Dietary Carbon Research Articles

From Boomers to Zoomers: Generational Differences in US Dietary Carbon Footprints

From Boomers to Zoomers: Generational Differences in US Dietary Carbon Footprints

Analyzing the dietary carbon footprint as a sustainable diet marker in Turkish adults: A cross-sectional study

Aims: This study planned to investigate the characteristics of the diet and its contribution to the carbon footprint-the greenhouse gas emission (GHGE)’s. Material and methods: Data were collected through face-to-face interview method via a questionnaire including socio-demographic information, anthropometric measurements, Three-Factor Eating Questionarre-21, and 24-hour recall food consumption record. Results: This cross-sectional study was conducted with 619 adults (M = 266 (43%), F = 353 (57.0%)) aged 18-64 years. The carbon footprint value of the overall diet was 3.84 ± 0.1 kg CO2-eq per person per day and 2.10 ± 1.2 kg CO2-eq per 1,000 kcal. Meat and dairy groups are the major contributors to carbon footprint (34.8%, and 18.9%, respectively). Uncontrolled eating scores were higher in the highest quantile (Q5) group for the carbon footprint (CO2-eq/kg) group (p

Implications of dietary carbon incorporation in fish carbonates for the global carbon cycle

Marine bony fish are important participants in Earth's carbon cycle through their contributions to the biological pump and the marine inorganic carbon cycle. However, uncertainties in the composition and magnitude of fish contributions preclude their integration into fully coupled carbon-climate models. Here, we consider recent upwards revisions to global fish biomass estimates (2.7–9.5×) and provide new stable carbon isotope measurements that show marine fish are prodigious producers of carbonate with unique composition. Assuming the median increase (4.17×) in fish biomass estimates is linearly reflected in fish carbonate (ichthyocarbonate) production rate, marine fish are estimated to produce between 1.43 and 3.99 Pg CaCO3 yr−1, but potentially as much as 9.03 Pg CaCO3 yr−1. Thus, marine fish carbonate production is equivalent to or potentially higher than contributions by coccolithophores or pelagic foraminifera. New stable carbon isotope analyses indicate that a significant proportion of ichthyocarbonate is derived from dietary carbon, rather than seawater dissolved inorganic carbon. Using a statistical mixing model to derive source contributions, we estimate ichthyocarbonate contains up to 81 % dietary carbon, with average compositions of 28–56 %, standing in contrast to contents <10 % in other biogenic carbonate minerals. Results also indicate ichthyocarbonate contains 5.5–40.4 % total organic carbon. When scaled to the median revised global production of ichthyocarbonate, an additional 0.08 to 1.61 Pg C yr−1 can potentially be added to estimates of fish contributions to the biological pump, significantly increasing marine fish contributions to total surface carbon export. Our integration of geochemical and physiological analyses identifies an overlooked link between carbonate production and the biological pump. Since ichthyocarbonate production is anticipated to increase with climate change scenarios, due to ocean warming and acidification, these results emphasize the importance of quantitative understanding of the multifaceted role of marine fish in the global carbon cycle.

Enigmatic carbonate isotope values in shark teeth: Evidence for environmental and dietary controls

Shark teeth are abundant in the fossil record and integrate physiological information, ecological interactions, and paleo-oceanographic conditions in their chemistry. Fossil shark teeth are well suited for stable isotope analysis because their enameloid is resistant to diagenetic alteration due to its high chemical stability. Although often used in paleoecological studies of mammals, carbonate carbon isotope compositions (δ13CCO3) in shark enameloid have remained enigmatic. Here, we investigate multiple stable isotope systems (δ13Corg, δ13CCO3, δ18OCO3, δ18OPO4) within modern shark teeth to determine relationships between the different systems and build an interpretative framework for future studies of both modern and fossil sharks. There is a weaker than expected correlation between δ18OPO4 and δ18OCO3 values in modern shark teeth (r2 = 0.44), which contrasts with mammalian studies to date and suggests this metric is not an appropriate test for diagenetic alteration in fossil shark teeth. Organic carbon isotope composition (δ13Corg) measured from modern dental collagen ranges from −16.0‰ to −10.8‰. The enameloid δ13CCO3 values we measured are much higher than collagen, ranging from −6.0‰ to 10.3‰, and there is no direct relationship between δ13Corg and δ13CCO3 values in shark teeth. Instead, we found the fractionation (ε) between δ13Corg and δ13CCO3 values to correspond with δ18OCO3 values but not δ18OPO4 values. This could be due to the carbon source in shark enameloid being partitioned between dietary carbon and dissolved inorganic carbon (DIC) or physiological differences in the tooth formation process changing the fractionation of carbonate isotopes. We applied the fractionation factor from modern teeth to carbonate isotope compositions of fossil shark teeth to predict δ13Corg values. Although the carbon sources to shark enameloid carbonate needs further investigation, our results suggest that fossil shark teeth could provide insights into carbon cycling of ancient marine ecosystems.

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.

Geographic variability in the Chilean dietary carbon footprint: Major food contributors and associated factors

Anthropogenic greenhouse gas emissions (GHGE) are behind climate change. In Chile, food system is the second source of GHGE. Changing Chileans dietary patterns is key to reducing such emissions. There is geographic variability in terms of dietary patterns within the country. Here we investigated the dietary GHGE in five different geographical zones, along with the main contributing food groups and socio-demographic variables. Data for 4676 individuals were obtained from the 2010–2011 National Survey of Food Consumption. The carbon footprint value of each food was obtained from studies using life cycle assessment methodology. Median and percentiles of dietary GHGE were calculated, expressed in kilograms of carbon dioxide equivalent per person per day (kgCO2eq/person/d) and compared among zones by Kruskal-Wallis and Dunn's tests. Logistic regression models were fitted to analyzed associations among the variables of interest and quartiles of GHGE. Diet-related GHGE ranged from 3.50 (2.34–5.12) in the North-Central Zone to 4.66 (2.89–6.69) kgCO2eq/person/d in the South zone. Meat accounted for 53–58% of the GHGE in all the zones, followed by dairy products with 12–13%. Higher GHGE were significantly associated with energy intake (kcal/d) in all of the zones, with high socioeconomic level in the North-Central, South and Metropolitan zones, and with urban residence in the South-Central zone. Tailored policies considering geographic variability are warranted to promote healthy and sustainable diets among the Chilean population.

Can we estimate the impact of small targeted dietary changes on human health and environmental sustainability?

A recent analysis by Stylianou et al. (2021) estimated the impact of small dietary changes in the consumption of individual foods on human health and the environment, expressed as minutes of healthy life lost or gained daily combined with dietary carbon footprints. While an appealing concept given its simplistic interpretation, we aim to draw the attention of nLCA practitioners and developers to the significant limitations and uncertainties of this analysis, based on existing evidence. Stylianou's approach produces results that fail to recognize the importance of essential nutrient density and the risks associated with ultra-processed foods, added sugar, and refined starches. The novel impact assessment undoubtedly brings a new perspective to the growing field of nutritional Life Cycle Assessment. However, the authors neglect numerous methodological limitations, fail to direct the readers' attention to (mis)interpretation risks, and draw highly definitive recommendations aiming to directly influence consumer choices and policymaking. Due to extensive data limitations and associated uncertainties in extant databases (both environmental and nutritional), we recommend caution in the use of this (or any other) food classification system to inform consumer behavior, front-of-package labelling, policies, and programs.

A cross-section from the consumer perspective on sustainable nutrition: consumer awareness and motivation status.

Sustainable diets and food production systems are important for healthy life and future generations. This goal should be reachable by consumer motivations. The study aim is the evaluation of awareness and knowledge of sustainability and logo/claims related with sustainability.Participants' knowledge about sustainability definition and logos/claims related to sustainability were assessed by an online-questionnaire. The questionnaire involved the calculation of annual dietary carbon emissions (kg), nitrogen waste (g), and water consumption (L).Four hundred-two volunteers participated in the study (male: 24.9%; female: 75.1). Only 44 participants (10.9%) explained what sustainable nutrition definition, correctly. The rates of knowledge about logos were quite low; 29.4% for organic product logo; 26.6% for Good farming practice logo; 86.1% for Recycle logo; and 8.0% for Eco-label logo, respectively. The education status of participants affected to knowledge of logo/claim ratio (p < 0.05). Ethic production and environmental impact statement information were care of participants' ratio of 33.6% and 34.1%, respectively. The mean dietary carbon emission of participants was 551.0 ± 343.6kg/year, which was 81% of the upper limit (680kg/year). The mean nitrogen waste was 3238.8 ± 4620.9g/year and mean water consumption was 91,538.7 ± 157,537.9 L/year. Mediterranean diet model carbon emission and nitrogen waste were higher than other diet models, omnivore diet models had more water consumption than other diet models. But these differences were not found statistically significant (p > 0.05).Sustainable nutrition can be achieved via consumers' awareness. Food industry and government should encourage the people about promotion of sustainable food preferences.

How sharp is the knife? Herbivore and carnivore sensitivity to resource stoichiometric quality

While understanding feeding preferences of herbivores and carnivores is of major importance in ecology, we still know very little on the sensitivity of different functional groups to suboptimal stoichiometric resource quality. Here, we apply concepts of ecological stoichiometry to shed light on differences in the nutritional requirements of herbivores and carnivores, and to make predictions on the influence of suboptimal resource stoichiometric quality on the fitness of these different consumers to. Herbivores generally experience more variation in the quality of their resource than carnivores do, and these differences have likely shaped the extent to which coping mechanisms have evolved. Consequently, we expect 1) herbivores to maintain their stoichiometric homeostasis over a broader range of resource stoichiometry than carnivores, 2) the threshold elemental ratio (TER), i.e. the dietary carbon to nutrient ratio which maximizes fitness, of herbivores to be higher than that of carnivores, 3) a narrower and sharper knife‐edge response in carnivores than herbivores and 4) asymmetric knife‐edge responses indicating a higher sensitivity to the diet quality that consumers are not used to dealing with, namely nutrient limitation in carnivores and nutrient excess in herbivores. Our study poses that documenting the ranges of resource quality where consumer fitness declines in diverse organisms is a very promising avenue to increase our understanding of community composition and food web functioning.

Isotopic turnover in polar cod (Boreogadus saida) muscle determined through a controlled feeding experiment.

Polar cod (Boreogadus saida) is an important trophic link within Arctic marine food webs and is likely to experience diet shifts in response to climate change. One important tool for assessing organism diet is bulk stable isotope analysis. However, key parameters necessary for interpreting the temporal context of stable isotope values are lacking, especially for Arctic species. This study provides the first experimental determination of isotopic turnover (as half-life) and trophic discrimination factors (TDFs) of both δ13 C and δ15 N in adult polar cod muscle. Using a diet enriched in both 13 C and 15 N, we measured isotopic turnover times of 61 and 49 days for δ13 C and δ15 N, respectively, with metabolism accounting for >94% of the total turnover. These half-life estimates are valid for adult polar cod (>3 years) experiencing little somatic growth. We measured TDFs in our control of 2.6‰ and 3.9‰ for δ13 C and δ15 N, respectively, and we conclude that applying the commonly used TDF of ~1‰ for δ13 C for adult polar cod may lead to misrepresentation of dietary carbon source, while the use of 3.8‰ for δ15 N is appropriate. Based on these results, we recommend that studies investigating seasonal shifts in the diet of adult polar cod sample at temporal intervals of at least 60 days to account for isotopic turnover in polar cod muscle. Although isotopic equilibrium was reached by the fish in this study, it was at substantially lower isotope values than the diet. Additionally, the use of highly enriched algae in the experimental feed caused very high variability in diet isotope values which precluded accurate calculation of TDFs from the enriched fish. As a result of the challenges faced in this study, we discourage the use of highly enriched diets for similar experiments and provide recommendations to guide the design of future isotopic turnover experiments.

Extreme El Niño southern oscillation conditions have contrasting effects on the body condition of five euphausiid species around the northern Antarctic Peninsula during winter

El Niño southern oscillation (ENSO) events drive profound global impacts on marine environments. These events may result in contrasting conditions in the Southern Ocean, with differing effects on euphausiid species because of their diverse life histories, habitats, and feeding ecologies. We conducted oceanographic surveys during winter (2012–2016) around the northern Antarctic Peninsula and examined the dietary carbon sources, trophic position, and body condition of five euphausiid species (Euphausia crystallorophias, E. frigida, E. superba post-larvae and larvae, E. triacantha, and Thysanoessa macrura) in relation to environmental conditions each year. In addition to general patterns among taxa, we focused on how contrasting conditions during an ENSO-neutral year (2014) and an ENSO-positive year (2016) affected the type, quality, and distribution of food resources each year, as well as the body condition of each species. We observed high chlorophyll-a, low salinity, and shallow upper mixed-layer depths in 2014, and low chlorophyll-a, high salinity, and deep upper mixed-layer depths in 2016. Carbon sources varied among years, with most species enriched in δ13C when ENSO conditions were dominant. Trophic position and body condition also varied among years, with different responses among species depending on conditions; inter-annual variation in δ15N was minimal, while E. triacantha was the only species with notably lower body condition in 2016. We conclude that ENSO conditions around the northern Antarctic Peninsula may result in a more favorable feeding environment for all euphausiid species except E. triacantha, which may be the most negatively impacted by the predicted increase in ENSO conditions.

The Dietary Carbon Footprint of Portuguese Adults: Defining and Assessing Mitigation Scenarios for Greenhouse Gas Emissions

The food chain is a large contributor to environmental pollution, especially greenhouse gas emissions, strongly associated with the consumption of animal-based proteins. The understanding of the negative environmental impacts of dietary habits by the population is of the utmost importance to provide the means to effect change to more sustainable eating patterns. The main purpose of this study was to assess the carbon footprint of animal protein consumption in Portugal, while also evaluating six mitigation scenarios aiming to lower greenhouse gas emissions through strategic changes to the animal protein consumption of current dietary habits. Overall, the carbon footprint associated with animal protein consumption is 2.63 kg CO2 eq/(cap⋅day) nationally and 28.4 t CO2 eq/month for the faculty canteen. Meat is by far the largest contributor to the carbon footprint in both cases, with beef being its “hotspot”. All scenarios showed significant reduction potentials, with values ranging from 16% (lower value for both the national case and the faculty canteen) to 71% (faculty canteen). In sum, substantial carbon footprint reductions can be attained if policymakers support the implementation of effective measures to promote a shift in the current animal protein consumption towards more sustainable eating habits.

Dietary carbon loaded with nano-ZnO alters the gut microbiota community to mediate bile acid metabolism and potentiate intestinal immune function in fattening beef cattle

BackgroundTo our knowledge, carbon loaded with nano-ZnO (NZnOC) represents a new nutritional additive for the animal husbandry industry. However, the mechanism by which NZnOC mediates beef cattle growth and intestinal health is not fully understood. This study aimed to investigate the effects of carbon loaded with nano-ZnO (NZnOC) supplementation on growth performance, gut microbiota, bile acid (BAs) metabolism and intestinal immunity in fattening cattle. Twenty cattle (16 ± 0.95 months) were randomly assigned to two dietary groups: CON (control, without feed additive) and NZnOC (diet supplemented with 80 mg NZnOC/kg diet dry matter basic) for 60 d. The colon digesta microbiota composition and BAs concentration were determined by microbiota metagenomics and gas chromatography methods, respectively.ResultsThe results showed that the NZnOC-supplemented cattle had greater final weight, average daily gain and gain-to-feed ratio than those in the CON group. Cattle fed the NZnOC diet had a higher relative abundance of the secondary BAs synthesizing phyla Firmicutes, Tenericutes and Actinobacteria than those fed the CON diet. Dietary supplementation with NZnOC increased the relative abundance of the secondary BAs synthesis microbiota genera Clostridium, Ruminococcus, Eubacterium, and Brevibacillus in colon digesta. Cattle fed the NZnOC diet had increased activities of 3α-hydroxysteroid dehydrogenase (EC: 1.1.1.52) and bile acid-CoA ligase BaiB (EC: 6.2.1.7) in the colon digesta compared with those fed the CON diet. The primary BAs taurocholic acid, taurochenodeoxycholic acid and taurodeoxycholate acid were significantly decreased by dietary NZnOC supplementation, while the secondary BAs deoxycholic acid, taurolithocholic acid, beta-muricholic acid, 12-ketolithocholic acid and ursodeoxycholic acid were significantly increased. Dietary supplementation with NZnOC increased the mRNA abundance of G protein-coupled bile acid receptor 1, protein kinase cAMP-activated catalytic subunit alpha, cyclic-AMP response element binding protein 1 and interleukin (IL)-10 in the colon mucosa of cattle, while the mRNA abundance of tumor necrosis factor and IL-1β were significantly decreased.ConclusionsIn summary, dietary supplementation with NZnOC can facilitate the growth performance and intestinal immune function of cattle by improving BAs metabolism. NZnOC can be supplemented in the diet as a safe regulator of gut microbiota and as a feed additive in the ruminants industry.

Dietary Environmental Footprints and Their Association with Socioeconomic Factors and Food Purchase Practices: BRAZUCA Natal Study.

The analysis of dietary environmental impacts has proven to be an important tool for guiding the adoption of healthier and more sustainable diets. This study aimed to estimate the dietary carbon (CF), water (WF), and ecological (EF) footprints of residents in the city of Natal, Brazil; the study also aimed to verify their association with socioeconomic factors and food purchase practices. This is a cross-sectional study that used dietary data from 411 adults and elderlies, which was collected via a questionnaire that applied to the respondents. The results showed that the dietary CF was 1901.88 g CO2 eq/day/1000 kcal, the WF was 1834.03 L/day/1000 kcal, and the EF was 14.29 m2/day/1000 kcal. The highest environmental footprint values showed an association (p ≤ 0.05) with the factors of male sex, white ethnicity, and higher income and schooling, whereas the lowest environmental footprint values were associated with social vulnerability variables such as female sex, non-white ethnicity, and lower income and schooling (p ≤ 0.05). Moreover, people with lower environmental footprints consumed less fast food, had fewer meals at snack bars, and used food delivery services less often than those with higher footprints. The foods that most contributed to the CFs and WFs were beef and chicken, while fish and beef contribute the most to the EFs. The data in the present study show that a diet with a lower environmental impact is not always equal to a sustainable diet. This relationship is paradoxical and relates to food justice, as people with lower environmental footprint values are the same ones with worse socioeconomic conditions. In this sense, is it essential to consider the influence of the social context when assessing dietary environmental impacts and when assessing actions that promote healthier and more sustainable diets.

An inter-order comparison of copepod fatty acid composition and biosynthesis in response to a long-chain PUFA deficient diet along a temperature gradient

Copepods serve as a major link in marine food webs, bridging the energy transfer from primary producers to higher trophic levels. Oceanic warming is linked to reduced concentrations of essential fatty acids (FA) in phytoplankton, namely eicosapentaenoic acid (EPA, 20:5ω3) and docosahexaenoic acid (DHA, 22:6ω3), and it remains largely unknown if copepods have the capacity to endure. The calanoid Temora longicornis and the harpacticoid Platychelipus littoralis were chosen to analyse their FA and biosynthesis activity in response to a long-chain polyunsaturated FA (LC-PUFA) deficient diet (Dunaliella tertiolecta) along a temperature gradient. Copepods were fed D. tertiolecta labelled with the stable isotope carbon-13 (13C) to quantify carbon assimilation into their total FA and de novo EPA and DHA biosynthesis after 6 days incubated at 11, 14, 17, 20 and 23 °C. The calanoid had increased mortality with warming, whereas the harpacticoid exhibited high survival across the thermal gradient. After the incubation, P. littoralis assimilated minimal amounts of dietary carbon into its total FA in comparison to T. longicornis. T. longicornis depleted their field EPA and DHA stores more rapidly, whereas P. littoralis maintained its relative storage of EPA and DHA and absolute concentrations of DHA. T. longicornis displayed higher fractions of de novo EPA and DHA biosynthesis than P. littoralis at all temperatures, with the exception of DHA at 23 °C. Within our experimental incubation period both species were unable to meaningfully upgrade the LC-PUFA deficient algae to biosynthesize de novo EPA and DHA as a relevant source for higher trophic levels.

Does Short Term Dietary Intervention Change Dietary Carbon Footprint?

In this study, we aimed to observe whether short-term weight loss program changes dietary carbon footprint (CF) and its effect on the risk of chronic disease. This study was carried out between April 2019 and January 2020. Participants received a diet intervention for four weeks. Their anthropometric measurements and food records were evaluated before and at the end of the study. 61 individuals (51 female; 10 male) aged 19-59 years and with a Body Mass Index (BMI) of ≥25 kg/m2. Their dietary CF of sweets/snacks, drinks, potatoes/bread/pasta, meat, and butter/oil also decreased statistically significantly according to the eight major food groups. The total dietary CF increased in this study (P=0.018). This increase resulted from the increase in the consumption of dairy/egg food group. At the end of the study the body weight, BMI, waist, hip and neck circumference, waist-hip ratio, and the waist-height ratio of participants decreased statistically significantly after the weight loss program (P

Application of the Automated Self-Administered 24-Hour (ASA24) Dietary Assessment Tool’s New Carbon Footprint Dataset

ObjectivesIncreasing concern about the environmental impacts of food production has motivated the development of a new dataset of food-related greenhouse gas emissions (GHGE). The dataset integrates with the Automated Self-Administered (ASA24) Dietary Assessment Tool, a popular web-based tool used by researchers. This paper aims to demonstrate the utility of this dataset by assessing the GHGE, or carbon footprint, of a menu from a consumer education program. MethodsThree days of a sample menu (breakfast, lunch, dinner, and snack) from the University of New Hampshire’s Extension program were entered into ASA24. The menu was based on a balanced food pattern with a range of protein sources, including meat and fish. The database of Food Recall Impacts on the Environment for Nutrition and Dietary Studies (dataFRIENDS) was linked, by food code, with the ASA24-2020 items output file. Matches were found for all items except eight spices. Total calories and CO2 equivalents were calculated by meal and day, based on the weight of each food item. Healthy Eating Index (HEI) total and component scores were estimated for each day. Documentation of the development of GHGE data for ASA24 foods and how to use them will be located on NCI’s ASA24 website. ResultsFor the three days, total kcal were 1612,2168, and 1666, and dietary GHGE were 2.2, 3.4, and 3.2 kg CO2-eq. The third day included two types of meat: ground beef, which contributed 40.7% of that day’s carbon footprint; and a turkey patty, which contributed 3.4%. HEI scores for the three days were 94.0, 83.3, and 89.0, varying inversely with dietary GHGE. The day with the largest carbon footprint had the highest total protein component score, yet the lowest seafood and plant protein score. The opposite was true for the day with the smallest carbon footprint. ConclusionsThis paper demonstrates the application of dataFRIENDS, a new resource for ASA24 users to examine dietary carbon footprints and inform the literature on the environmental impact of food choices. The database can be used to examine menus and dietary intake data, and to compare dietary GHGE with diet quality metrics, which may affect individual food choices. Further analyses can provide context for policies regarding sustainability for federal dietary guidance. Funding SourcesNone.

Self-Selected Diets in the US Show a Reduction in Carbon Footprints Over Ten Years

ObjectivesGrowing evidence indicates the need for demand-side changes to global food systems to meet nutritional needs while staying within planetary boundaries. Previous research documented the greenhouse gas emissions (GHGE, or carbon footprint) of self-selected diets in the US from the 2005–2010 National Health and Nutrition Examination Survey (NHANES), but more recent such data do not exist. To address this gap, we assessed the carbon footprint of diets reported in the 2015–2016 NHANES, and analyzed the 10-year trend from the 2005–2006 wave. MethodsFoods eaten by adults (N = 5,060), ages 18 years and older, reported in a one-day 24-hour recall in NHANES 2005–2006 were translated to commodity intakes using recipes from the US Environmental Protection Agency’s Food Commodity Intake Database (FCID). GHGE (kg carbon dioxide equivalents, or CO2-eq, per kg of edible portion) in the production of these commodities were calculated from the database of Food Impacts on the Environment for Linking to Diets (dataFIELD), then summed for each person to get a total one-day dietary carbon footprint. Newly reported foods consumed by adults (N = 4,982) in 2015–2016 required new recipes to be translated to commodity intakes. We developed these recipes by modifying similar existing FCID recipes. If no similar food existed, recipes were constructed using ingredients and proportions from the US Department of Agriculture’s FoodData Central. ResultsMean food-related GHGE decreased 7.9% across the ten-year period, from 4.9 to 4.5 kg CO2-eq/day. Controlling for energy intake, age, gender, race, and income-to-poverty ratio, one-day food-related GHGE were still lower in 2015–2016 than they were in 2005–2006, by 0.3 kg CO2-eq (p < 0.02). ConclusionsThe average carbon footprint of US adults’ self-selected diets has decreased over time. This is a positive development for efforts to slow climate change. However, evidence reported elsewhere shows that US diets do not meet current nutritional recommendations. Additional research is needed to find and encourage “win-win” diets that meet nutritional objectives, while reducing environmental impacts. Funding SourcesWellcome Trust, National Cancer Institute, Health Resources and Services Administration.

Shaping fuel utilization by mitochondria

Mitochondria are central to cellular metabolism. They provide intermediate metabolites that are used in biosynthetic pathways and they process diet-derived nutrients into the energy-rich compound ATP. Mitochondrial ATP biosynthesis is a marvel of thermodynamic efficiency. Via the tricarboxylic acid cycle (TCA) and fatty acid β-oxidation, mitochondria extract electrons from dietary carbon compounds and pass them to nucleotides that ultimately deliver them to the respiratory chain complexes located in invaginations in the inner mitochondrial membrane (IMM) known as cristae. The respiratory chain complexes donate electrons in stepwise redox reactions to molecular oxygen and, with the exception of complex II, use the liberated energy to pump protons across the proton-impermeable IMM, generating a proton electrochemical gradient. This gradient is then utilized by the ATP synthase, which, in a rotary mechanism, catalyzes the formation of the high-energy γ-phosphate chemical bond between ADP and inorganic phosphate. The conversion of the chemical energy of carbon compounds into a physical, vectorial form of energy (the electrochemical gradient) maximizes the yield of the ATP biosynthetic process and is perhaps one of the foundations of life as we know it.

When Less is better: Messages that Present Dietary Carbon Emissions Data at the individual (vs. Aggregate) Level Increase Commitment to Sustainable Beef Consumption

The environmental footprint embedded in the human diet is massive. To convey the enormity of the problem, persuasive environmental messages often report large-scale, aggregate data (such as the billions of tons of greenhouse gases released to the atmosphere annually by the beef industry.) Is this strategy effective? In five studies (total N = 1237), the environmental footprint of beef was presented to participants with either aggregate, nation-level numeric data, or with the same data scaled to the individual level. Across the studies, a clear pattern emerged: Participants who received aggregate-level (versus individual-level) data perceived less of a connection between their behavior and the environment and expressed less intention to curb their meat consumption. These data suggest that aggregate environmental figures, rather than raising urgency, may instead demotivate many message recipients.