed from 2003 to 2018, and to assess how PHDI correlated with inadequacy for nutrients of public health concern (iron, calcium, potassium, and fiber) in the United States.

METHODS

We estimated survey-weighted trends in PHDI scores and median intake of PHDI components in a nationally representative sample of 33,859 adults aged 20+ y from 8 cycles (2003-2018) of the National Health and Nutrition Examination Survey with 2 d of dietary recall data. We used the National Cancer Institute method to examine how PHDI correlated with inadequate intake of iron, calcium, potassium, and fiber.

RESULTS

Out of a theoretical range of 0-140, the median PHDI value increased by 4.2 points over the study period, from 62.7 (95% confidence interval [CI]: 62.0, 63.4) points in 2003-2004 to 66.9 (66.2, 67.7) points in 2017-2018 (P-trend < 0.001), although most of this change occurred before 2011-2012 and plateaued thereafter. For adequacy components that are encouraged for consumption, nonstarchy vegetable intake significantly decreased over time, whereas whole grains, nuts and seeds, and unsaturated oils increased. For moderation components with recommended limits for consumption, poultry and egg intake increased, but red and processed meat, added sugars, saturated fats, and starchy vegetables decreased over time. Higher PHDI values were associated with a lower probability of iron, fiber, and potassium inadequacy.

CONCLUSIONS

Although there have been positive changes over the past 20 y, there is substantial room for improving the health and sustainability of the United States diet. Shifting diets toward EAT-Lancet recommendations would improve nutrient adequacy for iron, fiber, and potassium. Policy action is needed to support healthier, more sustainable diets in the United States and globally.

Partial substitutions of animal with plant protein foods in Canadian diets have synergies and trade-offs among nutrition, health and climate outcomes

Dietary guidelines emphasize the consumption of plant protein foods, but the implications of replacing animal with plant sources on a combination of diet sustainability dimensions are unknown. Using a combination of data from a national nutrition survey, greenhouse gas emissions from dataFIELD and relative risks from the Global Burden of Disease Study 2017, we assess the impact of partially substituting red and processed meat or dairy with plant protein foods in Canadian self-selected diets on nutrition, health and climate outcomes. The substitutions induced minor changes to the percentage of the population below requirements for nutrients of concern, but increased calcium inadequacy by up to 14% when dairy was replaced. Replacing red and processed meat or dairy increased life expectancy by up to 8.7 months or 7.6 months, respectively. Diet-related greenhouse gas emissions decreased by up to 25% for red and processed meat and by up to 5% for dairy replacements. Co-benefits of partially substituting red and processed meat with plant protein foods among nutrition, health and climate outcomes are relevant for reshaping consumer food choices in addressing human and planetary health.

The association between food environment, diet quality and malnutrition in low- and middle-income adult populations across the rural-Urban gradient in Vietnam

BACKGROUND

Economic reforms and trade liberalisation in Vietnam have transformed the food environment, influencing dietary patterns and malnutrition status. The present study focuses on the relationship between food environments (proximity and density of food outlets) and malnutrition (underweight, overweight, obesity) through diet quality in adult populations across urban, periurban and rural areas of Vietnam.

METHODS

We evaluated food environment by geospatial mapping of food outlets through a transect walk across the "food ecosystem" from rural to urban areas. Diet quality was assessed using the Diet Quality Index - Vietnamese (DQI-V) comprising Variety, Adequacy, Moderation and Balance components. Malnutrition status was determined using body mass index. We performed a mediation analysis utilising mixed effect models to control for neighbourhood clustering effects. Confounders included age, education, income and nutrition knowledge score.

RESULTS

Analysis of data from 595 adult participants (mean ± SD age: 31.2 ± 6.4 years; 50% female) found that longer distance to the nearest food outlet was associated with higher overall DQI-V (β = 2.0; 95% confidence interval = 0.2-3.8; p = 0.036) and the Moderation component (β = 2.6; 95% confidence interval = 1.2-4.0; p = 0.001). Outlet density shows a negative association with the odds of underweight among women (odds ratio = 0.62; 95% confidence interval = 0.37-0.96). However, we did not observe statistically significant relationships between diet quality and malnutrition. Education and nutrition knowledge scores were positively associated with diet diversity, while income was negatively associated with diet moderation.

CONCLUSIONS

The findings of the present study have important implications for nutrition and dietetics practice in Vietnam and globally. It emphasises the need to consider various dimensions of sustainable diets, including economic, health and socio-cultural/political factors. Longer distances to food outlets are associated with higher diet quality, whereas lower food outlet density increases the odds of underweight among women. This poses challenges in balancing modernisation and its adverse effects on sustainable food systems. Socio-economic status consistently correlated with diet quality and malnutrition, necessitating further research to promote healthy diets across socio-economic strata.

What is the climate footprint of therapeutic diets for people with chronic kidney disease? Results from an Australian analysis

BACKGROUND

Immediate action is needed to stabilise the climate. Dietitians require knowledge of how the therapeutic diets they prescribe may contribute to climate change. No previous research has quantified the climate footprint of therapeutic diets. This study sought to quantify and compare the climate footprint of two types of therapeutic diets for people with chronic kidney disease (CKD) with two reference diets.

METHODS

A usual diet for an individual with CKD and a novel plant-based diet for CKD were compared with the current Australian diet and the Australian-adapted EAT Lancet Planetary Health Diet (PHD). The climate footprint of these diets was measured using the Global Warming Potential (GWP*) metric for a reference 71-year-old male.

RESULTS

No diets analysed were climate neutral, and therefore, all contribute to climate change. The novel plant-based diet for CKD (1.20 kg carbon dioxide equivalents [CO2 e] per day) produced 35% less CO2 e than the usual renal diet for an individual with CKD (1.83 kg CO2 e per day) and 50% less than the current Australian diet (2.38 kg CO2 e per day). The Australian-adapted EAT Lancet PHD (1.04 kg CO2 e per day) produced the least amount of CO2 e and 56% less than the current Australian diet. The largest contributors to the climate footprint of all four diets were foods from the meats and alternatives, dairy and alternatives and discretionary food groups.

CONCLUSIONS

Dietetic advice to reduce the climate footprint of therapeutic diets for CKD should focus on discretionary foods and some animal-based products. Future research is needed on other therapeutic diets.

Visualizing Data Interoperability for Food Systems Sustainability Research-From Spider Webs to Neural Networks

Food systems represent all elements and activities needed to feed the growing global population. Research on sustainable food systems is transdisciplinary, relying on the interconnected domains of health, nutrition, economics, society, and environment. The current lack of interoperability across databases poses a challenge to advancing research on food systems transformation. Crosswalks among largely siloed data on climate change, soils, agricultural practices, nutrient composition of foods, food processing, prices, dietary intakes, and population health are not fully developed. Starting with US Department of Agriculture FoodData Central, we assessed the interoperability of databases from multiple disciplines by identifying existing crosswalks and corresponding visualizations. Our visual demonstration serves as proof of concept, identifying databases in need of expansion, integration, and harmonization for use by researchers, policymakers, and the private sector. Interoperability is the key: ontologies and well-defined crosswalks are necessary to connect siloed data, transcend organizational barriers, and draw pathways from agriculture to nutrition and health.

Simple dietary substitutions can reduce carbon footprints and improve dietary quality across diverse segments of the US population

Changing what foods we eat could reduce environmental harms and improve human health, but sweeping dietary change is challenging. We used dietary intake data from a nationally representative sample of 7,753 US children and adults to identify simple, actionable dietary substitutions from higher- to lower-carbon foods (for example, substituting chicken for beef in mixed dishes such as burritos, but making no other changes to the diet). We simulated the potential impact of these substitutions on dietary carbon emissions and dietary quality. If all consumers who ate the high-carbon foods instead consumed a lower-carbon substitute, the total dietary carbon footprint in the United States would be reduced by more than 35%. Moreover, if adopted, these substitutions would improve consumers' overall dietary quality by 4-10%, with benefits projected for all age, gender, and racial and ethnic groups. These results suggest that a 'small changes' approach could be a valuable starting point for addressing diet's impact on climate and health.

Demographic and Socioeconomic Correlates of Disproportionate Beef Consumption among US Adults in an Age of Global Warming

Concern for the environment when making dietary choices has grown as the contribution of the food sector to global greenhouse gas emissions becomes more widely known. Understanding the correlates of beef eating could assist in the targeting of campaigns to reduce the consumption of high-impact foods. The objective of this study was to identify the demographic, socioeconomic, and behavioral correlates of disproportionate beef consumption in the United States. We analyzed 24-h dietary recall data from adults (n = 10,248) in the 2015-2018 National Health and Nutrition Examination Survey (NHANES). Disproportionate beef consumption was defined as an intake greater than four ounce-equivalents per 2200 kcal. Associations of this indicator variable with gender, age, race/ethnicity, education, family income, diet knowledge, and away-from-home meals were assessed using logistic regression, incorporating survey design and weighting. Disproportionate beef diets were consumed by 12% of individuals, but accounted for half of all beef consumed. Males were more likely than females (p < 0.001) to consume these diets. This relationship was seen in all bivariate and multivariable models. Older adults, college graduates, and those who looked up the MyPlate educational campaign online were less likely (p < 0.01) to consume a disproportionate beef diet. While almost one-third of reported consumption came from cuts of beef (e.g., steak or brisket), six of the top ten beef sources were mixed dishes: burgers, meat mixed dishes, burritos and tacos, frankfurters, soups, and pasta. Efforts to address climate change through diet modification could benefit from targeting campaigns to the highest consumers of beef, as their consumption accounts for half of all beef consumed.

Greater adherence to the Dietary Guidelines for Americans is associated with lower diet-related greenhouse gas emissions but higher costs

Introduction

Few studies have evaluated the sustainability of popular diet patterns in the US, which limits policy action and impedes consumer efficacy to make sustainable dietary changes. This study filled this gap by evaluating the relationship between diet quality, greenhouse gas emissions (GHGE), and diet cost for plant-based, restricted carbohydrate, low grain, low fat, and time restricted diet patterns.

Methods

Dietary data were retrieved from the National Health and Nutrition Examination Survey (2011-2018, n = 8,146) and linked with data on GHGE and food prices from publicly available databases. Diet quality was measured using the Healthy Eating Index-2015. The present study (1) compared the mean diet quality, GHGE, and diet cost between diet patterns, (2) evaluated the association of diet quality to GHGE and diet cost for each diet pattern, and (3) estimated the contribution of food sources to GHGE and diet cost for each diet pattern.

Results

Higher diet quality was associated with lower GHGE for the general population and for most diet patterns (p < 0.01) except for the plant-based and time restricted diet patterns (p > 0.05). Higher diet quality was associated with higher cost for the general population and for all dietary patterns (p < 0.01) except the time restricted diet pattern (p > 0.05). Protein foods, mostly beef, accounted for the largest share of GHGE (29-40%) and diet cost (28-47%) for all diet patterns except plant-based.

Discussion

Higher diet quality was associated with lower GHGE but was often accompanied by higher diet cost. These sustainability trade-offs can help inform major policy discussions in the US and shed light on further research needs in the area of food systems transformation.

Greenhouse gas emissions, cost, and diet quality of specific diet patterns in the United States

BACKGROUND

Major policy agendas are calling for accelerated investment in research that addresses the impact of diet patterns on multiple domains of sustainability.

OBJECTIVE

To evaluate the comparative greenhouse gas emissions, diet cost, and diet quality of plant-based, low grain, restricted carbohydrate, low fat, and time restricted diet patterns on a daily per capita basis.

DESIGN

Dietary data from the National Health and Nutrition Examination Survey (2013-2016, n=4,025) were merged with data on greenhouse gas emissions (GHGE) and food prices from multiple databases. The Healthy Eating Index-2015 was used to measure diet quality.

RESULTS

The plant-based diet pattern had the lowest GHGE (3.5 kg CO2eq, 95% CI: 3.3, 3.8 kg CO2eq) and among the lowest diet cost ($11.51, 95% CI: $10.67, $12.41), but diet quality (45.8, 95% CI: 43.3, 48.5) was similar (P>0.005) to most other diet patterns. All of the sustainability impacts of the low grain diet pattern were intermediate. The restricted carbohydrate diet pattern had the highest diet cost ($18.46, 95% CI: $17.80, $19.13) but intermediate diet quality (46.8, 95% CI: 45.7, 47.9) and moderate-to-high GHGE (5.7 kg CO2eq, 95% CI: 5.4, 5.9 kg CO2eq). The low fat diet pattern had the highest diet quality (52.0, 95% CI: 50.8, 53.1) and intermediate GHGE (4.4 kg CO2eq, 95% CI: 4.1, 4.6 kg CO2eq) and diet cost ($14.53, 95% CI: $13.73, $15.38). The time restricted diet pattern had among the lowest diet quality score (42.6, 95% CI: 40.8, 44.6), had GHGE similar to most other diet patterns (4.6 kg CO2eq, 95% CI: 4.2, 5.0 kg CO2eq), and low-to-moderate diet cost ($12.34, 95% CI: $11.38, $13.40).

CONCLUSIONS

Most diet patterns were associated with sustainability trade-offs. The nature of those trade-offs can help inform discussions on food and nutrition policy in the US, including the National Strategy on Hunger, Nutrition, and Health, and future Dietary Guidelines for Americans.

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.

Modeling a localized metropolitan food system in the Midwest USA: Life cycle impacts of scenarios for Des Moines, Iowa

Food systems are energy-intensive, causing ≈25 % of anthropogenic global warming potential (GWP) and contributing to challenges across the food-energy-water nexus. The state of Iowa, USA, is of particular interest as a rainfed agricultural region of the upper Midwest; despite its highly productive landscape, a large proportion of food consumed by Iowa residents is imported. This study focused on the Des Moines Metropolitan Statistical Area (DM-MSA), a six-county area in central Iowa with a 2020 population of ≈700,000. A life cycle assessment approach was used to quantify environmental impacts (GWP, fossil energy and water consumption, land use); scenarios modeled provision and consumption of 50 % of nutritional requirements for the current DM-MSA population by food group (e.g., grains, proteins, vegetables). The four DM-MSA food system scenarios were: 1) current conditions (baseline), 2) local production for 50 % of food, 3) consumption changed to follow USA dietary guidelines, and 4) combined changes to production and consumption. Localizing food production reduced all environmental impacts more than following USA dietary guidelines. Compared to the baseline, 50 % local production scenarios reduced GWP and energy consumption (18-24 %) and water use (35-41 %) annually. Decreases by food group were least for protein (-10 % GWP) and greatest for fruits and vegetables (-58-62 % GWP). Local scenario alternatives could further reduce some environmental impacts if paired with a nutritionally- and environmentally-optimized diet (EAT-Lancet) providing the greatest change (-30-38 % for GWP and energy use) compared to the local scenario. A 50 % local production scenario for the DM-MSA could decrease GWP by 102 million CO_2eq yr^-1 and water use by 44 billion L yr^-1. However, this would require dietary changes based on seasonal food availability. Further development and co-simulation with other metropolitan-scale biophysical and social models will enhance understanding of food system drivers and support effective decision-making for urban food system improvements in the Midwest.

Five U.S. Dietary Patterns and Their Relationship to Land Use, Water Use, and Greenhouse Gas Emissions: Implications for Future Food Security

The U.S. agri-food system is a driver of climate change and other impacts. In order to achieve environmental targets that limit global mean temperature rise ≤2 °C, a shift in American dietary patterns is critical. The purpose of this study was twofold: (1) to determine the environmental impact (i.e., land use, water use, and GHG emissions) related to consumption of five U.S. dietary patterns (i.e., Current U.S., the Healthy U.S., Mediterranean, Healthy Vegetarian, and Vegan), and (2) to determine the specific impact of each food group in each dietary pattern on the three environmental indicators. This study utilized existing datasets to synthesize information related to the study's environmental indicators and food production and connected these data to the current U.S. diet and the USDA-defined diets. Results indicate that the three omnivore diets contributed the greatest to GHG emissions, land use and water use. The Vegan diet scored the lowest across all indicators, although the water required for plant-based protein nearly offset other water gains. For the omnivore diets, red meat and dairy milk contributed the most to each environmental indicator. By considering sustainability as well as health outcomes in their recommendations in the Dietary Guidelines, the USDA can have a critical role in shifting diets necessary to alter climate change trends.

Effect of Climate Change Impact Menu Labels on Fast Food Ordering Choices Among US Adults: A Randomized Clinical Trial

IMPORTANCE

There is increasing interest in strategies to encourage more environmentally sustainable food choices in US restaurants through the use of menu labels that indicate an item's potential impact on the world's climate. Data are lacking on the ideal design of such labels to effectively encourage sustainable choices.

OBJECTIVE

To test the effects of positive and negative climate impact menu labels on the environmental sustainability and healthfulness of food choices compared with a control label.

DESIGN, SETTING, AND PARTICIPANTS

This randomized clinical trial used an online national US survey conducted March 30 to April 13, 2022, among a nationally representative sample of adults (aged ≥18 years) from the AmeriSpeak panel. Data were analyzed in June to October 2022.

INTERVENTIONS

Participants were shown a fast food menu and prompted to select 1 item they would like to order for dinner. Participants were randomized to view menus with 1 of 3 label conditions: a quick response code label on all items (control group); green low-climate impact label on chicken, fish, or vegetarian items (positive framing); or red high-climate impact label on red meat items (negative framing).

MAIN OUTCOMES AND MEASURES

The main outcome was an indicator of selecting a sustainable item (ie, one without red meat). Secondary outcomes included participant health perceptions of the selected item and the Nutrition Profile Index (NPI) score of healthfulness.

RESULTS

Among 5049 participants (2444 female [51.6%]; 789 aged 18-29 years [20.3%], 1532 aged 30-44 years [25.9%], 1089 aged 45-59 years [23.5%], and 1639 aged ≥60 years [30.4%]; 142 Asian [5.3%], 611 Black [12.1%], and 3197 White [63.3%]; 866 Hispanic [17.2%]), high- and low-climate impact labels were effective at encouraging sustainable selections from the menu. Compared with participants in the control group, 23.5% more participants (95% CI, 13.7%-34.0%; P < .001) selected a sustainable menu item when menus displayed high-climate impact labels and 9.9% more participants (95% CI, 1.0%-19.8%; P = .03) selected a sustainable menu item when menus displayed low-climate impact labels. Across experimental conditions, participants who selected a sustainable item rated their order as healthier than those who selected an unsustainable item, according to mean perceived healthfulness score (control label: 3.4 points; 95% CI, 3.2-3.5 points vs 2.5 points; 95% CI, 2.4-2.6 points; P < .001; low-impact label: 3.7 points; 95% CI, 3.5-3.8 points vs 2.6 points; 95% CI, 2.5-2.7 points; P < .001; high-impact label: 3.5 points; 95% CI, 3.3-3.6 points vs 2.7 points; 95% CI, 2.6-2.9 points; P < .001). Participants in the high-climate impact label group selected healthier items according to mean (SE) NPI score (54.3 [0.2] points) compared with those in the low-climate impact (53.2 [0.2] points; P < .001) and control (52.9 [0.3] points; P < .001) label groups.

CONCLUSIONS AND RELEVANCE

This randomized clinical trial's findings suggest that climate impact menu labels, especially negatively framed labels highlighting high-climate impact items (ie, red meat), were an effective strategy to reduce red meat selections and encourage more sustainable choices.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05482204.

Low-carbohydrate vegan diets in diabetes for weight loss and sustainability: a randomized controlled trial

BACKGROUND

Low-carbohydrate, high animal fat and protein diets have been promoted for weight loss and diabetes treatment. We therefore tested the effect of a low-carbohydrate vegan diet in diabetes as a potentially healthier and more ecologically sustainable low-carbohydrate option.

OBJECTIVES

We sought to compare the effectiveness of a low-carbohydrate vegan diet with a moderate-carbohydrate vegetarian diet on weight loss and metabolic measures in diabetes.

METHODS

One hundred and sixty-four male and female participants with type 2 diabetes were randomly assigned to advice on either a low-carbohydrate vegan diet, high in canola oil and plant proteins, or a vegetarian therapeutic diet, for 3 mo, with both diets recommended at 60% of calorie requirements. Body weight, fasting blood, blood pressure, and 7-d food records, to estimate potential greenhouse gas emissions, were obtained throughout the study with tests of cholesterol absorption undertaken at baseline and end of study on 50 participants.

RESULTS

Both low-carbohydrate vegan and vegetarian diets similarly but markedly reduced body weight (-5.9 kg; 95% CI: -6.5, -5.28 kg; and -5.23 kg; 95% CI: -5.84, -4.62 kg), glycated hemoglobin (-0.99%; 95% CI: -1.07, -0.9%; and -0.88%; 95% CI: -0.97, -0.8%), systolic blood pressure (-4 mmHg; 95% CI: -7, -2 mmHg; and -6 mmHg; 95% CI: -8, -3 mmHg), and potential greenhouse gas emissions, but only for potential greenhouse gas emissions was there a significant treatment difference of -0.63 kgCO2/d (95% CI: -0.99, -0.27 kgCO2/d) favoring the low-carbohydrate vegan diet.

CONCLUSIONS

Low-carbohydrate vegan and vegetarian diets reduced body weight, improved glycemic control and blood pressure, but the more plant-based diet had greater potential reduction in greenhouse gas emissions.Trial registration number: clinicaltrials.gov identifier NCT02245399.

Effectiveness of current protein recommendations in adolescent athletes on a low-carbon diet

Adolescent athletes require adequate energy and nutrient supply to support growth, development, and the demands associated with exercise and training. However, they are susceptible to nutritional inadequacies affecting their health and physical performance. Food choices with nutrient adequacy and environmental protection is crucial for a sustainable diet. Therefore, we aimed to assess the adequacy of low-carbon diets to meet the protein requirements of adolescent athletes. Therefore, a cross-sectional observational study was conducted with 91 adolescent athletes from sports clubs in Rio de Janeiro who underwent anthropometric and food consumption assessments. To estimate the environmental impact of anthropogenic activities, the sustainability indicators carbon footprint (CF) and water footprint (WF) were used. The CF of the athlete's diet was compared with the benchmark of 1,571 g CO2eq/cap/d estimated by the World Wildlife Fund (WWF). Protein recommendations according to the American Dietetic Association (ADA) for athletes and protein food groups according to the low-carbon EAT-Lancet reference diet were used as references. The results were stratified by sport modality, age, sex, and income range. The Mann-Whitney test was performed, followed by the Kruskal-Wallis test with Dunn's post-hoc test to assess the differences between groups using the statistical program GraphPad PRISM® version 8.0. CF and WF were directly associated with total energy intake, total protein intake, animal-origin protein intake, and the food groups of meat and eggs. Significant differences were observed in the environmental impact of diet based on sports groups and gender. The athletes' profile with higher environmental impact was male, middle-income class, and of any age group. The quartiles of CF of the overall diets were above the 1,571 g CO2eq/cap/d benchmark. Additionally, ADA's recommended range of daily protein consumption was met by most athletes, even in the lowest quartile of CF. Thus, a diet with a lower environmental impact can meet protein recommendations in adolescent athletes. The results found are of interest to the sports and food industries. It could help in designing a balanced diet for athletes as well as ensure less negative environmental impacts of food production and consumption.

Most plant-based meat alternative buyers also buy meat: an analysis of household demographics, habit formation, and buying behavior among meat alternative buyers

The promise of novel plant-based meat alternatives (PBMAs) to lessen the health and environmental impacts of meat consumption ultimately depend on market acceptance and the extent to which they displace meat in consumers' diets. We use household scanner data to provide an in-depth analysis of consumers' PBMA buying behaviors. PBMAs buyers tend to be young, single, female, college educated, employed, higher income, and non-white. About 20% of consumers purchased a PBMA at least once, and 12% purchased a PBMA on multiple occasions. About 2.79% of households only purchased PBMAs. About 86% of PBMA buyers also bought ground meat; however, PBMA buyers spent about 13% less on ground meat. Interestingly, after a household's first PBMA purchase, ground meat consumption did not fall. The number of households buying a PBMA for the first time fell over the two year period studied, despite the increase in market share in the ground meat market.

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.

Life Cycle Assessment Perspective for Sectoral Adaptation to Climate Change: Environmental Impact Assessment of Pig Production

Growing demand for sustainably driven production systems, especially pork, requires a holistic or system thinking approach. Life Cycle Thinking (LCT) offers a robust methodological background as one of the approaches to achieving system analysis for a product along its lifecycle. On the other hand, Life Cycle Assessment (LCA) can perform state-of-art system analysis characterising its sustainability fronts as a compelling set of tools. Pork, as the most consumed meat across Europe (circa 34 kg per capita per year), compounded with the sector’s contribution to global greenhouse gases (GHG) doubling over the past decade necessitated this research. Our objective was to map hotspots along the value chain and recommend the best available practices for realising the sectoral contribution to carbon neutrality and climate change adaptation. To achieve the objective, we compared organic and conventional production systems by basing our analysis on Recipe midpoint 2016 (H) V1.13 as implemented in OpenLCA 1.10.2 using AGRIBALYSE® 3.0 datasets for eleven indicators. We found that producing 1 kg of pig meat under an organic production system had almost double the environmental impact of conventional systems for land use, water consumption, acidification, and ecotoxicity. Feed production and manure management are the significant hotspots accounting for over 90% of environmental impacts associated with 1 kg pig meat Liveweight (LW) production. Similarly, efficient conventional systems were less harmful to the environment in per capita unit of production and land use compared with organic ones in ten out of the eleven impacts evaluated. Implementing increased efficiency, reduced use of inputs for feed production, and innovative manure management practices with technological potential were some of the best practices the research recommended to realise minimal impacts on the identified hotspots.

Ten-Year Changes in Global Warming Potential of Dietary Patterns Based on Food Consumption in Ontario, Canada

Many studies have evaluated the life cycle environmental impacts of diets based on a single period, but few studies have considered how environmental impacts of diets change over time, even though dietary patterns (DPs) change due to policy and socio-demographic factors. This study evaluated changes in the global warming potential (GWP) of DPs in the province of Ontario, Canada, using a life cycle assessment. We quantified the farm-to-fork GWP of six DPs (Omnivorous, No Pork, No Beef, No Red Meat, Pescatarian, and Vegetarian), using dietary intake data from a 2014 and 2015 survey. Throughout this period, the biggest decrease in GWP was for DPs containing beef, even though these DPs still have the highest GWP (3203 and 2308 kg CO2e, respectively, based on the annual energy intake of one individual). Across all DPs, plant-based proteins contributed less than 5% to GWP, while meat and fish contributed up to 62% of the total GWP. Ten-year GWP reductions are insufficient to meet climate change and other sustainability goals, and major dietary shifts are needed, particularly substituting animal-based proteins with plant-based proteins. To design effective interventions for shifting towards sustainable diets, research is needed to understand how socio-demographic and regional differences influence individuals’ food choices.

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.

Awareness of and reactions to health and environmental harms of red meat among parents in the United States

OBJECTIVE

Evidence of the health and environmental harms of red meat is growing, yet little is known about which harms may be most impactful to include in meat reduction messages. This study examined which harms consumers are most aware of and which most discourage them from wanting to eat red meat.

DESIGN

Within-subjects randomised experiment. Participants responded to questions about their awareness of, and perceived discouragement in response to, eight health and eight environmental harms of red meat presented in random order. Discouragement was assessed on a 1-to-5 Likert-type scale.

SETTING

Online survey.

PARTICIPANTS

544 US parents.

RESULTS

A minority of participants reported awareness that red meat contributes to health harms (ranging from 8 % awareness for prostate cancer to 28 % for heart disease) or environmental harms (ranging from 13 % for water shortages and deforestation to 22 % for climate change). Among specific harms, heart disease elicited the most discouragement (mean = 2·82 out of 5), followed by early death (mean = 2·79) and plants and animals going extinct (mean = 2·75), though most harms elicited similar discouragement (range of means, 2·60-2·82). In multivariable analyses, participants who were younger, identified as Black, identified as politically liberal, had higher general perceptions that red meat is bad for health and had higher usual red meat consumption reported being more discouraged from wanting to eat red meat in response to health and environmental harms (all P < 0·05).

CONCLUSIONS

Messages about a variety of health and environmental harms of red meat could inform consumers and motivate reductions in red meat consumption.

Do diets with higher carbon footprints increase the risk of mortality? A population-based simulation study using self-selected diets from the USA

OBJECTIVE

Are diets with a greater environmental impact less healthy? This is a key question for nutrition policy, but previous research does not provide a clear answer. To address this, our objective here was to test whether American diets with the highest carbon footprints predicted greater population-level mortality from diet-related chronic disease than those with the lowest.

DESIGN

Baseline dietary recall data were combined with a database of greenhouse gases emitted in the production of foods to estimate a carbon footprint for each diet. Diets were ranked on their carbon footprints and those in the highest and lowest quintiles were studied here. Preventable Risk Integrated Model (PRIME), an epidemiological modelling software, was used to assess CVD and cancer mortality for a simulated dietary change from the highest to the lowest impact diets. The diet-mortality relationships used by PRIME came from published meta-analyses of randomised controlled trials and prospective cohort studies.

SETTING

USA.

PARTICIPANTS

Baseline diets came from adults (n 12 865) in the nationally representative 2005-2010 National Health and Nutrition Examination Survey.

RESULTS

A simulated change at the population level from the highest to the lowest carbon footprint diets resulted in 23 739 (95 % CI 20 349, 27 065) fewer annual deaths from CVD and cancer. This represents a 1·83 % (95 % CI 1·57 %, 2·08 %) decrease in total deaths. About 95 % of deaths averted were from CVD.

CONCLUSIONS

Diets with the highest carbon footprints were associated with a greater risk of mortality than the lowest, suggesting that dietary guidance could incorporate sustainability information to reinforce health messaging.

Greenhouse Gas Emissions Associated With the Mexican Diet: Identifying Social Groups With the Largest Carbon Footprint

Background

Most studies of the climate footprint of diets have been conducted in countries in the global north, but the majority of the world population lives in global south countries. We estimated total dietary greenhouse gas emissions (GHGE) in Mexico, examined the contribution of major food and beverage groups, and assessed variation across social groups.

Methods

We linked individual-level dietary data from the Mexican National Health and Nutrition Survey 2018 to the SHARP Indicators Database, containing GHGE estimates for 182 primary food and beverages.

Results

Mean dietary GHGE was 3.9 kg of carbon dioxide equivalent per person per day. Dietary GHGE is highest among those in young adulthood and middle age versus adolescents and older adults, and among males, those with higher educational attainment, higher socioeconomic status, that do not speak an indigenous language, and that live in urban areas.

Conclusion

The Mexican diet has a much lower carbon footprint than diets in other Latin American countries for which such estimates are available. In contrast to patterns observed in Argentina and Brazil, dietary GHGE was lowest in those in lower socioeconomic and educational strata and in rural areas. A better understanding of the differences in diet sustainability between and within countries will be needed for developing global and local strategies that meet the environmental sustainability goals.

Changing dietary patterns is necessary to improve the sustainability of Western diets from a One Health perspective

Western diets are associated with multiple environmental impacts and risks to human health. European countries are gradually taking action towards the Farm to Fork Strategy, embracing a Life Cycle Assessment (LCA) perspective to promote the sustainability of food production and consumption. Although LCA enables the comprehensive assessment of environmental impacts, diet-related human health and animal welfare impacts are often underrepresented. This study proposes integrating additional indicators into LCA to evaluate the sustainability of diets under the One Health (OH) approach, which holistically considers interlinked complex health issues between humans, animals and the environment. Human health loss is estimated according to risk factors for non-communicable diseases; while animal welfare is measured as animal life years suffered, loss of animal lives and loss of morally-adjusted animal lives. The extended LCA framework is applied to men and women's reference diets in the German federal state of North Rhine-Westphalia (NRW); compared to three optimized dietary scenarios under nutritional constraints: 1) the national dietary guidelines, 2) a vegan diet (VD) and 3) a Mediterranean diet (MD). Men's reference diet causes greater impacts than women's across OH dimensions due to the higher food consumption, especially of ready-to-eat meals, sausages, meat, and sweetened and alcoholic beverages. Both reference diets are associated with risk factors for cardiovascular diseases, diabetes, stroke and neoplasms. Besides meat, consumption of honey, fish and seafood has the greatest impact on animal welfare, because of the high number of individuals involved. Alternative diets improve the sustainability of food consumption in NRW, although trade-offs arise: MD worsens animal suffering due to the higher fish intake; water use increases in both VD and MD due the higher intake of nuts and vegetables. Results highlight the importance of including animal welfare and human health indicators in LCA to better elucidate the potential impacts of diets characterized by the high intake of animal products, from a OH perspective.

Adherence to the Mediterranean diet and its association with environmental footprints among women of childbearing age in the United Arab Emirates

PURPOSE

To examine the association of adherence to the Mediterranean Diet (MD) with Environmental Footprints (EFPs) among women of childbearing age in the United Arab Emirates (UAE).

METHODS

Data belonging to a nationally representative sample of 482 women (19-50 years) were derived from a previous survey in the UAE. In face-to-face interviews, participants completed questionnaires addressing sociodemographic, physical activity, and dietary intake characteristics; the latter assessed using a multiple pass 24-h recall. The composite Mediterranean (c-MED) index was used to examine the adherence to the MD. Metrics for the EFPs (water use, energy use, and GHG emissions) were calculated using Life Cycle Analyses. Descriptive statistics and linear regressions were used in data analysis.

RESULTS

In the study sample, the distribution of the c-MED scores was skewed to the right, indicating a low adherence to the MD. The lowest contributions to the total c-MED score were observed for legumes (2.9%) and olive oil (1.8%). The EFPs associated with food consumption per 1000 kcal were: water use: 1256.89 ± 544.95 L/day; energy use: 18.01 ± 7.85 MJ/day, and GHG: 2.46 ± 1.46 kg CO_{2 eq}/day. After adjustment for age, energy intake, and potential confounders, being adherent to the MD was associated with 540.57 [95% CI (- 726.6; - 354.54)] units decrease in water use and 0.94 units decrease in GHG emissions [95% CI (- 1.45; - 0.43)].

CONCLUSIONS

The findings of this study revealed an inverse association between adherence to the MD and EFPs. As such, the MD may represent a promising dietary strategy to improve health outcomes and reduce the environmental impact. Public health programs addressing the low adherence to the MD among women of childbearing age in the UAE are warranted.

How Americans eat red and processed meat: an analysis of the contribution of thirteen different food groups

OBJECTIVE

Dietary patterns characterised by high intake of red and processed meat are associated with detrimental health and environmental outcomes. To better understand how Americans consume red and processed meat, this study examined the food groups that are the greatest contributors to red and processed meat intake in US diets.

DESIGN

Cross-sectional analysis of total red and processed meat, unprocessed red meat and processed meat using data from the National Health and Nutrition Examination Survey (2015-2016 and 2017-2018). Items containing red or processed meat were classified into thirteen mutually exclusive food groups. For highly consumed food groups (≥10 % of meat intake), contribution to meat intake was further assessed by source, sex, income and education.

SETTING

Nationally representative sample of the US population.

PARTICIPANTS

Teens (aged 12-19 years) and adults (aged ≥20 years) who reported meat consumption (n 8178).

RESULTS

Meat mixed dishes (18·6 % (95 % CI 16·2, 20·9)), burgers (17·3 % (95 % CI 15·3, 19·3)) and beef excluding ground (17·0 % (95 % CI 13·8, 20·1)) were the top contributors to unprocessed red meat intake. For processed meat, four food groups made up about four-fifths of total intake: cold cuts and cured meats (37·7 % (95 % CI 34·6, 40·8)), sausages and frankfurters (20·3 % (95 % CI 18·6, 22·0)), bacon (14·0 % (95 % CI 12·3, 15·6)) and pizza (10·1 % (95 % CI 8·7, 11·5)). Fast-food restaurants were the top source for burgers and pizza, whereas stores were the top source for all other highly consumed food groups. Few differences were seen in patterns of intake by sociodemographic characteristics.

CONCLUSIONS

No single food group accounts for a majority of meat intake in the USA. Many behaviour change opportunities for healthier, more sustainable substitutions exist.

Driving commitment to sustainable food policies within the framework of American and European dietary guidelines

Diet and nutrition are essential factors in promoting good health throughout life. Their role as determinants of chronic non-communicable diseases is widely recognized. Additionally, the demand for food involves relevant environmental burdens that have to be taken into account on the way to achieving the Sustainable Development Goals. As an important part of nutrition policy, food-based dietary guidelines (FBDGs) have been revised. The key question is: Are environmental considerations being incorporated into them? To address this issue, we modeled and compared both the main environmental indicators in terms of carbon footprint (CF) and water footprint (WF), and nutritional quality (according to the Nutrient Rich Diet index, NRD9.3 and a health gain score) of dietary guidelines from Northern and Southern Europe and America. Particularly, the FBDGs compared were Dutch Dietary Guidelines (DDG), New Nordic Diet (NND), Spanish Strategy for Nutrition, Physical Activity and Obesity Prevention (NAOS), Mediterranean Diet (MD), Italian Dietary Guidelines (IDG) and American Dietary Guidelines (DGA). The IDG and MD offered the best profiles from a climate change perspective (2.04 and 2.21 kgCO₂eq·day^-1). Overall, DGA had the highest CF (2.98 kgCO₂eq·day^-1). WF presented greater fluctuations, not only due to daily-recommended amounts, but also because of different climate conditions and production systems of the reference countries. Hence, WF ranged from 1760 L·person^-1·day^-1 in IDG to 3181 L·person^-1·day^-1 in NAOS. Finally, the nutritional value of MD, which had the highest NRD9.3 (477) and health gain score (178), has been demonstrated when the comparison was made with DDG, the one with the lowest health gain score (97) and DGA, the worst in terms of NRD9.3 (391). To go ahead of the FBDGs that bet on all dimensions of sustainability, multi-criteria analysis is needed. Nutrition and environmental performance are not the only aspects of the problem; economy and sociocultural variables should be considered.

Towards a More Sustainable Urban Food System—Carbon Emissions Assessment of a Diet Transition with the FEWprint Platform

The production, processing, and transportation of food, in particular animal-based products, imposes great environmental burden on the planet. The current food supply system often constitutes a considerable part of the total carbon emissions of urban communities in industrialised cities. Urban food production (UFP) is a method that can potentially diminish food emissions. In parallel, a shift towards a predominantly plant-based diet that meets the nutritional protein intake is an effective method to curtail carbon emissions from food. Considering the high land use associated with the production of animal-based products, such a shift will prompt a community food demand that is more inclined to be satisfied with local production. Therefore, during the design process of a future low-carbon city, the combined application of both methods is worth exploring. This work introduces, describes, and demonstrates the diet shift component of the FEWprint platform, a user friendly UFP assessment platform for designers that is constructed around the broader three-pronged strategy of evaluation, shift, and design. For three neighborhoods, in Amsterdam, Belfast, and Detroit, the contextual consumption and country-specific environmental footprint data are applied to simulate a theoretical community-wide diet shift from a conventional to a vegan diet, whilst maintaining protein intake equilibrium. The results show that in total terms, the largest carbon mitigation potential awaits in Detroit (−916 kg CO2eq/cap/year), followed by Belfast (−866 kg) and Amsterdam (−509 kg). In relative terms, the carbon reduction potential is largest in Belfast (−25%), followed by Amsterdam (−15%) and Detroit (−7%). The FEWprint can be used to generate preliminary figures on the carbon implications of dietary adaptations and can be employed to give a first indication of the potential of UFP in urban communities.

Cooking at Home, Fast Food, Meat Consumption, and Dietary Carbon Footprint among US Adults

Shifting consumer behavior towards more sustainable diets can benefit environmental sustainability and human health. Although more frequent home cooking is associated with a better diet quality and fast-food consumption with worse diet quality, the environmental impact of diets based on frequency of cooking or eating fast food is not well understood. The objective of this study was to investigate whether the frequency of cooking dinner at home or eating fast food is associated with dietary greenhouse gas emissions (GHGE). We linked 24-h dietary recall data from adult respondents in the 2007-2010 National Health and Nutrition Examination Survey (NHANES) (N = 11,469) to a database of GHGE factors to obtain a measure of dietary GHGE (kgCO2-eq/2000 kcal) (the sum of emissions released in the production of food for an individual's diet), adjusted by energy intake (kgCO2-eq/2000 kcal). We examined associations between frequency of cooking dinner (the only meal for which cooking frequency was measured), frequency of eating fast food, and dietary GHGE and protein sources (beef, pork, poultry, other meat, and fish and seafood (g/2000 kcal)) using generalized linearized regression models that controlled for age, sex, and other socio-economic characteristics. Greater cooking frequency was associated with higher dietary GHGE. In fully adjusted models, cooking 5-6 times/week was associated with an additional 0.058 kgCO2-eq/2000 kcal (SE 0.033) and cooking 7 times/week was associated with an additional 0.057 kgCO2-eq/2000 kcal (SE 0.027) when compared to cooking 0-2 times/week. Individuals in households who cooked dinner more frequently consumed significantly more meat, poultry, and fish (cooking 7 times/week: 148.7 g/2000 kcal vs. cooking 0-2 times/week: 135.4 g/2000 kcal, p-trend = 0.005), which could explain the association with a higher carbon footprint diet. There were few associations of note between fast-food frequency and GHGE. Policies and interventions that reduce consumption of meat and increase consumption of plants when both cooking meals at home and eating meals out are needed to shift toward diets that will be beneficial for both human health and the health of the planet.

Single-item substitutions can substantially reduce the carbon and water scarcity footprints of US diets

BACKGROUND

Human food systems substantially affect the environment, but the impacts vary widely by food. Guidance to individuals to reduce their dietary impacts would benefit from easy advice, but little is known about the specific population impacts of simple changes on self-selected diets.

OBJECTIVES

The objective was to estimate the potential impact of a single dietary substitution on the carbon and water scarcity footprints of self-selected diets in the United States.

METHODS

This cross-sectional modeling study used 24-h dietary recall data from the 2005-2010 waves of the NHANES. Greenhouse gas emissions (GHGE) in the production of foods as well as irrigated water use, characterized by its relative scarcity at production locations, were matched to all foods in the recalls using previously developed databases. Impacts were summed to create carbon and water scarcity footprints for diets (n  = 16,800) of adults aged >18 y. Diet quality was assessed using the Healthy Eating Index (HEI). Foods with the highest impact on GHGE and selected additional foods were substituted for calorically equivalent, less impactful items. Footprints were calculated before and after these hypothetical substitutions.

RESULTS

The highest impact foods were all beef items, and 19.8% of individuals consumed them (n = 3320). After substitution of these items with poultry or pork, the mean carbon and water scarcity footprints among those with substitutions significantly decreased (P < 0.001) by 48.4 ± 0.6% and 29.9 ± 0.4%, respectively. Across the entire sample, these represented mean reductions of 9.6 ± 0.3% and 5.9 ± 0.2%, respectively. The mean HEI after substitutions was 3.6 ± 0.1% higher than before (P < 0.001). None of the selected additional foods had population impacts as large as the beef substitutions.

CONCLUSIONS

Simple substitutions can be made in individuals' diets to substantially reduce their carbon and water scarcity footprints without sacrificing dietary quality. Such substitutions may be easier to promote than complex dietary patterns.

Quality and environmental footprints of diets by socio-economic status in Argentina

Food consumption and production plays a major role on human health and environmental sustainability. In addition, socio-economic status (SES) could be an important determinant on these impacts. Here we investigated the quality and environmental footprints of diets of different SES in Argentina. Dietary data was obtained from a recent national-wide representative survey (21,547 households), and individual intake was estimated by applying the Adult-Male Equivalent (AME) approach. Dietary quality was assessed by comparing the apparent consumption of foods and nutrients with the level of intake associated with the lowest risk of mortality, and applying the Alternate Healthy Eating Index 2010 (AHEI-2010). The environmental footprints were assessed with a set of six environmental indicators: greenhouse gas (GHG) emissions, total land occupation, cropland demand, fossil energy use, freshwater consumption and eutrophying emissions. Per capita total expenditure was utilized as an indicator of SES. We found a suboptimal intake of healthy and excess of unhealthy foods and nutrients in all SES, as well as a low AHEI-2010 score (34.7 ± 3.56 over 100). Regarding environmental footprints per AME, we estimated 8.91 ± 2.49 kg CO₂-eq/day for GHG emissions, 9.30 ± 2.93 MJ/day for fossil energy use, 54.2 ± 14.8 m²/day for total land occupation, 7.07 ± 1.90 m²/day for cropland demand, 205 ± 65.3 L/day for freshwater consumption and 19.8 ± 6.43 g PO₄-eq/day for eutrophying emissions. The Argentinian diet was found to be both unhealthy and unsustainable in all socio-economic levels.

Carbon footprint of the Brazilian diet

OBJECTIVE

To estimate the carbon footprint of the Brazilian diet and of sociodemographic strata of this population.

METHODS

Carbon footprint of the diet was estimated based on data from two 24-hour diet records, obtained in 2008 and 2009, from a probabilistic sample of the Brazilian population aged 10 years and over (n = 34,003) and on environmental impact coefficients of food and culinary preparations consumed in Brazil (gCO2e/kg). Means with 95% confidence intervals of food consumption (kcal/person/day) and the carbon footprint of the diet (gCO2e/person/day and in gCO2e/2,000kcal) were calculated for the population as a whole and for strata according to sex, age, income, education, macro-regions and Federative Unit. Linear regression models were used to identify significant differences (p < 0.05) in the dietary carbon footprint of different sociodemographic strata.

RESULTS

The average carbon footprint of the Brazilian diet was 4,489gCO2e/person/day. It was higher for males, for the age group from 20 to 49 years and for the North and Midwest regions, and tended to increase with income and education. The pattern of association of footprint with sociodemographic variables did not change substantially with adjustment for differences in the amount of food consumed, except for a reduction in the relative excess of the footprint among males and an increase in the relative excess of the footprint in the Midwest region.

CONCLUSION

The carbon footprint of the Brazilian diet exceeds by about 30% the footprint of the human diet, which could simultaneously meet the nutritional requirements of a healthy diet and the global goal of containing the increase in the planet's average temperature. The pattern of association of this footprint with sociodemographic variables can help identify priority targets for public actions aimed at reducing the environmental impacts of food consumption in Brazil.

Large-Scale Microanalysis of U.S. Household Food Carbon Footprints and Reduction Potentials

Promoting sustainable food consumption is critical to meet the United Nation's Sustainable Development Goals. The existing research using average diets and the individual one-day diet recall data to obtain insights into food carbon footprints (CFs) may neglect the diverse food purchasing patterns in different households (HHs). In this paper, we analyzed detailed grocery shopping records of 57,578 U.S. HHs to evaluate the associated food CFs. The cradle-to-farm-gate CFs of 83 food items were calculated using a process-based life cycle assessment model adapted to the U.S. condition. Using the CF of a healthy and sustainable diet as the benchmark, we quantified the CF reduction potentials for each HH. Our results suggest three key strategies to reduce HH food CFs: (1) lowering the over-purchasing in small (one- or two-person) HHs can achieve two-thirds of the recognized carbon emission reduction potentials; (2) reducing the intake of snacks, ready-made food, and drinks leads to as much as, if not more, carbon emission reduction than changing diets; and (3) more attention needs to be paid to reduce the carbon intensity of food items with large purchased volume.

Differences in Environmental Impact between Plant-Based Alternatives to Dairy and Dairy Products: A Systematic Literature Review

A large body of research suggests a more plant-based diet, including a switch to plant-based alternatives to dairy, is needed for lowering human-induced climate change as well as land and water use. With the help of a systematic literature review, we analyzed data from 21 peer-reviewed articles about the differences in emissions and resources used between various plant-based alternatives to dairy and dairy products. Emissions included were greenhouse gases, acidifying, eutrophicating, and ozone-depleting substances, and resource use included water, energy, and land. The results are presented as the quotients of the ratios of plant-based alternatives to dairy and dairy products. The comparison shows that the plant-based dairy alternatives have lower, or much lower, impacts in almost all cases, with two exceptions: water use for almond drinks (several studies) and emissions of ozone-depleting substances for margarine (one study). There is a lack of data concerning impacts other than greenhouse gas emissions for plant-based cheese alternatives; and in general, emissions of greenhouse gases are more highly covered than other impacts. In the quest for a swift transition to a low carbon economy, however, there is already enough evidence to proceed with a dietary change involving switching dairy products to plant-based alternatives.

A Life Cycle Assessment Approach for Vegetables in Large-, Mid-, and Small-Scale Food Systems in the Midwest US

Although vegetables are important for healthy diets, there are concerns about the sustainability of food systems that provide them. For example, half of fresh-market vegetables sold in the United States (US) are produced in California, leading to negative impacts associated with transportation. In Iowa, the focus of this study, 90% of food is imported from outside the state. Previous life cycle assessment (LCA) studies indicate that food consumption patterns affect global warming potential (GWP), with animal products having more negative impacts than vegetables. However, studies focused on how GWP, energy, and water use vary between food systems and vegetable types are less common. The purpose of this study was to examine these environmental impacts to inform decisions to buy locally or grow vegetables in the Midwest. We used a life cycle approach to examine three food systems (large-, mid-, and small-scale) and 18 vegetables commonly grown in/near Des Moines, Iowa. We found differences in GWP, energy, and water use (p ≤ 0.001 for each) for the three food systems with the large-scale scenario producing more emissions. There were also differences among vegetables, with the highest GWP for romaine lettuce (1.92 CO2eq/kg vegetable) approximately three times that of leaf lettuce (0.65 CO2eq/kg vegetable) at the large scale. Hotspots and tradeoffs between GWP, energy, and water use were also identified and could inform vegetable production/consumption based on carbon and water use footprints for the US Midwest.

Decoupling Energy, Water, and Food Resources Production from GHG Emissions: A Footprint Perspective Review of Africa from 1990 to 2017

Decoupling energy, water, and food (EWF) consumption and production from GHG emissions could be an important strategy for achieving the UN Sustainable Development Goals (SDGs), especially SDG 2 (Zero Hunger), SDG 6 (Clean Water and Sanitation), and SDG 7 (Clean and Affordable Energy) in Africa. This study applies Tapio’s decoupling method to analyze the relationship between GHG emissions and EWF resources use in 15 African countries over the period 1990–2017. The results show a remarkable relationship, which includes the contamination of EWF by GHG emissions, that mostly exhibits unsatisfactory decoupling state to satisfactory decoupling over a period of several years. The decoupling of water and energy resources from GHG emissions in most countries of Africa has not been able to reach an excellent decoupling state or a strong positive decoupling state. This requires countries in Africa to support environmentally friendly water and energy infrastructures and to promote an integrated, mutually managed, whole resource interaction system. The study also highlights the importance of tracking sources of GHG emissions, whether within individual resource sector activities or across resources to each other.

Toward a Healthy and Environmentally Sustainable Campus Food Environment: A Scoping Review of Postsecondary Food Interventions

Interventions are urgently needed to transform the food system and shift population eating patterns toward those consistent with human health and environmental sustainability. Postsecondary campuses offer a naturalistic setting to trial interventions to improve the health of students and provide insight into interventions that could be scaled up in other settings. However, the current state of the evidence on interventions to support healthy and environmentally sustainable eating within postsecondary settings is not well understood. A scoping review of food- and nutrition-related interventions implemented and evaluated on postsecondary campuses was conducted to determine the extent to which they integrate considerations related to human health and/or environmental sustainability, as well as to synthesize the nature and effectiveness of interventions and to identify knowledge gaps in the literature. MEDLINE (via PubMed), CINAHL, Scopus, and ERIC were searched to identify articles describing naturalistic campus food interventions published in English from January 2015 to December 2019. Data were extracted from 38 peer-reviewed articles, representing 37 unique interventions, and synthesized according to policy domains within the World Cancer Research Foundation's NOURISHING framework. Most interventions were focused on supporting human health, whereas considerations related to environmental sustainability were minimal. Interventions to support human health primarily sought to increase nutrition knowledge or to make complementary shifts in food environments, such as through nutrition labeling at point of purchase. Interventions to support environmental sustainability often focused on reducing food waste and few emphasized consumption patterns with lower environmental impacts. The implementation of integrated approaches considering the complexity and interconnectivity of human and planetary health is needed. Such approaches must go beyond the individual to alter the structural determinants that shape our food system and eating patterns.

Shifts towards healthy diets in the US can reduce environmental impacts but would be unaffordable for poorer minorities

Environmental implications of food choice are the focus of increasingly extensive research, but less is known about the impacts of dietary patterns of different socio-economic groups of a country, and the trade-offs between nutritional quality and environmental impacts of diet within those groups. We evaluate the impacts of US household dietary patterns on greenhouse gas emissions, blue water footprint, land use and energy consumption across supply chains using an environmentally extended input-output analysis. We compare the nutritional quality of these dietary patterns using healthy eating index scores across individuals' income and other socio-economic characteristics. Individuals with higher income or education levels are more likely to adopt healthier diets but are also responsible for larger environmental impacts of diet primarily due to a higher consumption of dairy and livestock products, seafood and items with lower energy density but higher nutrient density. Our optimization shows that a healthy diet with lower environmental impacts is achievable within current food budgets for almost 95% of people, and results in average decreases of 2% in food-related greenhouse gas emissions, 24% in land use and 4% in energy consumption, but a 28% increase in blue water consumption. However, such dietary patterns are unaffordable for 38% of Black and Hispanic individuals in the lowest income and education groups. Policies that affect income and food prices making nutritious food more affordable would be needed to achieve better nutrition and improved environmental outcomes simultaneously, particularly for more vulnerable socio-economic groups.

Small targeted dietary changes can yield substantial gains for human health and the environment

To identify environmentally sustainable foods that promote health, we combined nutritional health-based and 18 environmental indicators to evaluate, classify and prioritize individual foods. Specifically for nutrition, we developed the Health Nutritional Index to quantify marginal health effects in minutes of healthy life gained or lost of 5,853 foods in the US diet, ranging from 74 min lost to 80 min gained per serving. Environmental impacts showed large variations and were found to be correlated with global warming, except those related to water use. Our analysis also indicated that substituting only 10% of daily caloric intake from beef and processed meat for fruits, vegetables, nuts, legumes and selected seafood could offer substantial health improvements of 48 min gained per person per day and a 33% reduction in dietary carbon footprint.

Data Integration for Diet Sustainability Analyses

Diet sustainability analyses are stronger when they incorporate multiple food systems domains, disciplines, scales, and time/space dimensions into a common modeling framework. Few analyses do this well: there are large gaps in food systems data in many regions, accessing private and some public data can be difficult, and there are analytical challenges, such as creating linkages across datasets and using complex analytical methods. This article summarizes key data sources across multiple domains of food system sustainability (nutrition, economic, environment) and describes methods and tools for integrating them into a common analytic framework. Our focus is the United States because of the large number of publicly available and highly disaggregated datasets. Thematically, we focus on linkages that exist between environmental and economic datasets to nutrition, which can be used to estimate the cost and agricultural resource use of food waste, interrelationships between healthy eating and climate impacts, diets optimized for cost, nutrition, and environmental impacts, and others. The limitations of these approaches and data sources are described next. By enhancing data integration across these fields, researchers can be better equipped to promote policy for sustainable 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.