Environmental Nutrition: A New Frontier for Public Health

Abstract

Food systems must operate within environmental constraints to avoid disastrous consequences for the biosphere. Such constraints must also take into account nutritional quality and health outcomes.

Given the intrinsic relationships between the environmental sciences and nutritional sciences, it is imperative that public health embraces environmental nutrition as the new frontier of research and practice and begins a concerted focus on the new discipline of environmental nutrition, which seeks to comprehensively address the sustainability of food systems.

We provide an overview to justify our proposition, outline a research and practice agenda for environmental nutrition, and explore how the complex relationships within food systems that affect public health could be better understood through the environmental nutrition model.

Balancing the requirements of food supply, health, and the physical environment—the health–environment–diet trilemma¹—is of great environmental and public health importance and will require new priorities for public health. We are now confronted with the challenge of adequately feeding a growing world population, which is expected to increase by around 2 billion people by 2050,² while maintaining environmental conditions that can sustain all life forms.³ The significant detrimental impacts of human activities on Earth’s ecosystems in the “Anthropocene” era have substantial implications for public health.^4,5 Prior to the Anthropocene era, relatively stable environmental conditions, including temperatures, freshwater availability, and biochemical flows, enabled the development of many and varied cultures for millennia.⁶ However, since the 19th century, when the Industrial Revolution was extended, human actions have had a significant impact on Earth’s environment on a global scale. Among other factors, a growing reliance on fossil fuels together with changes in food consumption habits and agricultural norms have brought us to the point of almost exceeding Earth’s biophysical capacity—that is, what the planet can sustain in terms of resource provision and absorption of wastes. A multinational team of scientists concluded that more than 1 boundary needed to maintain equilibrium of the planet’s biophysical processes has been transgressed.⁶ Of the 9 boundaries defined, the safe operating space has been exceeded for biodiversity, land system change, biochemical flows (the phosphorus and nitrogen cycles), and climate change.⁷ A consensus exists that rapid climate change is not only real but is occurring faster than previously thought.⁸ Global food provisions are expected to be widely affected by climate change,⁹ further threatening food security, which is already an escalating global concern.¹⁰ There is a high level of confidence among leading scientists that climate change is already adversely affecting crop production in several regions of the world. For example, since 2007 there have been several periods of rapid price increase for cereals and other foods, following extreme climate conditions in key producing regions.¹¹

The link between diet, health, and environment is well established.^12,13 An integration of the earth and life sciences with nutrition science must begin. It is essential that the protection of Earth’s resources and their interdependencies become a factor in the advancement of nutrition.¹⁴ We explore why, as a priority, the public health remit should expand to encompass the (physical) environmental and ethical dimensions of food systems.^10,15–17 The proposition to formally include environmental nutrition within the public health remit goes beyond the scope of current discussions on sustainable diets^14,18–20 to systematically consider the complex relationships within food systems that affect public health at a local and global scale, such as toxic contaminants, biological agents, and climate change. We also explore how the inclusion of such parameters could be executed to necessarily incorporate a complete understanding of food systems, through the environmental nutrition model.

THE EVOLUTION OF FOOD SYSTEMS

From a rudimentary perspective, food systems comprise the interaction of 4 main facets—resource inputs, drivers of demand, food outputs, and waste emissions, as depicted in Figure 1. Historically, the production of food was based on inputs of solar energy and of rain and surface water, and it featured multicrop enterprises that simultaneously raised plants and animals and utilized animal waste as fertilizer. It had relatively few detrimental impacts on the physical environment, partly because of population size and production techniques. Plants obtained nutrients from the soil and energy from the sun. Animals obtained nutrients and energy by eating plants, other animals, or both. Manure, crop rotation, polycultures, and routinely abandoning fields and allowing them to be taken over gradually by natural vegetation were the main sources of maintaining soil vitality. Agriculture evolved in very specific ecological settings that facilitated the domestication and selection of 4 main crops: wheat, rice, corn, and potatoes; these became the key foods to support the expansion of human populations.¹⁵

FIGURE 1—

Basic Model of a Food System

Although instances of intensive agriculture have existed for thousands of years, agriculture largely became industrialized over the past 2 centuries, which was inevitable under the dominant ideologies of political power and economic growth that founded the Industrial Revolution.²¹ In addition to the manufacture of synthetic fertilizers, the use of vitamins and antibiotics allowed more intensive types of agriculture, including animal farming, to become dominant. Globally, agricultural production doubled 4 times between 1820 and 1975.²² Monocultures replaced polycultures as the main crop production model. The Green Revolution saw the development of disease-resistant high-yield grain varieties and the implementation of irrigation, further increasing the intensity of food production. Despite a doubling of population over the past 4 decades, the Green Revolution has enabled agriculture to meet the world’s food needs.²³ However, intensifying the production of food has adversely affected biodiversity^3,24–26—which is declining at a global level and under continued threat^6,27—and human health through exposure to antimicrobial agents such as antibiotics,²⁸ biological agents such as viruses, and toxic chemicals such as some pesticides.²⁹

The global food system now has enormous adverse impacts on the physical environment. Since the Industrial Revolution, the food system has become much more complex, with an increased range of inputs, drivers, outputs, and waste emissions (Figure A, available as a supplement to the online version of this article at http://www.ajph.org). Prevailing political, economic, and cultural governing structures influence the characteristics of inputs, drivers, outputs, and waste emissions, and also how these key aspects relate to each other. The life cycle of food types has expanded to include new stages such as manufacturing, packaging, long-distance transportation, storage, and waste. Consequently, the environmental costs of food production are now substantial, including the degradation of inland waterways, nitrogen and phosphorus pollution of coastal marine ecosystems leading to “dead zones,” the development of photochemical smog, and rising global concentrations of nitrous oxide and methane, which are both greenhouse gases (GHGs) contributing to the process of climate change.^30,31 Vast amounts of oil and gas are used to provide raw materials and energy for the manufacture of fertilizers and pesticides and throughout all stages of food production, from planting, irrigation, feeding, and harvesting to processing, cold storage, distribution, and packaging. In addition, fossil fuels are essential in the construction and repair of equipment and infrastructure needed to facilitate this industry, including farm machinery, processing facilities, storage, transportation, and roads.³² Hence, the current food system is one of the biggest consumers of fossil fuels and one of the largest emitters of GHGs.^3,9,33

Wastage, including food loss, is also a major issue in current food systems. Analyses of the US food system have shown that avoidable food waste accounts for between 29% and 40% of annual production.^34,35 At a global level, it is estimated that one third of all food produced for human consumption is lost or wasted,³⁶ with much more of this occurring in the industrialized world than in developing countries.³⁷

Demand for food is largely defined by the technology, social structure (including cultural norms), availability of certain foods, and food policy in a given society. Societal demand and dietary choices are of fundamental importance in terms of the severity of environmental impacts.^18–20,38 Certain food groups have a much larger resource requirement and hence environmental footprint, with animal-based products generally having the greatest impacts and plant foods having the least.^39–43 This is important not only from a current perspective but also in consideration of the predicted increase in demand for animal products from emerging economies.⁴⁴ The environmentally hazardous aspects of animal production include the use of growth-promoting antibiotics and manure as a waste product.⁴⁵ Furthermore, it has been estimated that livestock production alone accounts for around 15% of global GHG emissions,⁴⁶ thus contributing significantly to climate change. The environmental impacts of such dietary choices in turn have significant public health implications—for example, air and water contamination from hazardous chemicals, animal waste, and zoonotic disease.^5,45 In addition, climate change is already having adverse human health consequences and is expected to have more,⁴⁷ including more deaths through temperature extremes, increased spread of infectious disease,⁴ reduced food yield in some regions, and increased threat to food security.^11,39

THREE DIMENSIONS OF NUTRITION SCIENCES

Currently, human nutrition covers 2 main aspects: individuals and communities. Although “public health” and “community” are not necessarily interchangeable, the use of “community” here purposefully allows differentiation of the existing and proposed aspects of public health nutrition. At its core, the discipline of nutrition is, and will remain, a biological science centered on biochemistry, physiology, and medicine. It is concerned with the interaction of food and other sources of nutrients and with the physiological, metabolic, and genomic systems of the human body. By extension, it addresses the effect of these aspects on health and disease⁴⁸ (see the box on the next page). Public health nutrition emerged in recognition of the importance of community welfare, including social, economic, political, and human aspects. Thus, nutrition extended its disciplinary scope to incorporate such concerns. This research expansion has had a tremendous impact on public policy, both nationally and internationally. Specifically, the public health nutrition agenda incorporates a range of social and multidisciplinary sciences—including epidemiology, anthropology, and sociology—to address nutritional deficiencies, disease epidemics, disease prevention, and food security (see the box on the next page).

Focus of Nutrition Dimensions

	Nutrition Dimensions
	Human Nutrition	Community Nutrition	Environmental Nutritiona
Scientific disciplines covered by each dimension	Biological sciences	Social and multidisciplinary sciences	Environmental sciences
	• Biochemical	• Epidemiology	• Physical
	• Physiological	• Anthropology	• Atmospheric
	• Medical	• Political science	• Ecology
		• Economics	• Geography
		• Sociology
	Scope of Dimensions
	Individuals	Communities	Biosphere
Issues addressed	Growth	Epidemics of chronic disease	Agricultural practices
	Adequate diets	Nutritional deficiencies	Sustainable food systems
	Nutrient requirements	Disease prevention	Societal demands and marketing
	Disease management	Food security	Benign food technologies
			Public policy

^aEnvironmental nutrition also covers disciplines covered by human and community nutrition.

As public health nutrition emerged from the science of nutrition for individuals, we are now on the forefront of a new expansion to incorporate environmental considerations (Figure B, available as a supplement to the online version of this article at http://www.ajph.org). The nutrition of individuals and communities can only be maintained within an environmentally sustainable context, which is currently under serious threat.⁶ Environmental nutrition seeks to address the sustainability of food systems by integrating the environmental sciences with the nutritional sciences, addressing a range of issues from production practices to societal demands on a biospheric scale (see the box on the next page). The existing multidisciplinary nature of public health nutrition lends itself to incorporating further disciplines. Given the intrinsic interrelationships between the environment and nutrition,²⁶ the current public health nutrition agenda must expand to embrace environmental nutrition as a new frontier.

THE ENVIRONMENTAL NUTRITION MODEL

Incorporating environmental nutrition into public health will necessitate a comprehensive understanding of food systems and their impact on the biosphere. In an effort to clarify the interaction between current food systems, the environment, and public health, we propose an environmental nutrition model (ENM). This model, portrayed in Figure 2, is intended to provide a useful didactic tool to explain, understand, and ultimately contribute to the necessary modifications and changes to the current food system to achieve sustainability. The ENM is a conceptual framework that encompasses the multifaceted physical and social dimensions of the food system and its unintended and undesired consequences on the biosphere, including public health impacts. Although this is relevant to all types of food systems, Westernized industrial food systems centrally controlled by governments or multinational conglomerates are the selected focus, given their growing dominance and influence on other food systems.

FIGURE 2—

The Environmental Nutrition Model, Including an Example of the Relationships Between Climate Change and Food Security

Through the ENM, the inputs and outputs related to the whole life cycle are considered and quantified for individual food items, which can then be used to assess and compare whole diets. The life cycle of food includes the production, processing, transportation, storage, retail, and consumption and disposal practices employed. For each food item, the ENM can produce a comparable list of inputs such as water, energy, land, and chemicals (including fertilizer and pesticide), and of outputs, including GHG emissions, manure, and waste throughout the entire life cycle. One of the aims of the ENM is to calculate a comprehensive range of environmental outputs and impacts; therefore, for certain food items, additional aspects must be considered. For example, for livestock products, respiration and manure can be factored into the life cycle assessment. Another important aspect to take into account is the missed opportunity for carbon sequestration in relation to land use and crop type.⁴² An assessment of the biodiversity impacts should also be included.²⁵

Societal demands would be considered in the ENM, including consumer preferences, policy, marketing, and social dynamics. The nutritional adequacy of each food item or dietary pattern would also be assessed, resulting in a comprehensive assessment of each food item or dietary pattern in terms of the environmental and public health impacts.

As depicted in Figure 2, there is a direct feedback between natural resource use and environmental pollution as the latter influences the former and vice versa. The types and quantities of resources used influence the type and amount of pollution created, which in turn compromises the quality of natural resources. The required output of the food system (i.e., food) serves and in turn influences societal demands and composes the dietary patterns of diverse populations. Diet-related health issues—including obesity, chronic disease, and malnourishment—are a major consequence of the food system. Food consumption patterns or consumer preferences can influence the extent of environmental degradation (as outlined in the section “The Evolution of Food Systems”). Policy can also significantly influence consumer demands—for example, by subsidizing the production of certain food types more than others, which in turn artificially lowers retail price and increases consumption. In addition, policy and governance are crucial factors for food sovereignty—for example, food systems can become largely controlled by a small number of corporations rather than by everyone involved, including consumers.⁴⁹

The environmental impacts of the food system can in turn influence nutritional outcomes. For example, GHGs are an output of the food system that contribute to climate change, which in turn affects food production through reduced yields and nutritional content.¹¹ These impacts subsequently increase malnutrition and food insecurity. Coupled with the global impacts of climate change which the food system significantly contributes to,⁹ malnutrition and food insecurity in turn raise issues related to environmental justice and intra- and intergenerational distributive justice.^10,16

As a specific example, to fully demonstrate the complex range of inputs and outputs of the food system, we provide a case study of beef. In the United States, the production of 1 kilogram of beef requires the input of 10 kilograms of grain feed,⁵⁰ more than 8000 liters of water, almost 8000 kilojoules of energy, 150 grams of fertilizer, 7 grams of pesticides,³⁸ and 21 square meters of land.⁵¹ Inputs on the demand side include marketing, cultural norms, technology, and such policies as government subsidies, either as direct payments to farmers or through public nutritional assistance programs, both of which increase availability to consumers. Governance issues can also be an important consideration; in the United States, for example, beef processing is largely controlled by 4 corporations. The environmental outputs of concern include solid, liquid, and air pollution (from animal manure, urine, blood, and hair; antibiotic residues; fossil fuel combustion; nitrogen and phosphorus), and GHGs (primarily methane, nitrous oxide, and carbon dioxide). Other outputs include nutrients for human consumption and contributions to chronic disease⁵² and infectious disease.⁵ Equity and food security issues are relevant, as producing livestock for human consumption is a very resource-inefficient process, with about an 89% loss of biomass through the life cycle.⁵⁰ Compared with producing 1 kilogram of protein from kidney beans, the production of 1 kilogram of protein from beef requires approximately 18 times more land, 10 times more water, 9 times more fuel, 12 times more fertilizer, and 10 times more pesticide.⁵¹ In addition, the United States uses 67% of total calorie production for livestock feed and could feed almost 3 times as many people per cropland hectare by shifting crop calories to direct human consumption.⁵³

ENVIRONMENTAL NUTRITION AGENDA

Expanding public health to include environmental nutrition will require dialogue and research in 4 overarching areas of the global food system: food production, food consumption, nutrition policy, and the integrated assessment of these areas.

So far, food production has attracted the most attention, much of which is focused on reducing the inputs required through technological means, rather than replacing less efficient food crops with more efficient ones.¹³ Hence, it is essential to identify resource-intensive commodities and those that could replace them, and also to assess the relative health implications. Although biodiversity loss ranks among the major drivers of ecosystem change, it remains a relatively neglected area of investigation.⁵⁴ Loss of biodiversity also has implications for public health, including an exacerbation of existing health inequities through exposure to environmental hazards or through loss of livelihoods.^49,55 Hence, biodiversity impacts must also be a strong consideration in food production.²⁴

To successfully feed a growing world population while protecting and remediating the environment, food consumption patterns must be considered and altered.^14,56 The potential level of control that consumers have over their purchases, particularly in developed nations, implies a level of elasticity in demand and hence a significant potential to modify the environmental impacts incurred within the food system and to alter personal health outcomes. The level of consumer control depends on many factors, including the amount of money they have available and their access to alternative foods. The key questions in this area are how, where, and when can the sustainability and nutritional quality of dietary choices be simultaneously optimized? So far, there is a lack a comprehensive analysis to address these issues.¹³

The main area requiring attention within policy research relates to the integration of policy options to address problems from a holistic perspective. For example, there is a need to assess how food production can be adjusted on a large scale to reduce environmental impacts and provide health-promoting foods while also accounting for the required changes in food consumption on the demand side. Essentially, policies need to be developed in a way that ensures that all of the stages from food production to postconsumption are coherent and cooperative with a global-health-promoting, environmental-conservancy agenda. This could involve a mixture of regulatory and fiscal measures.¹³ The latter, which have been explored to some extent, have been shown to reduce dietary GHG emissions.⁵⁷ However, there remains much to explore, particularly in relation to how societal demands can be adjusted to embrace healthy and sustainable foods, and how measures such as a restructuring of food subsidies could support such change.¹³

Given the interrelationships, it is essential to integrate food production, consumption, and other relevant aspects in a way that allows a comprehensive analysis of food systems. It is important to identify foods that are both sustainable and healthy and to develop a food-labeling scheme to communicate such information to consumers. Developing a set of sustainability and social indicators is likely to be important in assessing the scale and speed of the transition. Measures that increase the sustainability of food systems should be evaluated in terms of whether they require technological change for the producer or behavioral change for the consumer, and the type and level of policy intervention required to implement such measures.

To conduct comprehensive assessments of food systems, the development of an analytical tool is required. Such a tool would take into account the health, nutritional, and environmental aspects of food choices and allow for the exploration of additional factors such as policy scenarios, monetary costs for the consumer, and equity and cultural considerations.^12,58 One of the key components within such a tool is an environmental life cycle assessment of foods across the entire food system. The growing body of research in the life cycle assessment of food offers a useful insight into the current system of food delivery, which can be simple or complex. For example, the life cycle of a potato involves growing, harvesting, washing, packing, transporting to a distributor and then to a retailer, purchasing at a store, transporting to a home, cooking, and disposing of any waste. This is a fairly straightforward route compared with that of a tomato grown to produce ketchup. The process is more complex, and even more so if the ketchup becomes one of several food items in a ready meal—the route becomes staggering.

Currently, the focus of life cycle assessments is on the GHGs from dietary patterns. This must be expanded to incorporate a broad range of environmental aspects, including water use, energy use, chemical use (pesticide and fertilizer), land use, and waste products (including solid, gaseous, and effluent) from each aspect.¹² The focus on GHGs has partly arisen through a lack of sufficient information on other environmental aspects—for example, there is currently very little analysis of the impacts of global food wastage from an environmental perspective.³⁶ Hence, research efforts are also required to develop the data inputs that would facilitate the inclusion of such environmental impacts. In addition, regionally specific analyses must be developed to increase accuracy and applicability.¹² Most life cycle assessments currently focus on food production, so there is a need to expand the analysis to include other stages of the food system.⁵⁹

CONCLUSIONS

Paradoxically, although the current food system is reliant on the natural world, it is also a major contributor to its degradation. Food production, processing, transportation, storage, and packaging, coupled with an ever-increasing population and consumer demand, is using natural resources and producing waste at unsustainable rates. In turn, this results in serious implications for public health, including climate change, food insecurity, and changing food consumption patterns. The food system must operate within environmental constraints to avoid disastrous consequences for the biosphere. Given the intrinsic relationships between the environmental sciences and the nutritional sciences, it is imperative that public health research and practice begin a concerted focus on the new discipline of environmental nutrition, which seeks to comprehensively address the sustainability of food systems.