1.2. Prevalence, causes and consequences of micronutrient deficiencies
1.3. Measures to prevent and control micronutrient malnutrition
The Food and Agriculture Organization of the United Nations (FAO) and the International Life Sciences Institute (ILSI) have developed this publication to provide policy makers and programme planners with information needed to support and implement food-based strategies to prevent micronutrient deficiencies in their respective countries. Food-based strategies are defined as:
a preventive and comprehensive strategy that uses food (i.e., whole, refined forms, processed, fortified or a combination) as a tool to overcome micronutrient deficiencies. This entails intersectoral involvement in the design, implementation, management (including monitoring) and evaluation of flexible programmes. to increase production and consumption of micronutrient-rich foods and their absorption and utilization in the body. Sustainable improvements brought about by such food-based strategies will contribute to nutritional wellbeing and in the long run provide overall economic benefits at both local and national levels.
This manual brings together for the first time in one volume the description and planning considerations for the most pertinent components needed to implement food-based strategies. The purpose of the publication is to assist policy makers and programme planners to understand and initiate and/or reinforce coordinated food-based strategies to prevent micronutrient malnutrition. In addition, this manual presents technical information on the planning and implementation of food-based approaches that can be used to support training of community-level workers and gives attention to specific vulnerable groups. A list of organizations that can provide further technical and financial support to micronutrient programmes is provided in Appendix 1.
Figure
Vitamin A deficiency, often in association with protein-energy malnutrition, principally affects preschool children. It is estimated that almost 250 million children in developing countries are at risk, of whom at least 2.8-3 million are clinically deficient. This Thai fruit vendor's child is fortunate to have access to vitamin A-rich mangoes and other micronutrient-rich foods. Pre-school-age children and adolescent girls, along with women of childbearing age, are especially prone to iron deficiency anaemia, which affects over 2000 million people worldwide. Iodine deficiency disorder is also widespread, with 1500 million people in the world at risk.
Micronutrient malnutrition is a term commonly used to refer to vitamin and mineral nutritional deficiency diseases. Diets which lack adequate amounts of essential vitamins and minerals lead to such diseases. Vitamin A deficiency, iron deficiency anaemia and iodine deficiency disorders are among the most common forms of micronutrient malnutrition. Other micronutrients found in food, including vitamins such as thiamin, niacin, riboflavin, folate, vitamins C and D, and minerals such as calcium, selenium and zinc can also significantly affect health when dietary deficiencies exist. Although the major malnutrition problems are found in developing countries, people in developed countries also suffer from various forms of micronutrient malnutrition. This manual focuses on deficiencies of vitamin A, iron and iodine, the three micronutrient deficiencies of greatest public health concern worldwide.
Vitamin A deficiency (VAD), often in association with protein-energy malnutrition, principally affects preschool children. It is estimated that almost 250 million children in developing countries are at risk, of whom at least 2.8-3 million are clinically deficient. VAD causes night blindness and may lead to xerophthalmia and eventually total blindness. Every year 250,000-500,000 children lose their sight as a result of VAD; two-thirds of these children are likely to die. An estimated 1 million additional children die each year of infectious diseases because VAD impairs their resistance to infection. Commonly available, low-cost foods such as green leafy vegetables and certain yellow fruits and vegetables are rich in provitamin A; regular consumption of these foods in adequate amounts could prevent VAD.
Iron deficiency anaemia affects over 2000 million people worldwide (WHO 1992a). It is estimated that up to half of all anaemia is caused by dietary iron deficiency, although in many cases blood loss from parasites such as hookworm and schistosoma are contributing factors (MacPhail and Bothwell 1992). The groups most affected by anaemia are adolescent girls, women of childbearing age and preschool-age children. In some areas well over half of them may be anaemic, but the disorder is also seen in older children and men (ACC/SCN 1991, WHO 1992b). Anaemia in infants and children is associated with retardation of physical growth and intellectual and psychomotor development, as well as reduced resistance to infections (Lozoff et al. 1991). In adults anaemia causes fatigue and reduced work capacity, exacting a high economic burden on society (Levin 1986). Blood loss in childbirth can be very dangerous for anaemic women and is the primary cause of many maternal deaths. Maternal anaemia may also lead to foetal growth retardation, low-birth-weight infants and increased rates of early neonatal mortality. Increased consumption of meat and fish, which are rich in bioavailable iron, and vitamin Crich foods, which enhance the absorption of iron from plant sources, as well as fortification of commonly eaten foods with iron, can help to prevent anaemia.
Iodine deficiency disorder (IDD) occurs in populations living in areas where iodine in the soil has been washed away by glaciers and rains and in areas of frequent flooding. Over 1500 million people in the world are at risk of IDD. This deficiency may lead not only to visible goitre but also to impaired physical and mental development. IDD is the most common cause of preventable mental retardation. In severe cases, IDD leads to serious disorders such as deaf-mutism, cretinism and increased rates of spontaneous abortion, stillbirth and birth defects. It is estimated that over 200 million people suffer from goitre and 20 million have mental retardation, including 6 million who are classed as cretins as a result of iodine deficiency (WHO 1992a). Seafood, which is a good source of iodine, is often not available to groups vulnerable to iodine deficiency. Adding iodine to salt is the most common and effective method of preventing iodine deficiency.
Table 1.1 shows the distribution of micronutrient malnutrition by regions of the world. Figures 1.1 and 1.2 illustrate, respectively, the prevalence of VAD and IDD.
The primary causes of most micronutrient malnutrition are inadequate intakes of micronutrient-rich foods and impaired absorption or utilization of nutrients in these foods due partly to infection and parasitic infestation, which also increase metabolic needs for many micronutrients. Poverty is often at the root of micronutrient malnutrition and is also linked to inadequate access to food, sanitation and safe water and to lack of knowledge about safe food handling and feeding practices.
Micronutrient deficiencies are a major obstacle to socio-economic development in many countries. They have an immense impact on the health of the population (with high social and public costs), learning ability (with a vast loss of human potential) and productivity (with greatly reduced work capacity). These deficiencies contribute to a vicious cycle of malnutrition, underdevelopment and poverty affecting already underprivileged groups. Children are often the victims of malnutrition, which further jeopardizes the future of their country. Solving micronutrient malnutrition may therefore be seen as a precondition for rapid and sustainable development. Preventing such malnutrition can make possible redirection of funds previously devoted to curative health care and social welfare needs to other development activities.
Table 1.1 Estimated numbers of people (in millions) at risk and affected by the three main forms of micronutrient malnutrition.
Iodine Deficiency Disorders1 |
Vitamin A Deficiency*2 |
Iron deficient or Anaemic3 | |||
Region |
At Risk |
Affected (Goitre) |
At Risk |
Affected (Xerophthalmia) |
|
Africa |
181 |
86 |
52 |
1.0 |
206 |
Americas |
168 |
63 |
16 |
0.1 |
94 |
South-East Asia |
486 |
176 |
125 |
1.5 |
616 |
Europe |
141 |
97 |
- |
- |
27 |
Eastern Mediterranean |
173 |
93 |
16 |
0.1 |
149 |
West Pacific |
423 |
141 |
42 |
0.1 |
1058 |
TOTAL |
1572 |
655 |
251 |
2.8 |
2150 |
* Estimates for vitamin A deficiency are for children from birth to five years of age.
1 WHO/UNICEF/ICCIDD (1994). 2 WHO/UNICEF (1995). 3 WHO (1992B).
Figure 1.1 Countries categorized by degree of public health importance of Vitamin A deficiency, April 1995
Figure 1.2 Current status of Iodine deficiency disorders-global distribution, January 1995
Despite its link to poverty, micronutrient malnutrition will not simply disappear as development occurs in a country. For example, moderate levels of iodine deficiency still exist in some European countries that have failed to take adequate, sustainable measures to overcome the disorder. Governments need to make determined and cost-effective efforts to improve the food supply and the diets of vulnerable groups. Such actions should be seen as an investment in human resource development and nation-building.
Micronutrient malnutrition usually occurs when diets lack variety. The vitamins and minerals needed to prevent micronutrient malnutrition are present in a variety of foods. Policies and programmes. need to be developed and implemented to ensure better year-round access to and consumption of an adequate variety and quantity of good-quality, safe, micronutrient-rich foods.
Micronutrient-rich foods include both foods that contain high levels of vitamin A (retinol) and its precursor (beta-carotene), iron (both haem and non-haem) and iodine and foods which contain factors that enhance micronutrient absorption (e.g., dietary fat and vitamin C). Foods that contain lower levels of micronutrients but are eaten in large quantities may also be considered to be micronutrient-rich. Implied in the need to promote consumption of micronutrient-rich foods is the necessity to reduce the effect of factors which inhibit micronutrient absorption, such as tannins (found in tea) and phytates (found in whole wheat), which inhibit iron absorption, and goitro-gens, which inhibit iodine absorption.
Four main strategies can be used to overcome micronutrient deficiencies:
n dietary diversification,
n food fortification,
n supplementation with vitamin and minerals and
n global public health and disease control measures.
This manual addresses the first two strategies: dietary improvement, which addresses the availability and consumption of micronutrient-rich foods, and food fortification, with a focus on the prevention of micronutrient deficiencies. Measures to prevent and control micronutrient deficiencies, as part of an overall framework to improve nutritional wellbeing, were identified and adopted at the International Conference on Nutrition (ICN), which was jointly convened by FAO and WHO in Rome in December 1992. Representatives of 159 countries endorsed the World Declaration on Nutrition and pledged "to make all efforts to eliminate before the end of this decade... iodine and vitamin A deficiencies... [and]... to reduce substantially... other important micronutrient deficiencies, including iron..." (FAD/WHO 1992a).
Figure
Micronutrient malnutrition usually occurs when diets lack variety. While short-term Interventions have a role in providing specific target groups with vitamin and mineral supplements at certain times, only food-based approaches can prevent micronutrient deficiencies in a sustainable manner for most of the population. Shoppers in this market in Kathmandu, Nepal, have access to both a variety and an abundance of food products.
Exhibit 1.1. Plan of Action for Nutrition: The World Declaration and Plan of Action for Nutrition adopted at the ICN urges governments, in collaboration with international agencies, non-governmental organizations, industry, other experts and local communities, to adopt an appropriate combination of the following strategies to control micronutrient malnutrition: 1. Assess the extent of micronutient malnutrition and develop a national prevention policy based on the distribution, cause and severity of deficiencies and resources available to overcome them. 2. Accelerate efforts to eliminate vitamin A and iodine deficiencies and significantly reduce iron deficiency anaemia by the year 2000. 3. Promote breastfeeding and other sustainable food-based approaches that encourage the production and consumption of micronutrient-rich foods. Processing and preservation techniques that conserve micronutrients should be promoted when micronutrient-rich foods are available only on a seasonal baste. 4. Use micronutrient supplementation on a short-term basis to reinforce dietary approaches in severely deficient populations. Supplementation should be directed at women of reproductive age, infants and young: children, the elderly, refugees and displaced persons and should be phased out as soon as food-based strategies enable adequate consumption of micronutrients. 5. Promote food fortification when existing food supplies fail to provide adequate levels of micronutrients in the diet. Iodisation of all salt for human and livestock consumption is the most effective long-range measure for correcting iodine deficiency. 6. Ensure that nutrition education programmes promote the consumption of micronutrient-rich foods and provide information on food preparation, nutritional value and other factors that affect micronutrient status. 7. Support research on the role of micronutrients in health and disease, factors affecting the bioavailability of nutrients in food, indigenous methods of food preparation and processing that affect micronutrient availability and improvement of techniques to assess and correct micronutrient deficiencies. 8. Develop sustainable institutional capacities and human resources for the contra and prevention of micronutrient deficiencies, including the training of professionals, non-professionals and community leaders. 9. Consider establishing a national committee to coordinate micronutrient deficiency control activities, with authority, legislation and infrastructure that resect national commitment to overcoming the problem. 10. Ensure that the nutrient content of food used for emergency food aid meets micronutrient standards and, to the extent feasible, that such food is culturally acceptable. |
The Plan of Action for Nutrition, which was adopted unanimously by governments attending the ICN, included strategies specifically to address the prevention and control of micronutrient deficiencies, with priority given to food-based strategies (see Exhibit 1.1). food-based approaches were also emphasized at the Policy Conference on Ending Hidden Hunger (Montreal 1991), held to pursue the micronutrient goals of the World Summit for Children (New York 1990). At these conferences, policy makers and planners recognized that short-term interventions have a role to play in providing specific target groups with vitamin and mineral supplements for varying periods of time. However, it was stressed that only food-based approaches can prevent micronutrient deficiencies in a sustainable manner for most of the population.
The apparent simplicity and rapid start-up times of vitamin and mineral supplementation programmes to overcome micronutrient deficiencies have in the past made such programmes attractive to governments, international agencies and the donor community. However, in practice, many such programmes have proven to be less effective, more difficult to manage and more costly than expected. In many developing countries, there is increasing interest in developing broader and more balanced approaches to the control of micronutrient deficiencies, including food-based strategies.
Increased availability of micronutrient-rich foods, along with increased educational and marketing activities, can greatly increase consumption of these foods among vulnerable groups. Furthermore, food-based strategies that provide these micronutrients offer the prospect of years of sustainable benefits. Policy-makers and planners should not be hindered from initiating food-based strategies because of a few widely publicized projects that failed - generally because of poor planning and narrow focus and the perception that food-based approaches take time to implement. The time and effort to implement these strategies offer the potential for far-reaching and long-lasting benefits. (See Exhibit 1.2.)
Exhibit 1.2. Benefits of Food-based Strategies The benefits of hod-based strategies go beyond the prevention and control of micronutrient deficiencies.
Specific benefits of food fortification include the following: n It can provide wide population coverage. Combined nutrient fortification can address multiple deficiencies. n It encourages industries to be socially concerned and to add nutritional value to their products. It provides opportunities for consumers to become involved in food quality issues and creates demand for safe, wholesome food. |
The World Bank has estimated that investing in programmes to prevent micronutrient deficiencies is among the most cost-effective of all interventions to improve health (World Bank 1993). Demonstrating the cost-effectiveness of various approaches to improving micronutrient status is extremely important in times of diminishing resources and constrained national budgets. Yet estimating the true costs of various approaches and their benefits in monetary terms is difficult and will vary from country to country. Gross and Tilden (1988) suggested that dietary modification was the most cost-effective measure to improve vitamin A status.
Dietary change programmes may be more sustainable at the family and community levels when food sources are locally available and have the advantage of providing other nutrients and dietary factors to improve absorption and utilization of micronutrients (Gopalan 1994). These programmes also do not have to rely for effectiveness on a regular supply of pharmaceuticals (World Bank 1994).
Some recent projects to eliminate micronutrient malnutrition illustrate the costs involved in food-based strategies. The Social Marketing Vitamin A-Rich Foods Project, conducted from 1988 to 1991 in northeast Thailand, promoted the production and consumption of vitamin Arich food at an estimated cost of US$0.42 per capita (Smitasiri et al. 1993). In Indonesia, the cost of increasing consumption of dark green leafy vegetables was estimated at US$0.28 per mother/child (Pollard 1989). The per capita costs of food-based strategies are likely to decrease as they are implemented on a larger scale. One of the largest initiatives to date was the Worldview International Foundation Nutritional Blindness Prevention Programme in Bangladesh, which aimed to increase both production and consumption of carotene-rich foods. It was implemented from 1989 to 1993 in the Gaibandah district (population 1.9 million), where it cost only US$0.13 per capita per year. Compared with nearby control districts, it substantially raised household production of several high-carotene foods and within only three years had a positive impact on the diet of young children (Greiner and Mitra 1995).
