Sustainable Food System Approaches to Improving Nutrition and Health
Gerald F. Combs, Jr.(1), Ross M. Welch(2), (3)and John M. Duxbury (3)
The health and well-being of every person depend on access to sustenance provided by food systems of varying complexity. Yet, these systems have evolved with little explicit attention to the quality of their nutrient outputs or to their overall abilities to support good health, and poor nutrition diminishes the quality of life for billions of people, particularly the poor in developing areas of the world. Therefore, we feel that, to offer the poor reasonable chances for healthier lives, it will be necessary to exploit the potentials of improved food systems. This will require changes in thinking about agriculture, health, and national development.
Impacts of Malnutrition in Today's World
Food and nutrition-related problems are national development issues. Malnutrition affects nearly half the world's population: some 840 million people do not have access to enough food to meet their basic needs; an estimated 2 billion people live at risk to diseases resulting from deficiencies of vitamin A, iodine, and iron - most of them are women and children living in less developed countries; and more than a third of the world's children fail to reach their physical and mental potentials because of inadequate diets. Malnutrition decreases worker productivity and increases morbidity and mortality rates; by potentiating infectious disease, it accounts for as much as half of all child deaths. All of these effects compromise the abilities of people to compete for their livelihoods, leading to continuing cycles of poverty among the disadvantaged (see Combs et al, 1996).
Malnutrition is also a consumer and a public health issue. Even the United States, with the world's most plentiful and safe food supply and its most complex food system, has prevalent diet-related health problems (REF2). Improper diet is recognized as contributing to at least five leading causes of death (heart disease, cancer, stroke, diabetes, athero-sclerosis). An estimated fifth of pre-menopausal American women is anemic due, in part, to poorly bioavailable dietary iron. Low intakes of calcium contribute to bone disease among women. Child growth retardation and deficiencies of vitamins A and C are prevalent among Hispanic and African Americans of lower socioeconomic status. Prevalences of overweight and obesity are increasing. These problems erode the quality of life and have substantial social and economic costs. Because the U.S. economy and global stability are also affected by food-related problems in other parts of the world, and because food security will be increasingly threatened by the expected addition of 2.5 billion people over the next 25 years, food, nutrition and health are also political and national security issues.
Linking Human Nutrition Needs to Food Systems
The traditional approaches to addressing human food and nutrition needs have been through programs targeted either to increasing the production of staple foods or to correcting specific nutrient deficiency diseases. These approaches have been conceived along either agricultural or medical lines with relatively narrow focus and limited objectives. Such sectoral approaches tend to deal inadequately with truly complex issues; thus, most have not proven sustainable.
The best known agricultural approach to combating malnutrition was the "Green Revolution". That effort, implemented through the coordinated efforts of the Consultative Group for International Agricultural Research and various national agricultural research organizations, developed technologies that allowed many developing nations to realize impressive gains in the production of staple grains (rice, wheat, and maize). Its results were dramatic: rice and wheat production in South Asia increased by 200% and 400%, respectively, within three decades; the daily global availability of food energy per capita rose to about 2720 kcal, i.e., some 16% above minimum needs (REF3). But the current adequacy of global food production serious maldistribution problems notwithstanding, should not be cause for comfort. The world population, now numbering 5.9 billion, is growing at an estimated annual rate of 1.7% and is expected to double within the next 40 years. To meet the demands of this growth, further large increases in agricultural production must occur.
Despite its successes, the green revolution served to reduce agricultural diversity with unfortunate health outcomes. With favorable economic returns, farmers in the best agricultural environments rapidly adopted green revolution technologies and, over time, the new, relatively simple, cropping systems displaced more diverse traditional ones that, despite their lower calorie-protein outputs, provided foods with higher contents of essential micronutrients (vitamins and minerals)(4). Displacement of nutrient-rich traditional crops such as pulses (beans, peas, and lentils) has been exacerbated by the failure of plant breeders to produce high-yielding varieties of those crops. This can be seen in South Asia, where the production of pulses is now only 87% of what it was 30 years ago (REF4). The production of fruits and vegetables has also not kept pace with population growth. The result is lower availabilities and higher prices for micronutrient-rich foods - factors that limit their accessibility, particularly to low-income families.
The nutritional impacts of reduced agricultural diversity are clear: the availability of food iron in South Asia dropped from 6.2 mg/kcal in 1970 to 5.7 mg/kcal in 1988, while the incidence of anemia among pre-menopausal women increased from about 57% in 1977 to over 73% in 1987 (REF5). In fact, the incidence of anemia among South Asian women is 1.6 times greater than that among sub-Saharan African women, who, despite their higher prevalence of calorie-protein insufficiency, have greater access to dietary iron (REF6). This phenomenon is seen on a global scale; the prevalence of anemia (5) among all women has risen from 30% in 1980 to over 40% today (REF7). Therefore, while continued population growth makes it imperative to find ways to continue increasing agricultural production, focusing on staple food crop production alone is likely to increase micronutrient malnutrition. While micronutrient deficiencies can be overcome by including in diets pulses or animal products, along with vegetables and fruits, the poor often depend almost exclusively on low-cost staples; for example, polished rice provides over 85% of food energy for people in Bangladesh (REF8). Solving these problems, therefore, will call for strategies that address issues of food nutrient bioavailability and balance.
Evidence is mounting that high-input, green revolution agricultural technologies may not be sustainable (REF9). To support their high yields, the green revolution varieties require irrigation and costly inputs of fertilizers, fuel, and pesticides. High yields, therefore, are not realized by subsistence farmers who cannot afford high inputs; the green revolution varieties offer selective advantages to larger-scale farming operations that can afford them.
While agriculture has seen malnutrition as an issue of food availability, much of the health community has treated malnutrition like a disease. Accordingly, interventions have generally followed medical models, focusing on the proximate and evident causes of malnutrition in treating symptoms and, therefore, targeting specific nutrients. Health-based, sectoral interventions have thus had limited long-term impacts. Most have relied on food processing and pharmaceutical technologies, such as the use of food fortificants and specific nutrient supplements. While many such efforts have been successful, at least initially, in developing countries they frequently have encountered insurmountable economic, political, social and logistical barriers, and their costs have made them dependent on international support.
An example of an unsustainable intervention program is Sri Lanka's Thriposha (triple nutrient) program which was designed to supply, free of charge to poor mothers and children, energy, protein and micronutrients in a pre-cooked, cereal-based food (REF10). Started in 1973, the program was administered through school systems and maternal-child clinics and became an important part of the country's public health effort; yet, it never reached its goals of providing nutrients to the truly needy, of promoting local production of indigenous foods and of introducing to local markets an inexpensive, protein-rich food. Instead, Thriposha was made exclusively from imported foods and, in some households, became consumed preferentially by men. Some families maintained their eligibility for the supplement by keeping their children underweight. Some mothers used the supplement as a food replacer, therefore, not increasing in the nutrient intakes of their children. Last year the Thriposha program was discontinued.
Clearly, better approaches are needed to meet the increasing nutritional demands of an expanding global population. We believe that a new agenda for food and agricultural development is needed, one for a "greener revolution" directed at increasing the production of nutritionally adequate food supplies in ways that protect biological, socioeconomic, and political environments and, thus, ensure sustainability. To accomplish this, we believe that both agriculture and nutrition must be viewed in the larger context of their inherent interrelationships. Therefore, we convened a highly diverse group of experts from many disciplines, sectors and countries to develop such a new agenda. That group did so on the basis of a Food System concept that held human health and well-being as explicit outcomes (Combs et al, 1996).
We believe that the Food System concept can facilitate the development of food-
based strategies for preventing malnutrition. The concept encompasses all activities relating to the production, acquisition and utilization of food; it holds food systems as varied, complex, multicomponent systems with multiple inputs (labor, capital, knowledge, seed stock, etc.) and multiple outcomes, including the health and well-being of people within such systems. It considers these activities within several subsystems: production (including land use and tenure; soil management; crop breeding, selection and management; livestock breeding and management; and harvesting), acquisition (including food processing, transportation, storage, packaging and marketing; household purchasing; and food use traditions, practices and distribution) and utilization (including food preparation, processing and cooking; household food decision-making; food preferences; and access to health care, sanitation, energy and knowledge). The model holds the health and well-being of individuals as outcomes of these complex, nested subsystems interacting to varying degrees within biophysical, social, economic, public health and policy environments. From this perspective malnutrition is seen as a food systems failure.
Developing Food Systems Approaches to Micronutrient Malnutrition
We believe that the development of sustainable solutions to malnutrition, in both developing and industrialized countries, can best be addressed using systems approaches that conceive of objectives in multidisciplinary terms and take comprehensive views of both ends and means. While, historically, the agricultural sector has measured its success in terms of production, food systems approaches would expand that view to include measures of impacts on human nutritional and health status. Food systems approaches would identify the root causes of malnutrition and look broadly at food systems in the development of sustainable solutions.
In order to realize the potentials of food systems to prevent malnutrition, it will be necessary to enunciate the values and foci that would direct such approaches. In addressing micronutrient malnutrition, we suggest that these values should include: increasing the physiologic utilization of nutrients with prevalent deficiencies (e.g., vitamin A, iron, iodine, zinc); increasing the efficiency of resource utilization for nutrient production; reaching high-risk population groups; and being sustainable from environmental, social, and economic perspectives. We also propose that food systems approaches be focused on the staple foods most important in diets of the poor: beans, cassava, rice, wheat, and maize. To this end, we see three approaches as most appropriate: increasing the production of micronutrients; reducing the losses of micronutrients; and increasing the physiological utilization of micronutrients.
Increasing micronutrient production. Wheat cultivars vary in their abilities to thrive on soils with poorly available iron and zinc; this suggests that it should be possible to overcome limitations imposed by low soil mineral availabilities widespread in many parts of the world by breeding for increased efficiency of mineral uptake (Graham and Welch, 1996). Zinc-enhancement of seed, achieved experimentally by foliar application of the element to wheat plants, has been found to increase the viability and vigor of next-generation seedlings (REF11). This suggests that the development of zinc- and/or iron-enriched genotypes may have important agronomic benefits (e.g., lower seeding rates, reduced fertilizer needs, increased disease resistance, increased water use efficiency, improved grain yield) in addition to enhanced micronutrient contents in the edible grain. Such linkages to economically important traits will be important if enhanced micronutrient contents are to be added to breeding strategies. For rice and wheat, which are milled, it will be necessary to determine whether breeding can improve endosperm mineral contents; this may be possible if ways can be found to control tissue-specific expression of genes for such compounds as phytoferritin and leghemoglobin. Loss of aleuronal minerals is not a concern for beans or for grains such as maize, unpolished rice and wheat that can be consumed without milling; the finding of a multiple aleurone layer gene in maize indicates the potential to increase micronutrient contents of at least some species. Plant breeding may also be able to increase the vitamin contents of staple foods (e.g., rice with significant pro-vitamin A carotenoid content); genetic engineering methods may offer opportunities to transfer genes for such traits across species (e.g., developing rice containing beta-carotene).
Micronutrient output also can be enhanced by diversifying food systems. This can be approached through nutrition education and social marketing to affect food-related behaviors and household resource deployment strategies; such efforts must be linked to measures to increase access to micronutrient-rich foods. Approaches necessarily will vary according to local circumstances; many will call for re-diversifying food systems through the introduction of micronutrient-rich crops into crop rotations. Approaches such as including early maturing legumes in rotations of rice or rice-wheat can increase the availability of pulses while also return to soils nutrients needed to reverse stagnating cereal productivity. Home gardening efforts emphasizing vegetables and fruits will continue to be important; however, to have positive impacts, they must address the constraints to food production in resource-poor areas: extremes in water availability and temperature, availability of planting materials, fertile soils, protection from livestock and demands on women's time.
Reducing micronutrient losses. Micronutrient losses from food systems can be reduced by finding effective means of using the iron- and zinc-containing cereal brans. Bran retention from wheat can be increased by producing higher extraction flours; the success of this approach depends on consumer acceptance of the coarser products. Promotion of unpolished rice or food uses of rice polishings will call for finding ways to stabilize the highly unsaturated lipids contained in the bran. Key to these efforts will be finding ways to optimize fuel use for such activities as cooking and parboiling. Gains in this area, to the extent that they reduce use of brans as fuel, can increase their availability for food use or for recycling either as soil amendments or through animals as feeds.
Increasing the physiologic utilization of micronutrients. Micronutrient utilization from plant foods can be increased by reducing, phytate, the nondigestible (for humans and monogastric livestock) complex of iron, zinc, phosphorus and calcium in plants. Recent evidence suggests that the possibility of breeding reduced-phytate soybeans (REF12), but because phytates are storage forms of minerals in seeds and grains, there are questions about the impacts of such reductions on seed vigor and crop productivity. A better approach may be to develop sources of phytases for use in food engineering and diet formulation. This can be done by germinating wheat, which activates the expression of endogenous phytases, prior to food use, or by processing grains in ways that facilitate their fermentation by phytase-containing fungi. Heat-resistant fungal phytases have also been cloned.
The enteric absorption of iron and zinc can be enhanced by ascorbic acid and promoter substances in meats. Ascorbic acid reduces ferric iron to the more absorbable ferrous form and stabilizes ferritin post-absorptively to enhance the bioavailabilities of both nonheme (plant) and heme (animal) forms of iron. The presence of meats in meals enhances the absorption of both iron and zinc; there is evidence that this effect may involve the sulfur-containing amino acids methionine and cysteine (REF13). Elucidation of the "meat factor" would allow the characteristic to be incorporated in formulated foods, to be considered in planning meals, and, perhaps, to be enhanced in staple food crops through plant breeding or genetic engineering.
Conclusions
We believe that institutional changes are needed to promote more effective transdisciplinary linkages between the agricultural and health sciences and to facilitate holistic views of agriculture, food, and development. Barriers created inadvertently by narrow disciplinary orientations must be lowered by developing programs that focus on problems and reward transdisciplinary collaboration. Nutrition, health, and sustainable development must be viewed as instrumental to each other and programs must reflect that vision. Sustainable development implies the sustaining of people; it cannot be achieved without a population that is better nourished and healthier, more vigorous and productive in all ways - not just for physical labor, but also for mental creativity, social collaboration and civic life. This view is captured in the food systems concept: people are both the means and the ends in the food systems perspective and their well-being should be the dominant motivating and evaluative criterion for any program. Therefore, we see improving nutrition through a variety of mutually compatible and reinforcing ways as essential for any development effort. This task calls for food systems approaches.
References
Combs, Jr., G.F., R.M. Welch, J.M. Duxbury, N.T. Uphoff and M.C. Nesheim (eds). 1996. Food-Based Approaches to Preventing Micronutrient Malnutrition: an International Research Agenda. Cornell University, Ithaca, N.Y..
Graham, R.D. and R.M. Welch. 1996. Breeding for staple food crops with high micronutrient density. Agriculture Strategies for Micronutrients Working Paper 3. International Food Policy Research Institute, Washington, D.C.
1. Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
2. U.S. Plant, Soil and Nutrition Laboratory, USDA, Cornell University, Ithaca, NY, 14853, USA
3. Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, NY, 14853, USA
4. Cereals provide relatively meager amounts of vitamins and essential minerals; these are found mostly in the bran and germ which are removed during milling to produce foods deficient in these nutrients.
5. Although anemia can have several causes, including physiological iron losses in women and iron losses due to bleeding caused by parasitism or enteric disease, low intakes of poorly available dietary iron from plant sources is a significant contributing factor. Indeed, the prevalence of low iron status is thought to be as much as twice that of anemia.