Exploring scenarios for the food system-zoonotic risk interface.

The unprecedented economic and health impacts of the COVID-19 pandemic have shown the global necessity of mitigating the underlying drivers of zoonotic spillover events, which occur at the human-wildlife and domesticated animal interface. Spillover events are associated to varying degrees with high habitat fragmentation, biodiversity loss through land use change, high livestock densities, agricultural inputs, and wildlife hunting-all facets of food systems. As such, the structure and characteristics of food systems can be considered key determinants of modern pandemic risks. This means that emerging infectious diseases should be more explicitly addressed in the discourse of food systems to mitigate the likelihood and impacts of spillover events. Here, we adopt a scenario framework to highlight the many connections among food systems, zoonotic diseases, and sustainability. We identify two overarching dimensions: the extent of land use for food production and the agricultural practices employed that shape four archetypal food systems, each with a distinct risk profile with respect to zoonotic spillovers and differing dimensions of sustainability. Prophylactic measures to curb the emergence of zoonotic diseases are therefore closely linked to diets and food policies. Future research directions should explore more closely how they impact the risk of spillover events.

Health and environmental impacts of plant-rich dietary patterns: a US prospective cohort study.

BACKGROUND: Diets that are rich in animal-based foods threaten planetary and human health, but plant-rich diets have varied health and environmental effects. We aimed to characterise a healthy dietary index and three plant-based indices by their environmental impacts and associations with risk of cardiovascular disease. METHODS: In this prospective cohort study, we used data from a food-frequency questionnaire in the US-based Nurses' Health Study II. Participants were categorised by quintiles of four dietary indices, including the alternative healthy eating index-2010 (AHEI), plant-based diet index (PDI), unhealthy PDI, and healthy PDI. We calculated environmental impacts (greenhouse gas emissions and irrigation water, nitrogenous fertiliser, and high-quality cropland needs), and relative risks (RRs) of cardiovascular disease from 1991-2017, comparing quintiles. FINDINGS: We included 90 884 participants in the health-impact analysis and 65 625 participants in the environmental-impact analysis. Comparing the top and bottom quintiles, higher AHEI scores were associated with a decreased cardiovascular disease risk (relative risk 0·77 [95% CI 0·66-0·89]); 30% lower greenhouse gas emissions (Q5 2·6 kg CO2 equivalent vs Q1 3·7 kg CO2 equivalent); and lower fertiliser, cropland, and water needs (all ptrends<0·0001). Similarly, the highest healthy PDI and PDI quintiles were associated with a decreased cardiovascular disease risk (healthy PDI 0·71 [0·60-0·83] and PDI 0·74 [0·63-0·85]) and lower environmental impacts (PDI water needs ptrend=0·0014; all other ptrends<0·0001). Conversely, the highest unhealthy PDI quintile had a higher cardiovascular disease risk compared with the lowest unhealthy PDI quintile (1·15 [1·00-1·33]; ptrend=0·023) and required more cropland (ptrend<0·0001) and fertiliser (ptrend=0·0008). INTERPRETATION: Dietary patterns that are associated with better health had lower greenhouse gas emissions and nitrogenous fertiliser, cropland, and irrigation water needs. Not all plant-based diets conferred the same health and environmental benefits. US dietary guidelines should include nuanced consideration of environmental sustainability. FUNDING: US National Institutes of Health.

Environmental performance of blue foods.

Fish and other aquatic foods (blue foods) present an opportunity for more sustainable diets1,2. Yet comprehensive comparison has been limited due to sparse inclusion of blue foods in environmental impact studies3,4 relative to the vast diversity of production5. Here we provide standardized estimates of greenhouse gas, nitrogen, phosphorus, freshwater and land stressors for species groups covering nearly three quarters of global production. We find that across all blue foods, farmed bivalves and seaweeds generate the lowest stressors. Capture fisheries predominantly generate greenhouse gas emissions, with small pelagic fishes generating lower emissions than all fed aquaculture, but flatfish and crustaceans generating the highest. Among farmed finfish and crustaceans, silver and bighead carps have the lowest greenhouse gas, nitrogen and phosphorus emissions, but highest water use, while farmed salmon and trout use the least land and water. Finally, we model intervention scenarios and find improving feed conversion ratios reduces stressors across all fed groups, increasing fish yield reduces land and water use by up to half, and optimizing gears reduces capture fishery emissions by more than half for some groups. Collectively, our analysis identifies high-performing blue foods, highlights opportunities to improve environmental performance, advances data-poor environmental assessments, and informs sustainable diets.

Small-scale integrated farming systems can abate continental-scale nutrient leakage.

Beef is the most resource intensive of all commonly used food items. Disproportionate synthetic fertilizer use during beef production propels a vigorous one-way factory-to-ocean nutrient flux, which alternative agriculture models strive to rectify by enhancing in-farm biogeochemical cycling. Livestock, especially cattle, are central to these models, which advocates describe as the context most likely to overcome beef's environmental liabilities. Yet the dietary potential of such models is currently poorly known. Here, I thus ask whether nitrogen-sparing agriculture (NSA) can offer a viable alternative to the current US food system. Focusing on the most common eutrophication-causing element, N, I devise a specific model of mixed-use NSA comprising numerous small farms producing human plant-based food and forage, the latter feeding a core intensive beef operation that forgoes synthetic fertilizer and relies only on locally produced manure and N fixers. Assuming the model is deployed throughout the high-quality, precipitation-rich US cropland (delimiting approximately 100 million ha, less than half of today's agricultural land use) and neglecting potential macroeconomic obstacles to wide deployment, I find that NSA could produce a diverse, high-quality nationwide diet distinctly better than today's mean US diet. The model also permits 70%-80% of today's beef consumption, raises today's protein delivery by 5%-40%, and averts approximately 60% of today's fertilizer use and approximately 10% of today's total greenhouse gas emissions. As defined here, NSA is thus potentially a viable, scalable environmentally superior alternative to the current US food system, but only when combined with the commitment to substantially enhance our reliance on plant food.

Reorientation of aquaculture production systems can reduce environmental impacts and improve nutrition security in Bangladesh.

Aquatic foods are a critical source of human nutrition in many developing countries. As a result, declines in wild-caught fish landings threaten nutritionally vulnerable populations. Aquaculture presents an opportunity to meet local demand, but it also places pressure on natural resource inputs and causes a range of environmental impacts. Here, we examine whether current aquaculture systems in Bangladesh can be reoriented to address prevailing nutritional deficiencies while minimizing these environmental impacts. Current fish farming practices, even when optimized, cannot fully supply the same essential micronutrient densities of zinc, iron and calcium as wild-caught fish. However, when the proportion of highly nutrient-dense small indigenous fish species (SIS) was increased to at least 30% of the total output in any of the 14 aquaculture production systems analysed, these systems were able to meet or surpass the nutrient densities of average wild-capture fisheries. Extensive aquaculture systems that co-produce fish and rice had the lowest environmental burdens in six out of seven metrics examined when the composition of all aquaculture systems was modified to include 50% SIS. Nutrition-sensitive aquaculture that provides greater human health benefits and minimizes environmental impacts is a key societal challenge that requires targeted interventions and supportive policies.

Author Correction: Environmentally Optimal, Nutritionally Sound, Protein and Energy Conserving Plant Based Alternatives to U.S. Meat.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Environmentally Optimal, Nutritionally Sound, Protein and Energy Conserving Plant Based Alternatives to U.S. Meat.

Because meat is more resource intensive than vegetal protein sources, replacing it with efficient plant alternatives is potentially desirable, provided these alternatives prove nutritionally sound. We show that protein conserving plant alternatives to meat that rigorously satisfy key nutritional constraints while minimizing cropland, nitrogen fertilizer (Nr) and water use and greenhouse gas (GHG) emissions exist, and could improve public health. We develop a new methodology for identifying nutritional constraints whose satisfaction by plant eaters is challenging, disproportionately shaping the optimal diets, singling out energy, mass, monounsaturated fatty acids, vitamins B3,12 and D, choline, zinc, and selenium. By replacing meat with the devised plant alternatives-dominated by soy, green pepper, squash, buckwheat, and asparagus-Americans can collectively eliminate pastureland use while saving 35-50% of their diet related needs for cropland, Nr, and GHG emission, but increase their diet related irrigation needs by 15%. While widely replacing meat with plants is logistically and culturally challenging, few competing options offer comparable multidimensional resource use reduction.

The opportunity cost of animal based diets exceeds all food losses.

Food loss is widely recognized as undermining food security and environmental sustainability. However, consumption of resource-intensive food items instead of more efficient, equally nutritious alternatives can also be considered as an effective food loss. Here we define and quantify these opportunity food losses as the food loss associated with consuming resource-intensive animal-based items instead of plant-based alternatives which are nutritionally comparable, e.g., in terms of protein content. We consider replacements that minimize cropland use for each of the main US animal-based food categories. We find that although the characteristic conventional retail-to-consumer food losses are ≈30% for plant and animal products, the opportunity food losses of beef, pork, dairy, poultry, and eggs are 96%, 90%, 75%, 50%, and 40%, respectively. This arises because plant-based replacement diets can produce 20-fold and twofold more nutritionally similar food per cropland than beef and eggs, the most and least resource-intensive animal categories, respectively. Although conventional and opportunity food losses are both targets for improvement, the high opportunity food losses highlight the large potential savings beyond conventionally defined food losses. Concurrently replacing all animal-based items in the US diet with plant-based alternatives will add enough food to feed, in full, 350 million additional people, well above the expected benefits of eliminating all supply chain food waste. These results highlight the importance of dietary shifts to improving food availability and security.

A model for 'sustainable' US beef production.

Food production dominates land, water and fertilizer use and is a greenhouse gas source. In the United States, beef production is the main agricultural resource user overall, as well as per kcal or g of protein. Here, we offer a possible, non-unique, definition of 'sustainable' beef as that subsisting exclusively on grass and by-products, and quantify its expected US production as a function of pastureland use. Assuming today's pastureland characteristics, all of the pastureland that US beef currently use can sustainably deliver ≈45% of current production. Rewilding this pastureland's less productive half (≈135 million ha) can still deliver ≈43% of current beef production. In all considered scenarios, the ≈32 million ha of high-quality cropland that beef currently use are reallocated for plant-based food production. These plant items deliver 2- to 20-fold more calories and protein than the replaced beef and increase the delivery of protective nutrients, but deliver no B12. Increased deployment of rapid rotational grazing or grassland multi-purposing may increase beef production capacity.

Expanded view of ecosystem stability: A grazed grassland case study.

Analysis of stability under linearized dynamics is central to ecology. We highlight two key limitations of the widely used traditional analysis. First, we note that while stability at fixed points is often the focus, ecological systems may spend less time near fixed points, and more time responding to stochastic environmental forcing by exhibiting wide zero-mean fluctuations about those states. If non-steady, uniquely precarious states along the nonlinear flow are analyzed instead of fixed points, transient growth is possible and indeed common for ecosystems with stable attractive fixed points. Second, we show that in either steady or non-steady states, eigenvalue based analysis can misleadingly suggest stability while eigenvector geometry arising from the non-self-adjointness of the linearized operator can yield large finite-time instabilities. We offer a simple alternative to eigenvalue based stability analysis that naturally and straightforwardly overcome these limitations.

Environmentally Optimal, Nutritionally Aware Beef Replacement Plant-Based Diets.

Livestock farming incurs large and varied environmental burdens, dominated by beef. Replacing beef with resource efficient alternatives is thus potentially beneficial, but may conflict with nutritional considerations. Here we show that protein-equivalent plant based alternatives to the beef portion of the mean American diet are readily devisible, and offer mostly improved nutritional profile considering the full lipid profile, key vitamins, minerals, and micronutrients. We then show that replacement diets require on average only 10% of land, 4% of greenhouse gas (GHG) emissions, and 6% of reactive nitrogen (Nr) compared to what the replaced beef diet requires. Applied to 320 million Americans, the beef-to-plant shift can save 91 million cropland acres (and 770 million rangeland acres), 278 million metric ton CO2e, and 3.7 million metric ton Nr annually. These nationwide savings are 27%, 4%, and 32% of the respective national environmental burdens.

Land, irrigation water, greenhouse gas, and reactive nitrogen burdens of meat, eggs, and dairy production in the United States.

Livestock production impacts air and water quality, ocean health, and greenhouse gas (GHG) emissions on regional to global scales and it is the largest use of land globally. Quantifying the environmental impacts of the various livestock categories, mostly arising from feed production, is thus a grand challenge of sustainability science. Here, we quantify land, irrigation water, and reactive nitrogen (Nr) impacts due to feed production, and recast published full life cycle GHG emission estimates, for each of the major animal-based categories in the US diet. Our calculations reveal that the environmental costs per consumed calorie of dairy, poultry, pork, and eggs are mutually comparable (to within a factor of 2), but strikingly lower than the impacts of beef. Beef production requires 28, 11, 5, and 6 times more land, irrigation water, GHG, and Nr, respectively, than the average of the other livestock categories. Preliminary analysis of three staple plant foods shows two- to sixfold lower land, GHG, and Nr requirements than those of the nonbeef animal-derived calories, whereas irrigation requirements are comparable. Our analysis is based on the best data currently available, but follow-up studies are necessary to improve parameter estimates and fill remaining knowledge gaps. Data imperfections notwithstanding, the key conclusion--that beef production demands about 1 order of magnitude more resources than alternative livestock categories--is robust under existing uncertainties. The study thus elucidates the multiple environmental benefits of potential, easy-to-implement dietary changes, and highlights the uniquely high resource demands of beef.

A geophysical foundation for alternative farm policy.

An optimization method could aid agricultural decision making by balancing societal desire(s) with resource management.

Urban paediatric trauma due to stab wounds: an Israeli hospital experience.

OBJECTIVE: To assess the incidence and types of stab wounds to hospitalized children and adolescents. SUBJECTS: The sample consisted of patients, age 6-18 years, who were admitted to our hospital with sustained injury between 1991 and 2007. RESULTS: In total, 83 patients were admitted as a result of penetrating (n = 51) and superficial (n = 32) injuries. Eighty-two were hospitalized, and one was declared dead upon arrival. Only 11 patients were hospitalized during the 1991-2000 period, and 71 during the 2001-2007 period. Ten patients were admitted to the intensive care unit (ICU); 23 patients were operated (hospital mortality = 0). Evacuation time (time from injury to hospital) was 10 min (mean time; maximum 35 min). CONCLUSION: This study found higher rates of hospitalization compared with those over a decade ago. These rates reflect not only changes in hospitalization trends and/or population growth in the hospital area but also an increase of urban violence. Israeli hospitalization system deals with paediatric trauma effectively, being well trained because of permanent terrorist activity.

Geophysics and nutritional science: toward a novel, unified paradigm.

This article discusses a few basic geophysical processes, which collectively indicate that several nutritionally adverse elements of current Western diets also yield environmentally harmful food consumption patterns. We address oceanic dead zones, which are at the confluence of oceanography, aquatic chemistry, and agronomy and which are a clear environmental problem, and agriculture's effects on the surface heat budget. These exemplify the unknown, complex, and sometimes unexpected large-scale environmental effects of agriculture. We delineate the significant alignment in purpose between nutritional and environmental sciences. We identify red meat, and to a lesser extent the broader animal-based portion of the diet, as having the greatest environmental effect, with clear nutritional parallels.

Adaptations to climate in candidate genes for common metabolic disorders.

Evolutionary pressures due to variation in climate play an important role in shaping phenotypic variation among and within species and have been shown to influence variation in phenotypes such as body shape and size among humans. Genes involved in energy metabolism are likely to be central to heat and cold tolerance. To test the hypothesis that climate shaped variation in metabolism genes in humans, we used a bioinformatics approach based on network theory to select 82 candidate genes for common metabolic disorders. We genotyped 873 tag SNPs in these genes in 54 worldwide populations (including the 52 in the Human Genome Diversity Project panel) and found correlations with climate variables using rank correlation analysis and a newly developed method termed Bayesian geographic analysis. In addition, we genotyped 210 carefully matched control SNPs to provide an empirical null distribution for spatial patterns of allele frequency due to population history alone. For nearly all climate variables, we found an excess of genic SNPs in the tail of the distributions of the test statistics compared to the control SNPs, implying that metabolic genes as a group show signals of spatially varying selection. Among our strongest signals were several SNPs (e.g., LEPR R109K, FABP2 A54T) that had previously been associated with phenotypes directly related to cold tolerance. Since variation in climate may be correlated with other aspects of environmental variation, it is possible that some of the signals that we detected reflect selective pressures other than climate. Nevertheless, our results are consistent with the idea that climate has been an important selective pressure acting on candidate genes for common metabolic disorders.