Poverty – not insufficient global food production – is the root cause of malnutrition. Poor families lack the economic, environmental, or social resources to purchase or produce enough food. In rural areas, land scarcity and degradation, water salinity due to overirrigation, soil erosion, droughts, and flooding can all undermine a family’s ability to grow enough food. In urban areas, low wages, lack of work and underemployment, and rapid changes in food prices often place food supplies out of the reach of poor households. War and civil strife almost always cause upheaval in the food system and often result in widespread famine, as with the civil wars in Rwanda and Somalia.
Although overall trends are positive, with the proportion of people with malnutrition declining, many remain at risk, and some regions are hit especially hard. (See Countries with Populations at Risk of Inadequate Nutrition.) Between 1990 and 1992, approximately 841 million people – or 1 out of every 5 people in the developing world – did not have access to enough food for healthy living (1).
| Countries with populations at risk of inadequate nutrition | |
 |
|
| Source: See Environmental risks to human health: New indicators | |
The health consequences of inadequate nutrition are enormous. According to one estimate, malnutrition contributed to roughly 12 percent of all deaths in 1990 (2). Although much of this toll stems from underconsumption of protein and energy, deficiencies in key micronutrients such as iodine, vitamin A, and iron also undermine health (3).
When poverty limits an adequate and varied diet, deficiencies of iron, iodine, and vitamin A often occur simultaneously with protein-energy malnutrition. Geography and soil characteristics also influence the amount of these nutrients commonly found in food. Mountainous areas are often deficient in ioddine; the most severely deficient regions are the Himalayas, Andes, European alps, and mountains of China (4). Areas with arid, infertile land or heavy rainfall and humidity may be deficient in vitamin A (5). Africa, the Andean region of South America, and many parts of Asia are at risk from not only protein energy malnutrition, but also from all three main micronutrient deficiencies because of both poverty and environmental factors.
Iron deficiency is the most common micronutrient disorder. In developing countries, 40 percent of nonpregnant women and 50 percent of pregnant women are anemic, and 3.6 billion people suffer from iron deficiencies (6). The problem is most severe in India, where 88 percent of pregnant women are anemic. Anemia increases the risk of death from hemorrhage in childbirth. Iron deficiencies can also reduce physical productivity and affect a child’s capacity to learn (7).
Globally, some 42 million children under age 6 have mild to moderate vitamin A deficiency. In its severe form, vitamin A deficiency can cause blindness; indeed, it is the single most important cause of childhood blindness in developing countries. About 250,000 to 300,000 children go blind annually, and 50 to 80 percent of those die within 1 year (8). Up to 3 million more children suffer lesser but still serious effects, such as loss of night vision. An estimated 254 million children of preschool age are at risk of vitamin A deficiency (9).
Iodine deficiency is the world’s leading single cause of preventable brain damage and mental retardation. In 1990, some 26 million people suffered from brain damage associated with iodine deficiency (10). An estimated 1.5 billion people are at risk of iodine deficiency disorders (IDD), and 655 million people are affected by goiter, which is the enlargement of the thyroid gland, an indicator of IDD (11). Where this deficiency is endemic, the entire population may be affected, with different symptoms appearing in different age groups. In pregnant women, for instance, iodine deficiency may cause irreversible brain damage in the developing fetus (12).
The combination of malnutrition and infectious disease can be particularly pernicious. Protein-energy malnutrition can impair the immune system, leaving malnourished children less able to battle common diseases such as measles, diarrhea, respiratory infections, tuberculosis, pertussis, and malaria. Vitamin A deficiencies are often worsened by infectious disease; and reciprocally, poor vitamin A status is likely to prolong or exacerbate the course of an illness such as measles (13). Similarly, malaria parasites, which require iron in order to multiply in blood, can cause or exacerbate anemia (14). Malnutrition can also heighten the adverse impacts of toxic substances. Deficiencies of protein and some minerals, for example, can significantly influence the absorption of lead and cadmium into the body (15)(16).
The consequences of food and nutrition shortfalls are enormous. Africa and Southeast Asia confront problems of both malnutrition and such diseases as diarrhea, malaria, and measles – a combination that is likely to increase the toll that either problem would take alone. In rapidly industrializing cities with high levels of malnutrition as well as disease and growing industrial pollution, residents may confront a triple burden of malnutrition, infection, and toxic pollution.
References and notes
1. Food and Agriculture Organization of the United Nations (FAO), The Sixth World Food Survey (FAO, Rome, 1996), pp. v-vi.
2. Christopher J.L. Murray and Alan D. Lopez, eds. The Global Burden of Disease: Volume 1 (World Health Organization, Harvard School of Public Health, and The World Bank, Geneva, 1996), p. 311.
3. The World Bank, World Development Report 1993: Investing in Health (The World Bank, Washington, D.C., 1993), p. 75.
4. World Health Organization (WHO), United Nations Children’s Fund (UNICEF), and the International Council for the Control of Iodine Deficiency Disorders, “Global Prevalence of Iodine Deficiency Disorders,” Micronutrient Deficiency Information System Working Paper No. 1 (WHO, Geneva, 1993), p. 7.
5. World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF), “Global Prevalence of Vitamin A Deficiency,” Micronutrient Deficiency Information System Working Paper No. 2 (WHO, Geneva, 1995), p. 5.
6. World Health Organization (WHO), The World Health Report 1997: Conquering Suffering, Enriching Humanity (WHO, Geneva, 1997), p. 51.
7. Op. cit. 3.
8. Henry M. Levin et al., “Micronutrient Deficiency Disorders,” in Disease Control Priorities in Developing Countries, Dean T. Jamison et al., eds. (Oxford University Press, New York, 1993), p. 424.
9. Op. cit. 5, pp. ix, 16.
10. Op. cit. 4, pp. 5, 8.
11. Op. cit. 4, p. 5.
12. Op. cit. 4, p. 5.
13. Andrew Tomkins and Fiona Watson, Malnutrition and Infection: A Review (United Nations Administrative Committee on Coordination/Subcommittee on Nutrition, WHO, Geneva, 1989), pp. 5-6.
14. Ibid., p. 7.
15. Howard Hu, Sudha Kotha, and Troyen Brennan, “The Role of Nutrition in Mitigating Environmental Insults: Policy and Ethical Issues,” Environmental Health Perspectives, Vol. 103, Supplement No. 6 (1995), p. 186.
16. Kathryn R. Mahaffey, “Nutrition and Lead: Strategies for Public Health,” Environmental Health Perspectives, Vol. 103, Supplement No. 6 (1995), p. 193.
