Feeding a Growing World Population
Toward a "Greener" Revolution
Two billion people suffer from terrible nutrition. We need to start producing not just more food, but more nutritious food.
Thanks in large part to the now-legendary green revolution, most people in the world today get enough calories from food for their subsistence. Yet it is becoming increasingly clear that the green revolution was not an overwhelming success. Although it helped increase the production of staple foods, it did so at the expense of overall nutritional adequacy. Today, large numbers of the world's people remain sick and weak because of terrible nutrition.
The green revolution increased the overall production of high-yielding rice, wheat, and maize, which provide most of the "macronutrients" people need in large quantities, notably carbohydrates and protein. But these foods do not provide the "micronutrients" needed in smaller quantities: iron, zinc, iodine, vitamin A, beta carotene, selenium, copper, and other compounds and essential elements that are just as critical to health. In addition, the increasing production of staples displaced the raising of local fruits, vegetables, and legumes that were the chief sources of micronutrients for most people.
As a result of this growing imbalance in food production, an insidious form of malnutrition plagues the world today. More than 2 billion people-about 40 percent of the world's population-now face debilitating diseases because their diets are dangerously low in precious micronutrients. Children's growth is stunted. Adults are weak and sickly, unable to resist disease and infection. This hidden hunger decreases worker productivity and increases morbidity rates, condemning people and their developing nations to vicious circles of ill health and low productivity, making it impossible to sustain economic growth. Low iron intake alone cripples efforts to improve primary school education-widely acknowledged as one the greatest levers to a nation's advancement-because the developing brain needs iron to learn.
Worldwide, iron deficiency leaves 40 percent of all women and 50 percent of pregnant women anemic and causes up to 40 percent of the half-million deaths in childbirth each year. More than 220 million children with diets deficient in vitamin A cannot maintain their immune systems or the lining of their respiratory tracts, succumbing easily to disease and infection. Severe vitamin A deficiency also blinds up to a half-million children each year, half of whom die within six months of losing their sight. Millions of poor people with diets low in iron and zinc cannot fight off malaria, diarrhea, and pneumonia, three of the world's leading killers.
Nutritional problems are serious in the United States, too. Four of the 10 leading causes of death here-coronary heart disease, cancer, stroke, and diabetes-are associated with diets too heavy in calories, fat, saturated fat, cholesterol, and sodium and too light in plant foods high in fiber and available micronutrients. Poor nutrition plays a central role in obesity, hypertension, and osteoporosis. Iron deficiency affects nearly 20 percent of all premenopausal women and 42 percent of all poor, pregnant African-American women. Folic acid inadequacy is increasing the risks of birth defects, heart disease, and stroke, and zinc deficiencies are affecting the immune function of the elderly and the size of infants born to poor black women, and even retarding the growth of upper-middle-income adolescents. According to the U.S. Department of Agriculture (USDA), these chronic diseases cost U.S. society an estimated $250 billion annually in medical expenses and lost productivity, of which $100 billion is directly associated with poor nutrition.
From a systems perspective, the food system is failing. Current U.S. and international policies and programs are to blame, and not changing them will have severe consequences for human health and welfare. This is not just a social responsibility; it also carries political liabilities. Malnutrition and poor health in countries overseas increase reliance on international aid. They also exacerbate social instability, leading to mass unrest and political tumult that jeopardizes U.S. international relations. A 1993 study by Jere Behrman at the University of Pennsylvania shows that investing in nutrition is one of the most economically efficient ways to strengthen market-based economies in developing nations, which would significantly benefit U.S. trade.
What the United States and the world need is a second food revolution-a greener revolution that will provide not just more food but more nutritious food, ending reliance on the extremely expensive and piecemeal distribution of supplements and food fortification programs that are now the mainstay of global nutrition policies. The failing food system can be fixed in four ways: by breeding crops that have higher micronutrient contents, increasing the diversity of food crops, reducing the losses of nutrients that occur with current harvesting and food production techniques, and changing the mix of foods eaten during meals in ways that promote better natural absorption of nutrients by the body. Pursuing these policies will require major changes in direction by domestic and international policymakers and research organizations.
Feeding the developing world has been addressed primarily by increasing the production of starchy staple foods (cereal grains) and correcting specific nutrient deficiencies that lead to disease. Programs to increase production have been implemented largely through the Consultative Group for International Agricultural Research (CGIAR) and various national agricultural research organizations. Thanks in large part to the tripling of fertilizer use, a one-third increase in the amount of irrigated land, and the development of high-yielding cereal varieties, many developing nations have realized impressive gains in the production of rice, wheat, and maize. The production of rice and wheat in South Asia, for example, increased by 200 percent and 400 percent, respectively, during the past three decades. The global availability of calories rose to its present estimated level of 2,720 kilocalories per person per day, which is about 16 percent above minimum needs, preventing famines in many countries.
But the focus on grains had an unintended and unfortunate consequence: It reduced the diversity of traditional cropping systems. Farmers adopted simpler rotations of the higher-yielding and more profitable grains and abandoned lower-calorie foods that were nonetheless generally higher in protein and micronutrients. Crops such as pulses (the peas, beans, and lentils from leguminous plants) were displaced. This trend was exacerbated by the failure of plant breeding to produce higher-yielding varieties of these micronutrient-rich crops and by policies, especially free water and guaranteed prices, that subsidize grain production. Today, the production of pulses in South Asia is only 87 percent of what it was 30 years ago. At the same time, the production of fruits and vegetables did not keep up with the needs of growing populations in eight South and Southeast Asian countries. Further damage to balanced diets came from mass milling and polishing of grains, which remove the bran and germ, the parts of the grain where the micronutrients are stored. Together, these effects have resulted in lower availabilities and higher prices for micronutrient-rich foods. This particularly hurts low-income families.
Various organizations, such as the UN Food and Agricultural Organization (FAO), the World Bank, CGIAR, the World Health Organization, UNICEF, and others commit hundreds of millions dollars annually to improving agricultural production, health care, and disease prevention by distributing supplements (such as vitamins) and fortifying foods during production. Current programs are cost effective. World Bank studies show that the productivity gained by a country due to a healthier population (per program dollar spent on vitamin A, iron, and iodine supplements and food fortifications) can result in a benefit-to-cost ratio ranging from 2:1 to as high as 260:1.
However, sustaining these kinds of programs is a problem. They require a great deal of oversight and logistical control. When budgets get cut, the distribution system breaks down and is often not subsequently fixed. Some countries don't add additives to foods correctly and some don't add the additives at all. Fortifying foods requires sophisticated food processing technology that many developing countries cannot afford. Finally, many of the programs do not provide nutrient balance because they focus on one or a few nutrients, neglecting the other essentials. It is simply more effective to breed, grow, harvest, and sell or distribute a better mix of more nutritious, locally available foods.
Yet the many organizations named above devote little or nothing to improving the actual nutrient content of crops. To make matters worse, national departments of agriculture and agricultural universities in developed countries concern themselves almost exclusively with improving the yield of crops but not the nutrition content and diversity of crops in cropping systems that are fundamental to improving even an advanced nation's health and well being.
Recently, Howarth Bouis at the International Food Policy Research Institute (IFPRI) in Washington, D.C., calculated the annual cost of an iron-fortification program in India and compared it to the spending that would be necessary for a more sustainable food systems approach: breeding iron-rich staple crops. The iron-fortification program would cost a minimum of $0.10 per person per year when all administrative costs were included. The annual cost to fortify food for only half of India's 880 million people would therefore be $44 million. Although such an expenditure is probably cost effective in terms of return on investment, it is still a large sum of money and would need to be justified and allocated each year by the Indian government. Bouis then calculated the cost of breeding iron-rich rice, wheat, beans, maize, and cassava. The research required to develop these staples over five years was estimated to cost about $2 million for each crop, totaling $10 million for the five crops, much less than the cost of just one year of food fortification. And the plant breeding strategy is a one-time expense and is transportable to other countries. The economics of plant breeding overwhelm the economics of supplementation or fortification.
Diverse foods are key
Adequate nutrition can best be provided by basing diets on a wide variety of foods, including pulses, animal products, vegetables, and fruits. The poor, however, are usually forced to depend almost exclusively on low-cost, high-energy, but low-nutrient starchy foods. Polished rice now provides 85 percent of the caloric intake in Bangladesh, and wheat flour provides nearly that percentage of calories for the poor in Pakistan. The decreasing production of micronutrient-rich foods has been identified in many parts of South Asia, China, sub-Saharan Africa, and South and Central America.
Although continued population growth makes it imperative to continue increasing total agricultural production, focusing only on caloric output will worsen micronutrient malnutrition. In parts of Ethiopia, malnutrition has persisted despite heavy investments in agricultural infrastructure that have produced significant increases in the production of staples. Egypt has increased staple food production by more than 600 percent in 30 years, yet problems of micronutrient malnutrition such as anemia and stunting actually appear to be growing. In Mexico and Kenya, iron, vitamin A, and iodine deficiencies continue to affect enormous numbers of people even though agricultural production is at an all-time high.
A large part of the reason we are losing ground is that the health community has treated malnutrition as it does disease: Find a single fix for a single symptom. Although supplement and fortification programs in developing countries often succeed initially, they soon encounter insurmountable economic, political, social, and logistical problems, and their costs make them dependent on international support.
A typical example is Sri Lanka's Thriposha (triple nutrient) program. It was designed to supply energy, protein, and micronutrients in a precooked cereal-based food free of charge to poor mothers and children. Started in 1973, the program was administered through school systems and clinics and became an important part of the country's nutrition policy. Yet its goals were never reached. Instead, Thriposha was eaten primarily by the men in households, and some families deliberately kept their children underweight in order to stay eligible for the program. Some mothers used the supplement as a food replacer, which often resulted in no net increase in nutrient intake by their children. Consequently, in 1995 the Sri Lanka Poverty Alleviation Project recommended that the program be discontinued.
The vitamin A supplement program in Indonesian has also fallen short. With extensive training and close supervision of highly motivated community health workers, the program achieved 77 percent coverage of children within its first two years. But after 15 years, the coverage has dropped to less than 50 percent, largely because government motivation and support have dwindled. In Bangladesh, the "universal" vitamin A supplement program reaches only an estimated 36 percent of the target population.
Clearly, better approaches are needed to meet the increasing nutritional demands of a world that expects to add at least 2.5 billion people during the next 25 years. A greener revolution directed at increasing the production of micronutrient-rich foods would ensure sustained improvements in health. To accomplish this task, agriculture and nutrition must be viewed in the larger context of the food system, which involves the production, distribution, and utilization of food. This requires a new mindset for the development of agricultural and food policies, in which the measure of success is not in terms of production but in terms of human nutrition and health. The principal objective of a food systems approach would not be to produce more food but to produce more healthy people.
Several food system programs are already achieving this measure. In the remote Xinjiang Province of China, table salt iodinization programs failed to reduce iodine deficiency diseases for a variety of cultural reasons. But when iodine was added to irrigation water, the iodine content of all irrigated foods and feedstuffs increased, improving the iodine health of the people as well as livestock. Iodine deficiency diseases were largely eliminated, improving community and family health and providing economic gains for farmers.
In Thailand, Bangladesh, and Zimbabwe, the availability of foods rich in beta carotene, a precursor to vitamin A, has been greatly increased through concerted efforts to popularize home gardening. These programs have increased the amounts of vegetables and fruits consumed at home and sold inexpensively at local markets frequented by low-income families. Meanwhile, researchers at the International Center for Tropical Agriculture in Cali, Columbia, have identified a strain of cassava, a staple in South and Central America and western Africa, that is high in beta carotene.
Other food system approaches are being tested. Half of all arable lands are regarded by scientists as deficient in iron and zinc, despite the fact that those soils contain ample amounts of both minerals. The problem is that the roots of today's high-yielding crops are poor at absorbing these minerals. In Turkey, where extensive zinc deficiency is causing stunting among children, current strains of wheat are unable to absorb the zinc that is tied up in the soils. In a NATO-sponsored research project, scientists are breeding high-yield varieties of wheat that can better utilize the zinc in the ground, with little or no use of zinc fertilizers. Early results are promising.
A similar strategy is being developed in a collaborative effort of IFPRI, the University of Adelaide, the International Rice Research Institute, the International Center for Tropical Agriculture, the International Center for Maize and Wheat Improvement, and USDA's Federal Plant, Soil, and Nutrition Laboratory at Cornell University. It will determine the potential for improving rice, wheat, corn, beans, and cassava as sources of iron, zinc, and pro-vitamin A carotenoids. The effort involves screening the world's collections of germ plasm for these crops to determine whether sufficient genetic diversity exists to breed more nutritious plants.
More nutritious food
Failing food systems can be fixed in four ways: by increasing the micronutrient content of crops, increasing the diversity of food crops, reducing the loss of nutrients that occurs in harvesting and food production techniques, and changing the mix of foods eaten during meals to promote better absorption of nutrients by the body. A good starting place would be to create a comprehensive database of the micronutrient composition of staples, vegetables, and fruits grown in regions around the world. A collaborative effort involving CGIAR and land-grant universities would bring together the expertise needed to accomplish this. These data could then be converted to "nutrient balance sheets" that policymakers could use to assess national food production plans.
Work to breed more nutritious plants should begin with increasing the nutrient content of the staples most important to the diets of the poor. The single greatest advance would be to breed new strains that take up and retain more of the essential minerals (particularly iron and zinc) from the soil. An alternative, mineral fertilizers, is an expense that poor farmers cannot afford and that does not work for iron.
New plant varieties would create an added payoff: Cereal grains with increased zinc, copper, and manganese density have more hearty seeds and are more resistant to plant disease and drought. They would raise farmers' yields, thus lessening required seeding rates, reducing the use of pesticides, and decreasing the amount of watering needed.
Breeding strategies need to improve rice and wheat in another way. The outer layers of cells in these grains are rich in micronutrients, but those layers are removed by milling and polishing; rice and wheat are usually not produced or eaten as whole grain flour. Experiments are needed to determine whether breeding can improve mineral deposition in the edible portion of the grain, the endosperm. Progress could also come from work on genes that regulate where these compounds are synthesized in the plant. And genetic engineering could provide ways to transfer useful genes across species, so that, for example, the efficient mechanism by which beta carotene is stored in maize could be introduced into strains of rice, which are poor at this process.
None of this breeding work has ever taken place. USDA's Plant, Soil, and Nutrition Laboratory at Cornell University, in cooperation with several CGIAR centers and the University of Adelaide, have begun to examine breeding schemes for raising the level of micronutrients in staples. But the USDA Cornell lab is the only U.S. lab doing so. And it is not a commercial breeding operation. More research is needed, as is simultaneous work on ways to apply lab findings to commercial techniques. There is currently very little genetics work being funded in this area, either, although tweaking of genes could enhance the ability of the entire family of grains to draw iron or zinc from the soil or to synthesize more pro-vitamin A carotenoids.
Further work will be needed to make new strains high-yielding. Then they will have to be grown under local conditions in various countries to see which variations are productive in different soils and climates. Only if the final varieties are hardy and high-yielding will farmers be able to make a profit and be willing to grow them.
Land management techniques could also improve the nutrient content of staples. The manure of livestock contains some useful nutrients, and it is routinely applied as fertilizer on U.S. farms. But in areas such as South Asia, where wood and centralized electricity are scarce, dung is often burned as fuel for cooking. Developing alternative fuel sources in such regions would free up mass quantities of nature's cheapest, most effective, and nutrient-rich soil amendment where it is needed most.
Reintroducing crop diversity on farms by rotating crops will return nutrients to the soils (the "green manure" effect) and result in more locally grown pulses, vegetables, and fruits. This might require innovative subsidies, at least in the near term. Better education, especially of the poor, is needed so people learn how to buy a more nutritious mix of foods and prepare foods so they don't reduce the vitamin or micronutrient metal availability.
Home gardening can help, but well-meaning efforts in many countries have overestimated the nutritional impact and sustainability of home gardens because of unrealistic assessments of water scarcity, temperature extremes, availability of seeds and seedlings, fertility of soils, protection from pests and livestock, and losses due to rotting after the harvest. Local policies can help mitigate these factors, and breeding research could result in more rapidly maturing varieties of plants.
U.S. policymakers can help most directly by supporting interdisciplinary research that makes improved human nutrition an explicit goal of agriculture. Universities could change their reward structure to encourage interdisciplinary work and research on food systems. The government should also study how to make policymakers more aware of the profound negative consequences of micronutrient malnutrition.
Breeding more nutritious staples should be made a national priority. Programs that extend credit, incentives, or subsidies to farmers trying new strains would help turn lab results into real food at the market. Policymakers in developing countries can support efforts to educate farmers about new crop varieties and educate the general population about which mixes of foods are most healthy and how best to prepare them. Credits or subsidies for growing fruits, vegetables, and legumes and for converting from dung to new fuels would also help.
Reducing nutrient losses
The nutrient levels in processed foods can be greatly enhanced by changing milling and processing techniques. Instead of stripping away the nutritious bran and germ, higher-extraction and whole grain flours can be produced. Developing the technology is not a big problem. The real challenge is convincing consumers to accept and look for coarser products made with these ingredients.
Another obvious step is to use the micronutrient-rich byproducts from the milling and polishing of grains. Incredibly, in fuel-starved developing countries, these valuable byproducts are burned as fuel at the processing plant. Bran and germ can be used directly as food supplements for local people. Rice polishings could be, too, if an economical process can be found to stabilize the highly unsaturated lipids they contain. Certainly, all three of these substances could at least be better used as soil amendments. The key to reclaiming this wasted resource is providing low-cost fuel to producers. Creating food markets for the byproducts that would pay more than the cost of alternative fuels could be another strategy.
National governments and international agencies should make policies that support the research and development of cost-effective technology for converting the byproducts of milling and polishing into low-cost edible products that consumers will accept. Technology that will better preserve food after it is harvested and good storage methods for fruits and vegetables that are appropriate for poor households would increase the amount of nutritious foods people consume.
Certain foods promote or inhibit the micronutrients a person can absorb. For example, the compound phytate, contained in many staple seeds and grains, can bind with iron, zinc, and calcium in the intestine, preventing those nutrients from being absorbed. Recent evidence suggests that it may be possible to breed reduced-phytate varieties of soybean and corn, but there is concern about reducing seed vigor and crop productivity in the process. Genetic modification might result in seeds that are just as productive but do not contain excessive amounts of phytate. Another approach would be to develop food production processes, such as fermentation, that help decompose phytate.
The absorption of iron and zinc can be improved by eating foods during meals that contain ascorbic acid (vitamin C), which chemically changes nonabsorbable ferric iron into its more absorbable ferrous iron form and also promotes its absorption. Iron absorption can also be enhanced by eating meat at meals. The mechanism by which this occurs has not yet been fully explained; elucidating it might allow this characteristic to be incorporated into genetically modified plant foods.
A large part of the political solution to this problem is educating people about the right mix of foods to eat and how best to prepare them, including simple techniques such as soaking, which can reduce the amount of inhibitors such as phytate. The simplest advice is for a family to eat at least a modest amount of fruits, vegetables, legumes, and meats, because these are the best sources of micronutrients, and their presence in a meal enhances the body's absorption of micronutrients from all sources. It is important to note that most poor people want to eat these foods; they just can't afford them. Any policy that can improve a family's ability to purchase these foods will help. Governments can also provide tools and resources so local families can grow their own modicum of fruits and vegetables and perhaps raise small livestock.
The most productive work in improving the food system is inherently multidisciplinary, calling for new partnerships that ignore traditional subject, sectoral, and geopolitical boundaries such as those between the agricultural and health communities. Too often, the policies directing the efforts of government agencies, universities, and private institutions have not been based on holistic thinking. Funding and tenure tracks at universities favor specialized research in narrow fields and do little to reward interdisciplinary work.
Nutrition, health, and sustainable economic development must be viewed as instrumental to each other, and research programs must reflect that vision. A fine example is USDA's Fund for Rural America, established in 1996, which supports work that promotes U.S. family farms, much of it interdisciplinary and intersectoral. This program should be expanded and its approach extended to other federal research organizations.
It will also be necessary to reorient our considerable federal research and outreach resources from their traditional focus on domestic agriculture to the larger, global food system. That such a reorientation is in our national interest was suggested by a 1994 report of the now-defunct congressional Office of Technology Assessment, which concluded that the increasing international demand for higher-value and value-added foods gives marketing advantages to our technologically advanced food industry. The same conclusion was reached two decades ago by a National Academy of Sciences study on world food and nutrition. If research can make our own food products more nutritious, there will be even greater demand for them overseas.
Changing our research outlook should start with USDA. Its in-house and extramural research programs must move beyond the narrow scope of its strictly domestic focus. Improving the health of people in other nations stabilizes other countries and governments, which helps the United States politically and creates better markets for U.S. products of all kinds. Besides, producing more nutritious foods is equally beneficial to U.S. citizens.
The structure of the entire world's geopolitical approach to malnutrition, led by FAO, also should be changed. FAO has called for a crash program to greatly increase global food production, but it hinges on further massive increases in irrigation and the spreading of fertilizer-for the existing strains of staple crops. Although the world will need more food, this strategy has been proven faulty: It does nothing to improve micronutrient nutrition or balance the nutrient output of agricultural systems. And the strategy will not even have its intended effect, because without new breeds, production will not increase in the large areas of infertile land where many of the world's poor live. It has been said that FAO's plan is a recipe for prosperity in Kansas, not Kathmandu.
CGIAR remains similarly focused only on food production. Part of the problem is a lack of coordination with the 50 or so U.S. land-grant universities, which have a wealth of agricultural expertise. CGIAR does not even have access to lab work at these universities. In order to broaden its research base and programs, CGIAR should form stable partnerships with these schools. This would ultimately shift the nature of research toward improving nutrition. It would also shore up the agricultural research base in the United States, which the government has been steadily dismantling. The land-grant system was built in the 1800s to transform the knowledge and technology of farmers from local growing to a nationwide system serving the food needs of the nation. In this century, it was charged again with improving production efficiency, and it succeeded wildly, to the point where less than 2 percent of the population is involved in producing the entire country's food supply. Today we face the next great challenge: bringing together food production, nutrition, consumer health, land use, and environmental concerns. We should once again mobilize the land-grant university system.
One model for such a collaboration is the Global Research on the Environmental and Agricultural Nexus (GREAN) initiative, which has been proposed to Congress by a consortium of U.S. land-grant universities. GREAN would revolutionize our approach to international food and agricultural development. Annual support of approximately $100 million would make this program productive.
Nongovernmental organizations such as the Rockefeller and Kellogg Foundations can also play important roles, if they adopt food system principles in their intervention efforts. Foundations should be encouraged to shift more resources to multidisciplinary programs that link local agricultural and public health resources. Community-based organizations, which are working increasingly at the village level in a broad range of activities, are ideally positioned to facilitate improvements in food systems. The federal government can take the lead in forming alliances between them and university and federal programs.
Training our best and brightest young people for interdisciplinary work will help. A food system approach, by its nature, calls for problem-based teams of experts who have different specialties and yet are not overly specialized. Developing such people at the undergraduate level means emphasizing experiential learning methods and dismantling the unnecessary divide between the biological and social sciences. At the graduate level, it requires replacing the traditional professor-as-mentor model with research team internships and other participatory experiences. New modes of teaching, including distance and modular education, should be developed to support lifelong learning in the rapidly changing agricultural, food, nutrition, and social sciences. Such an interdisciplinary environment will only become possible, though, when the reward structures at universities are changed.
The great paradox of the Green Revolution is that even though fewer people are starved of calories, billions of people remain starved of micronutrients. Malnutrition is a political failure and requires a political solution. But there will not be short-term fixes. Success requires vision and a long-term commitment by governments and institutions. Now is the time to begin, before the world's growing population swamps our already struggling food system.
More nutritious foods will not only improve the health of population groups that are at risk for malnutrition but will also bolster the health of all people. Sustainable development cannot be achieved without a population that is better nourished and healthier, more vigorous, productive, and creative. In the food system concept, people are both the ends and the means.
Howarth Bouis, "Enrichment of Food Staples Through Plant Breeding: A New Strategy for Fighting Micronutrient Malnutrition," Nutrition Review, Vol. 54, 1996: 131-137.
G. F. Combs, Jr., R. M. Welch, J. M. Duxbury, M. C. Nesheim, "Food-Based Approaches to Preventing Micronutrient Malnutrition: An International Research Agenda." Summary Report of an International Workshop, Salt Lake City, UT, November 6-9, 1995. Ithaca, NY: Cornell International Institute for Food, Agriculture, and Development, 1996.
FAO, "Preventing Micronutrient Deficiencies: Food Abundance and Diversity are Fundamental," Food Nutrition Agriculture, Vol. 7, 1993: 8-17.
E. Frazao, "The American Diet: A Costly Health Problem," Food/Review, January-April 1996: 2-6.
R. D. Graham and R. M. Welch, Breeding for Staple Food Crops with High Micronutrient Density. Working Paper on Agricultural Strategies for Micronutrients, No. 3. Washington, D.C.: International Food Policy Research Institute, 1996.
J. McGuire, "Addressing Micronutrient Malnutrition," SCN News, No. 9, 1993: 1-10.
World Bank, Enriching Lives: Overcoming Vitamin and Mineral Malnutrition in Developing Countries. Washington, D.C.: The World Bank, 1994.
Ross M. Welch is plant physiologist and lead scientist at USDA's U.S. Plant, Soil, and Nutrition Laboratory in Ithaca, NY. Gerald F. Combs, Jr., is professor of nutrition at Cornell University. John M.Duxbury chairs Cornell's Soil, Crop, and Atmospheric Sciences department.