Food Systems-Based ApproachesAbstract
Advances in agricultural production have not been clearly linked to human nutrition and health needs; this situation has had costly consequences. In the less developed countries, impressive gains in food production have not alleviated prevalent deficiencies of vitamins and minerals, which now affect nearly half of the world's population. The "green revolution" averted problems of starvation and protein-energy malnutrition that once seemed eminent; but those efforts, which focused on the staple cereals and the energy and protein those foods provide, failed to address health problems related to deficiencies of vitamins and minerals, which are not abundant in cereals. At the same time, the industrialized countries have experienced increasing, diet-related health problems of a different sort: diseases related to food excess and nutrient imbalance. For example, in the US improper diet is related to at least five of the top ten causes of preventable death, costing the American economy an estimated 18% of the gross national product. Addressing diseases related to food access and nutrient balance, whether they be the deficiencies in poor countries or the excesses of affluent countries, will require a new way of thinking about agriculture: as an instrument for improving human health.
Introduction
Food plays important social, cultural and economic roles in society; nevertheless, food remains the (usually sole) source of nutrition. Therefore, nutritional status and, to a great extent, health, depend on access to, quality of and diversity in food. Perhaps it is the very personal nature of food use that allows these issues to be often overlooked amid efforts to enhance economies, alleviate poverty and improve public health; but, in fact, these are the very issues that connect food to health outcomes.
Several trends provide the context in which ways must be sought to improve the abilities of agriculture to support improved health and well-being:
In this context, efforts must address several issues in order to be successful in exploiting the potentials of agriculture for the improvement ofhuman health and well-being. Thus, a consideration of the roles of plants in human health and nutrition is properly cast in terms that address these issues.
Current Diet-Related Health Problems
Health and well-being depend on access to sustenance provided by food systems, i.e., the interrelated activities concerned with the production, processing, acquisition and utilization of foods. Food systems vary considerably across the world, and each has evolved with little explicit attention to the balance and quality of its nutrient outputs or to its overall ability to support good health.
Even the US, with the world's most plentiful and safe food supply and its most complex food system, has prevalent diet-related health problems. Improper diet is recognized as contributing to at least five leading causes of death (heart disease, cancer, stroke, diabetes, atherosclerosis) (1-3); a fifth of pre-menopausal American women are estimated to be anemic due, in part, to poorly bioavailable dietary iron; low intakes of calcium contribute to bone disease (e.g., osteoporosis) among women; deficiencies of vitamins A and C and childhood growth retardation are prevalent among Hispanic and African-Americans of lower socioeconomic status; and the incidences of overweight and obesity are increasing in the general population. These problems (see Table 1) erode the quality of life and have substantial social and economic costs(1), making them both consumer and public health issues.
Table 1. Diet-Related Health Problems in the US (1-3)
| problem | links to diet | people affected | impacts |
| anemia | insufficient bioavailable Fe | 20-28% of women; 10-21% children |
impaired work productivity, increased morbidity, poor growth |
| metabolic bone diseases | insufficient Ca; excess P; poor vitamin D status | 13 million fractures (200,000 of the hip)/yr | increased fracture risk (hip, spine, radius); lost mobility; high mortality |
| low birth weight (<2kg) | poor prenatal care, including nutrition | 7 million; 50% infant deaths | increased morbidity and mortality |
| growth retardation | poor general nutrition | 13-15% of children 0-5y in some subgroups | impaired physical development |
| overweight | excess caloric intake, e.g., fat | 26% of people 20-74 yrs | increased risk to heart disease, diabetes, gall bladder disease, some cancers, osteoarthritis |
| heart disease and stroke | excess saturated fat, cholesterol, excess sodium, low folate | 7 million cases (350,000 deaths/yr) | increased morbidity and mortality |
| cancer | excess fat, low intakes of complex carbohydrates | 346,000 deaths/ yr (20% of all deaths) | increased morbidity and mortality |
| non-insulin-dependent diabetes | excess caloric intakes, e.g., excess fat | 7 million cases | increased morbidity and mortality |
Food, nutrition and health are also national development issues. Malnutrition affects some 40% of the world's people, particularly the poor in developing nations (4-7) (Table 2). Some 840 million people do not have enough food to meet their basic needs, and more than a third of the world's children are stunted due to inadequate diets. Nearly 2 billion people live at risk to diseases resulting from deficiencies of vitamin A, iodine and iron; most of them are women and children. By potentiating infectious disease, malnutrition is thought to account for half of all child deaths. Due to inadequate diets, a third of the world's children fail to reach their physical and mental potentials and many are made vulnerable to infectious diseases that account for half of all child deaths. Nutritional deficiencies decrease worker productivity and increase the rates of disease and death in adults. Many of these problems involve diets that provide insufficient amounts of vitamin A, iron, iodine, zinc, selenium and calcium. For the first time in many countries, these problems of under-nutrition are increasingly seen along side of problems of over-nutrition, traditionally the province of the industrialized countries (8). This situation, often called the "nutrition transition" seems to relate to recent increases in the global availability of cheap vegetable oils and the consequent increases in fat consumption by low-income families. This has meant that the nutrition transition now occurs at much lower levels of economic development that previously seen.
These problems persist in a world that now appears to produce enough total food to meet its current energy and protein needs (9-10). Indeed, impressive gains have been realized in global food production through the international agricultural research effort referred to as the "green revolution". But the, high-yielding, green revolution varieties of staple grains appear to have displaced traditional, more micronutrient-dense crops (e.g., pulses), thus, decreasing the diversity of many cropping systems and probably contributing to micronutrient malnutrition. Clearly, better approaches are needed to meet the increasing demands of a world that expects to add nearly 2.5 billion people over the next 25 years. Because, in an internationalized environment, global stability can be affected by food-related problems in any part of the world, and because food security will be increasingly threatened by continued population growth, food, nutrition and health are also economic, political and national security issues.
Table 2. Diet-Related Health Problems in the Developing World (4-7)
| problem | links to diet* | people affected | impacts |
| insufficient food | calories, protein and all other nutrients | at least 840 million | lost work productivity, impaired physical and cognitive development; excess morbidity and mortality; social unrest |
low birth weight (<2 kg) |
insufficient bio-available Zn, Fe | 35% of children 0-5 yrs. | impaired physical development; excess morbidity and mortality |
| vitamin A deficiency | insufficient pro-vitamin A-rich foods | 250 million (14 M with xerophthalmia) | impaired cognitive development; excess morbidity and mortality |
| anemia | insufficient bio-available Fe | 2.1 billion (including 42% of all women) | lost work productivity; impaired cognitive development; excess morbidity |
| Goiter | Insufficient I and/or Se | 200 million cases (1.6 billion at risk) | Lost work productivity; excess stillbirths, abortions and infant deaths |
| Cretinism | Insufficient I and/or Se | 6 million births/yr | Severe neurological impairment |
| Cardiomyopathy | Insufficient Se | 400 million at risk | Lost work productivity; excess morbidity and mortality |
*Other deficiencies, notably those of energy, protein, calcium and at least some vitamins (e.g., vitamins A and C, riboflavin), also contribute to many of these and other less widespread problems of malnutrition.
Need for a New Approach
The persistence of diet-related health problems is clear evidence that the traditional approaches to dealing with them have had limited success. The failures of food systems consistently to support good health can be attributed, in part, to their many complexities and interactions that ultimately affect nutrition and health outcomes. However, the constituent elements of food systems have generally been addressed only in isolation from each other rather than as parts of integrated systems. Accordingly, the scientific support base for these activities has been constructed largely along disciplinary lines, and research, training and outreach activities relating to food systems have been developed and deployed in separate and largely non-interacting programs. In the US, most of these activities, particularly those involving production agricultural research and outreach education, have been implemented through partnerships between the federal and state governments and the Land Grant Universities. While these partnerships have clearly led to remarkable gains in agricultural production, those gains have not been fully translated into improved health.
A new paradigm is needed to achieve that goal. Developing sustainable solutions to diet-related health problems is beyond the capabilities of individual disciplines or sectors. This task calls for trans-disciplinary and trans-sectoral efforts that address food systems in holistic ways, i.e., from the production, acquisition and utilization of foods to the bio-physical, economic, social, public health and policy environments in which those activities are carried out. Human health and well-being must be viewed as explicit outcomes of food systems. Such a view would constitute a new paradigm, expanding the tradition view of agriculture to include the promotion of human health. When made an institutional value, this new paradigm would facilitate the development of more effective trans-disciplinary research, outreach and instructional approaches to the complex and costly diet-related health problems of society while making agriculture a consumer issue.
Thinking in Terms of Food Systems
Such efforts can be facilitated by more clearly conceptualizing the Food System. Sobal et al (11) have offered a very useful conceptual Food System model which is similar in many ways to the informal representation of a recent international workshop (4). This model considers food systems as encompassing all activities relating to the production, acquisition and utilization of food. It accepts that Food Systems are varied, complex, integrated, multi-component systems with multiple inputs (e.g., labor, capital, knowledge, seed stock, etc.) and multiple outcomes, including the health and well-being of the people within such systems. The model includes sub-systems that can be described somewhat vectorially (Table 3), proceeding from the physical activities of the growing of plants and animals to the physiologic utilization by individuals of the nutrients provided by those foods. In fact, these are highly interrelated activities that occur within a variety of contexts (Fig. 1).
Table 3. Main components of the Food System model (after refs. 4, 11)
| Component | Subsumed Activities |
| Resource Inputs | materials, energy, human and economic capital, knowledge, etc. |
Food Production ("Producer") Sub-system |
activities related to the production, processing, transportation and marketing of food |
Food Acquisition ("Consumer") Sub-system |
activities related to the acquisition, preparation and consumption of food |
Food Utilization ("Nutrition") Sub-system |
physiologic utilization activities including ingestion, digestion, absorption, transport, metabolism, excretion, etc., of food nutrients |
| Health and Well-Being Outcomes | human health and welfare in the broadest sense, including not only freedom from illness, but also physical and emotional well-being |
| System Contexts | biophysical and social environments |
The Food Systems Model makes it fairly clear that the development of effective and sustainable solutions to diet-related health problems (in both the industrialized and developing world) will be best addressed using approaches that consider all relevant causal variables and conceive of objectives in multi-disciplinary terms. Such systems approaches contrast to the traditional approaches to agricultural, food and nutrition, which have generally been sectoral ones tending to address problems with relatively narrow focus and to define objectives in limited ways. Systems approaches address complex, real-world situations by considering effects across sets of variables and calling for dynamic modeling with the expectation that many effects will be non-linear and discontinuous. Because systems approaches take comprehensive views of both ends and means, they have particular value in addressing diet-related health problems. While, historically, the agricultural sector has measured its success in terms of production, systems approaches expand that view to include measure of impacts on human nutritional status. They do this by setting among the explicit objectives of an agricultural system that of producing healthy people and, to that end, that of producing foods of sufficient quality and quantify to support human health and well being. Whereas health-based sectoral approaches have traditionally focused on the proximate and evident causes of poor nutrition in treating symptoms, systems approaches seek to identify the root causes of poor nutrition and look broadly to Food Systems in the development of sustainable solutions.
Food Systems-Based Approaches
Approaches based on the food systems concept would demand that human food and nutrition needs be better linked to systems of food production and acquisition. This will require going beyond efforts that target only crop yields, to link those outcomes with improvements in consumer accessibility and nutrient content and bioavailability.
In designing further agricultural expansion, it must be remembered that past gains in agricultural production have not been without costs. The high-yielding varieties of cereals require infrastructure for irrigation and costly inputs in the form of fertilizers, fuel and pesticides to realize their high yield potentials. Evidence is mounting that these high-input technologies may not be sustainable. As practiced in resource-poor countries, they have decreased soil quality, reduced the diversity of crop production and contributed to environmental vitiation from the improper use of agricultural chemicals. Even in the US, a fifth of irrigated lands are estimated to be drawing down water tables. Food system-based approaches would, therefore, have strategies to reverse these trends.
For these reasons, food systems-based approaches must not be focused only on major crops; instead, they should consider entire cropping systems and their abilities to support balanced human nutrition in sustainable ways. This means going beyond the cereals, even though these crops will continue to be critical sources of food energy and protein. Cereals, however, provide only meager amounts of most vitamins and essential trace elements, and their small amounts of these micronutrients are found mostly in the aleurone layer cells associated with the bran and germ, which are removed during milling. Therefore, cereal-based foods (e.g., wheat flour, polished rice) tend to be low in micronutrients (12) (Table 4). Deficient trace element yields of cropping systems can be overcome, however, by including pulses (grain legumes such as beans, peas, and lentils) and/or animal products along with vegetables and fruits all of which are richer in micronutrients (13).
Food systems-based approaches would, therefore, emphasize the diversification of cropping systems. They would address the increasing needs for total food and balanced nutrient output simultaneously, and would do so in the context of environmental, economic and social sustainability. Food systems-based approaches would develop cropping systems that are optimized for the available physical resources of poor areas and that are sustainable in every sense of the word - food systems must be sustainable economically, but also environmentally and socially. Such systems must produce balanced nutrient output at least at region levels while striving to achieve as much balance as possible locally. This will require a new approach to agriculture - one that measures its success not only in bushels per acre yields or dollars per year, but also in terms of human health and overall sustainability.
Food Systems-Based Approaches in the Industrialized World
Hess (14) outlined food systems-based approaches would address health needs in sophisticated food systems such as those of the United States. His analysis highlighted needs for further improvements in food safety; the exploitation of health-protecting components of foods; reductions of food components that contribute to ill health; and envisioning nutrition research and education as investments to reduce health care costs, improve the quality of American life, and increase the international competitiveness of American agricultural products. When considered from the prospective of plant foods, the following opportunities would appear most promising:
These beneficial health effects have been outside the implicit bounds of traditional nutrition thinking, at least in the west. Thus, it has been necessary to expand our views of the diet-health linkage, as evidenced by the coinage of such terms as "phytochemical", "phytopharmaceutical", "nutraceutical" and "functional food" that are now used to describe these and other non-nutrient food components with disease-protecting effects. Improved technology will facilitate the detection, isolation and identification of food components with specific health benefits; and new tools of molecular biology and marker-assisted plant breeding combined with innovative crop management will make it possible to enhance these sorts of beneficial factors in the edible tissues of plants. For example, the Se contents of plant tissues can be increased by fertilization with sodium selenate, the use of Se-accumulating cultivars, and the exploitation of Se-rich soils for specialty crop production. Foods can be enriched with Se by using Se-rich ingredients in their formulation. With genetic engineering techniques it may even be possible to develop plant foods with high natural levels of specific anti-carcinogenic Se-metabolites as well as other micronutrients and beneficial factors include those derived from non-plant sources (e.g., the anti-tumorigenic polysaccharide lentinan from edible mushrooms [34] , the powerful anti-carcinogen conjugated linoleic acid from dairy products [35], and the unidentified factors in meats that enhance iron absorption).
Food Systems-Based Approaches in the Developing World - a "Greener Revolution"
The core strategies for a new international effort in food systems-based agricultural research (a "greener revolution") were laid out by an international expert consensus conference in 1995 (4). That group called for both biological and social science research to address several outstanding needs: better understandings of household decision-making related to food habits, agricultural practices, labor allocation and child care; simple, robust techniques for assessing the biological efficacies of trace elements from mixed diets; trace element contents of local foods in common database formats; creative new modalities by which the active participation of affected people (those operating within local food systems) can occur. Eliminating the serious micronutrient deficiencies of the developing world will call for food systems-based approaches that go beyond their diagnosis and description to deal seriously with their root causes. This can be achieved in several ways:
In addition to such programs, further efforts will be needed to utilize the emerging knowledge of nutrient and phytochemical effects in reducing risks to chronic diseases, which are also problems in poor countries. These efforts will call for food systems-based approaches such as:
Conclusion
Sustainable solutions to diet-related health problems can be achieved; but this will call for thinking about agriculture as more than an economic enterprise. The food systems perspective will be useful to this end, as it helps make clear the fact that human health problems, whether they be seen as chronic disease (e.g., obesity, diabetes, cardiovascular disease, cancer) or malnutrition (e.g., anemia, stunting, wasting, xerophthalmia, goiter, creatinism, rickets), are influenced not only by diet, but also by heredity and lifestyle in ways that are affected by many socio-economic, cultural and environmental factors. Food systems perspectives on these problems will take comprehensive views of food production in many contexts. This will call for a new view of agriculture: as an enterprise inextricably linked to human health, with its output properly measured not only in terms of quantity but also in terms of human health and welfare.
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1. Cardiovascular disease and cancer are estimated to cost the US over $200 billion annually; all diet-related illnesses are estimated to cost the US nearly a fifth of its GNP (1-3).
2. In 1995, the U.S. nutraceutical market was estimated to be as great as $17 billion (15).