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Part I. Causes of malnutrition

Part I. Causes of malnutrition

Chapter 1. International nutrition and world food problems in perspective

These are the opening sentences of the World Declaration on Nutrition produced by the FAO and World Health Organization (WHO) International Conference on Nutrition (ICN) held in Rome in December 1992. That important conference reviewed the current nutrition situation in the world and set the stage for markedly reducing these unacceptable conditions of humankind. Reaching the ICN goal is possible. Most of the work will need to be done in the developing countries by their own people. However, cooperative work across nations and across disciplines is also essential.

This book is aimed to help move forward the noble objectives elaborated by the ICN. It is hoped that a comprehensive text that describes the nature of the problems, their causes and ways to deal with them can be helpful. A brief review highlighting international food and nutrition issues can help to bring the most important issues into perspective.

The ICN declaration goes on to state:

The scale of the problem

Protein-energy malnutrition (PEM), vitamin A deficiency, iodine deficiency disorders (IDD) and nutritional anaemias - mainly resulting from iron deficiency or iron losses - are the most common serious nutritional problems in almost all countries of Asia, Africa, Latin America and the Near East.

Nutrition and development: a global assessment, prepared by FAO and WHO for the ICN, reviewed all available current information on the prevalence of hunger and malnutrition and provided a global estimate for the various regions of the world. FAO updated the estimates of the chronically undernourished population of the world for the Sixth World Food Survey and in preparation for the World Food Summit (Table 1), and WHO updated the estimates for iodine, vitamin A and iron deficiencies in 1995 (Table 2). The figures suggest that one of every five persons in the developing world is chronically undernourished, 192 million children suffer from PEM and over 2 000 million experience micronutrient deficiencies. In addition, diet-related non-communicable diseases such as obesity, cardiovascular disease, stroke, diabetes and some forms of cancer exist or are emerging as public health problems in many developing countries.

While these numbers and trends are alarming, progress has been made in reducing the prevalence of nutritional problems, and many countries have been remarkably successful in addressing the issues of hunger and malnutrition. For the developing countries as a whole there has been a consistent decline since the early 1970s in the proportion and absolute number of chronically undernourished people. From 1969 to 1971 approximately 893 million people were chronically undernourished, compared with 809 million from 1990 to 1992; these figures represent a drop from 35 to 20 percent of the population of these countries. The current - and achievable - challenge is to build upon and accelerate the progress that has been made.

FAO and WHO data indicate improvements of the nutritional situation in Asia and Latin America from 1980 to 1990 but a deterioration in sub-Saharan Africa. Although the prevalence of underweight children remained virtually unchanged in sub-Saharan Africa during that decade (increasing from 29 to 30 percent), the prevalence rates are much better than in South Asia, where about 59 percent of children - almost twice the prevalence in Africa - were underweight in 1990 (Table 3). In the same year, in total numbers, five times as many children were underweight in South Asia (101 million) as in sub-Saharan Africa (19.9 million).

Many nutritional statistics show the numbers of persons who have overt evidence of a deficiency. However, "at risk" populations are not often identified. In nutrition, as in public health, people considered at risk of developing malnutrition should be among the primary concerns. Prevention becomes more feasible and cost effective if groups at risk are identified and the causes of malnutrition are clearly understood.

One of the most dramatic aspects of the global nutrition situation is the extent of famine, hunger and starvation. While good progress has been made in averting famine, especially in Asia, these horrifying conditions persist throughout the world. Their occurrence is commonly attributed to drought and other natural disasters, but war, civil unrest and political instability have far greater importance. In the mid-1990s, hunger and malnutrition resulting from civil strife are serious problems in many parts of the world including Europe (particularly former Yugoslavia), Asia (for example, Afghanistan), the Near East (Iraq) and most extensively Africa. Tragically, civil strife often affects not only the countries in turmoil but also those that provide hospitality to the refugees who flee their homes in terror. In mid-1994, the United Republic of Tanzania accepted about 500 000 refugees from Rwanda, most of them in less than one week. Their arrival more than doubled the population of the resource-poor region, which welcomed them as best it could. The influx placed overwhelming pressure on local resources and necessitated a major international effort to prevent an increase in nutrition and health problems among the local people as well as to contain these problems among the refugees.

TABLE 1

Prevalence of chronic undernutrition in developing regions

Region

Percentage of population

Number (millions)

 

1969-1971

1979-1981

1990-1992

1969-1971

1979-1981

1990-1992

Latin America and the Caribbean

18

13

14

51

46

61

Near East and North Africa

25

10

10

44

24

32

Sub-Saharan Africa

36

39

41

96

140

204

East and Southeast Asia

41

27

16

468

371

262

South Asia

33

33

22

233

297

250

Continental Africa

34

33

34

116

148

211

Developing regions

35

27

20

893

878

809

TABLE 2

Population at risk of and affected by micronutrient malnutrition (millions)

Region1

Iodine deficiency disorders

Vitamin A deficiency

Iron deficiency or anaemia

 

At risk

Affected (goitre)

At risk2

Affected (xerophthalmia)

  

Africa

181

86

31

1.0

206

Americas

168

63

14

0.1

94

Southeast Asia

486

176

123

1 7

616

Europe

141

97

-

-

27

Eastern Mediterranean

173

93

18

0.2

149

Western Pacific3

423

141

42

0.1

1 058

Total

1 572

655

228

3.1

2 150

1 WHO regions.

2 Preschool children only.

3 Including China.

TABLE 3

Prevalence of underweight1 children under five years of age, by region

Region

Percentage underweight

Number underweight (millions)

 

1980

1985

1990

1980

1985

1990

Sub-Saharan Africa

28.9

29.9

29.9

19.9

24.1

28.2

Near East/North Africa

17.2

15.1

13.4

50

5.0

4.8

South Asia

63.7

61 1

58.5

89.9

100.1

101,2

Southeast Asia

39,1

34 7

31.3

22.8

21.7

19.9

China

23.8

21,3

21.8

20,5

21,1

23,6

Central America/Caribbean

17.7

15.2

15.4

3 1

2.8

3.0

South America

9.3

8.2

7.7

3.1

2.9

2.8

Global (average percentage/total number)

37.8

36.1

34.3

164

178

184

Source: UN ACC/SCN, 1992a.

1 Underweight is defined as weight-for-age less than -2 standard deviations from the mean.

Nutrition improvement: Nature and evolution

Data from around the world show that the causes underlying most nutrition problems have not changed very much over the past 50 years. Poverty, ignorance and disease, coupled with inadequate food supplies, unhealthy environments, social stress and discrimination, still persist unchanged as a web of interacting factors which combine to create conditions in which malnutrition flourishes. However, what does change greatly is the approach to tackling malnutrition. Each decade or so witnesses a new dominant framework, paradigm, panacea or quick fix claimed to be capable of reducing the malnutrition problem greatly before ten years have passed.

During the 1950s and 1960s, kwashiorkor and protein deficiencies were seen as the major problems. Quick fixes such as fish protein concentrate, single-cell protein or amino acid fortification and increased production of protein-rich foods of animal origin were the strategies proposed for the control of malnutrition in the tropics and subtropics.

During the late 1960s and 1970s, the term "protein-energy malnutrition" entered the literature. Increasing protein and energy intake by children was the solution, and nutrition rehabilitation centres and applied nutrition programmes (ANPs) were offered up as sure strategies.

The 1974 World Food Conference began a decade of macroanalysis which placed first nutrition planning and then nutritional surveillance among the dominant strategies for the countries most affected. Economists began to take over from nutritionists and paediatricians as the architects of new policies, with much talk about national food security and agencies such as the World Bank stressing income generation.

In 1985 the International Monetary Fund (IMF) began to push structural adjustment, and WHO and UNICEF reinvented ANPs, which they renamed Joint Nutrition Support Programmes (JNSPs). In the early 1990s the subject of micronutrients pushed PEM to the background, as nutritionists, international agencies and universities attempted quick fixes to control vitamin A deficiency, anaemia and IDD. The micronutrient wave has not yet crested, and very large sums of money are likely to be provided by the World Bank, the United States Agency for International Development (USAID) and others to address this hidden hunger". This effort is, in part, a response to the goals set by the 1989 World Summit on Children and the 1992 International Conference on Nutrition, which include the virtual elimination of vitamin A deficiency and IDD before the turn of the century.

Increased funding is needed if improvements in nutrition are to be achieved. However, there is a danger that the limited resources available may be diverted towards the development of new quick-fix strategies for micronutrient deficiencies. Little, then, will remain for addressing the underlying and basic causes of malnutrition. The quick fix addresses only the immediate causes of a problem, scratching the surface and providing no sustainability.

It is well recognized that inappropriate development strategies also contribute to the underlying causes of hunger in many countries. Policy reform and the institution of appropriate development and macroeconomic policies are advocated by many economists to improve nutrition. The ICN also emphasized that developing countries must work to ensure that development policies and projects are designed to include nutrition improvement objectives. Furthermore, in the low-income food-deficit countries, where most of the world's malnourished people live, economic growth and poverty alleviation must be based on better development of agricultural resources and improvement of food supplies. This approach should promote sustainable development, expand employment opportunities and improve access to food by the poor. Free and fair trade is clearly important for stimulating economic growth, and the prices for primary and processed agricultural products must be adequate to ensure sustained development. The primary producers must receive fair prices for their products, labour and use of resources.

It has to be recognized that inappropriate application and transfer of technology and even aspects of certain development projects can have negative as well as positive consequences for health and nutrition in poor countries. It is important that such possible negative consequences be identified early and that measures be taken to offset and prevent them. It may be more important to enhance during project preparation those aspects that will have a positive impact for maximum nutritional benefits.

There is also a greater realization that the poor should be more involved in solving their own problems and that the causes of malnutrition and the different levels of society implicated vary from place to place. People should be able to ask appropriate questions relevant to their situation, at the national, local or even family level, and they should be aware of the multisectoral nature of the problem of malnutrition. They can then, together with persons from different disciplines, suggest actions that might be taken at different levels. During the past ten years a good deal has been written about local participation in development decisions and programmes. The innate wisdom of peasants, with regard to agriculture as well as other development-related matters such as health and nutritional status, has finally been widely acknowledged.

It has also been recognized that international and national policies and actions can influence nutritional status in the rural villages and city slums of developing countries. The State may determine taxes, control prices, run national institutions and oversee a legal system. Almost all of these factors influence, and some of them are influenced by, the formal and informal institutions in society. Clearly these institutions influence the causes of malnutrition. Thus the presence or absence, the relevance and the quality of formal local institutions such as agriculture advisory services, health centres, primary schools and community centres have a very important role in areas related to nutrition. But the more informal institutions can also have a role in influencing food, health and care. The most important of these is the family; others include groups of friends and religious, sporting or social groups.

The realization that malnutrition is not just a food problem has been appreciated for many years, but the concept of the importance of giving consideration to food, health, education and care is of more recent origin. It is vital that this thinking continue to develop and to move forward steadily, in the place of erratic leaps in pursuit of fashion or funding. For a healthy approach, in the next ten years, the achievements should be reassessed; old strategies that have sound logic and a successful record should be protected and supported, and new policies promoted only when needed. This approach is possible with both discipline and flexibility, and examples of its success are visible today.

A framework for causes of malnutrition

Malnutrition or undesirable physical or disease conditions related to nutrition can be caused by eating too little, too much or an unbalanced diet that does not contain all nutrients necessary for good nutritional status. In this book the term malnutrition is restricted to undernutrition, or lack of adequate energy, protein and micronutrients to meet basic requirements for body maintenance, growth and development.

An essential prerequisite to the prevention of malnutrition in a community is the availability of enough food to provide for the nutrient needs of all people. For adequate food to be available, certainly there must be adequate food production or sufficient funds at the national, local or family level to purchase enough food. Availability of food, however, is just part of the picture. It is now recognized that malnutrition is only the overt sign, or symptoms, of much deeper problems in society.

Inadequate dietary intake and disease, particularly infections, are immediate causes of malnutrition. It is obvious that each person must eat an adequate amount of good-quality and safe food throughout the year to meet all nutritional needs for body maintenance, work and recreation, and for growth and development in children. Similarly, one must be able to digest, absorb and utilize the food and nutrients effectively. Poor diets and disease are often the result of insufficient household food security, inappropriate care and feeding practices and inadequate health care. It is now understood that good nutrition depends on adequate levels of all three of these factors.

Other factors can also contribute to unavailability or inadequacy of resources for afflicted families. Every rural community or society has certain natural or human resources as well as a certain potential for production. A host of factors influence what and how much food will be produced and how and by whom it will be consumed.

The proper use of resources may be affected by economic, social, political, technical, ecological, cultural and other constraints. It may be affected by lack of tools or training to use them and by limited knowledge, skills and general ability to use the resources. The cultural context is of special importance for its influence, especially at the local level, on the use of resources and the establishment and maintenance of institutions.

Malnutrition may manifest itself as a health problem, and health professionals can provide some answers, but they alone cannot solve the problem of malnutrition. Agriculturists, and often agricultural professionals, are required to ensure that enough foods, and the right kinds of food, are produced. Educators, both formal and non-formal, are required to assist people, particularly women, in achieving and ensuring good nutrition. Tackling malnutrition often requires the contributions of professionals in economics, social development, politics, government, the labour movement and many other spheres.

Promotion and protection of nutritional well-being: The ICN approach

The International Conference on Nutrition developed nine common areas for action to promote and protect the nutritional welfare of the population:

Addressing issues under these themes facilitates the development of a common understanding of nutrition problems by various sectors and allows a more focused approach for working towards solutions. Taking this thematic approach to nutrition problems should ensure that each of the many facets of a problem are noted, which should allow each sector or agency to assess how it can best work for improvements. These issues are discussed in detail in Part V.

The six Ps

By shedding the sectoral perspective and adopting a multisectoral, multidisciplinary one, it is possible to see the causes of malnutrition in a different guise and to focus the development of solutions less narrowly than in the past. Each case will be different, of course, and the extent to which one cause or one area of expertise predominates will vary with the circumstances. However, six determinants of malnutrition are especially important, although none is usually the only cause of malnutrition or the only discipline that needs to be involved in nutrition strategies.

These six determinants - the six Ps - are:

Production

The production of food comes mainly from agriculture. Most countries have a ministry of agriculture and different kinds of agricultural staff whose contributions are very important to nutrition, but adequate national agricultural and food production does not guarantee good nutritional status for all people. As described in Chapter 2, there have been remarkable developments in agriculture in the past four decades. High-yielding varieties of the important cereals (rice, wheat and maize) have been successfully developed, and much progress has been made in increasing food yields per hectare of land. Some countries that are self-sufficient in their production of staple foods, however, still have the highest prevalence of malnutrition. Agriculturists and agriculture ministries have an absolutely vital role in improving nutritional status, but they cannot win the battle against malnutrition without action from other ministries and without other expertise. Other areas such as food safety, food losses and food storage influence the availability of food. Consideration has to be given to food demand as well as food production.

Preservation

Despite the remarkable progress made in increasing food production at the global level, approximately half of the people of developing countries do not have access to an adequate food supply. A substantial part of the food produced is lost, for various reasons, before it can be consumed. It has been estimated that about 25 percent of the grains produced are lost because of bad post-harvest handling, spoilage and pest infestation. Losses of easily perishable fruits, vegetables and roots have been estimated to be about 50 percent of what is grown. After food reaches the home, about 10 percent is lost in the kitchen. Therefore, ensuring that appropriate measures are taken to prevent food losses during harvesting, transportation, storage, processing and preservation should be an integral component of any programme for the prevention of malnutrition and the improvement of the population's access to food in developing countries. Processing can also add nutritional and economic value to foods. Adequate measures for the provision of safe and quality food should also be taken.

Population

The population question and the relationship of fertility and the availability of family planning to nutrition are discussed in Chapter 5. The food available per person in a family, a district or a nation depends on the amount of food produced or purchased divided by the number of people who have access to that food. A family of eight that produces and purchases the same amount of food as a family of four has less food available per person. However, it also needs to be recognized that among producing families, larger family size can also lead to greater family productivity.

In some countries the population problem is considered to be of great importance, and overpopulation, family size and child spacing are considered important determinants of malnutrition. Demographers study population, and many countries have a government body, often in the ministry of health, responsible for family planning. Birth spacing may deserve a very high priority. However, as with production, it is naive to believe that in any country population control or successful family planning will by itself solve the problems of hunger and malnutrition.

Poverty

Poverty is often stated to be the very root cause of malnutrition. Certainly in most countries it is mainly, and sometimes only, the poor whose children suffer from severe or moderate PEM or show evidence of vitamin A deficiency. In contrast, nutritional anaemias and IDD may not be confined to the poor.

Economists are the professionals who study poverty and income and suggest economic solutions for problems of poverty which may be related to malnutrition. Most governments have a group of economists working in the ministry of finance and sometimes also in a ministry of economic planning.

The experience of many developing countries shows that a major reduction in poverty would have a significant impact on rates of PEM in most countries and communities. Efforts to reduce poverty, raise incomes, lower food prices and redistribute wealth, as well as a host of other economic policies, can have a major impact on nutrition. But just as agriculturists and demographers alone cannot solve the nutritional problems of a nation, so also economic actions alone do not usually rid a country or area of malnutrition. In some cases raised incomes have not resulted in major reductions in malnutrition and certainly have not led to its eradication.

Poverty takes many forms and is expressed in many ways. Inadequate household income is one manifestation, but poor communities and nations lack the wealth needed to build and support schools and training programmes to improve water supplies and sanitation and to provide needed health and social services.

Politics

All countries have a mechanism to create and implement policies in spheres of development. The systems differ from one country to another, but agriculture, health, education, economic and other related policies strongly influence the well-being of the people, including their nutritional status. Some governments take their obligations seriously. If government leaders take the right to freedom from want seriously, then they also respect the right to freedom from hunger, freedom from lack of health services, freedom from poor housing and so on. These conditions, however, also depend on the resources of the country. The way in which political ideology can have a significant influence on malnutrition is probably through government acting to ensure some level of equity. Equity does not imply equality, it simply means a reasonable or relatively fair access of all people to the essential resources such as housing, education, food and health care. Policies directed towards improving access of women to resources for income generation, education and health care would particularly improve the nutritional welfare of the family and children.

Pathology

This sixth P connotes disease. Physiology refers to the normal functioning of the body and its organs and cells. Pathology refers to abnormal function and to disease. Much malnutrition in the world is caused or influenced not only by shortage of food, but by disease.

The relationship between malnutrition and infection has been extensively studied and documented. There is no doubt that common infections such as diarrhoea, respiratory disease, intestinal worms, measles and acquired immunodeficiency syndrome (AIDS) are important causes of malnutrition. These relationships are discussed in Chapter 3. In addition, certain non-infectious diseases may also be causes of malnutrition. Examples of these include a variety of malabsorption syndromes (conditions where the body does not absorb nutrients properly), many cancers and malignancies and some psychological illnesses.

Ministries of health and a variety of health personnel in the public and private sectors are responsible both for treatment of disease and for public health or preventive measures. In many countries the responsibility for government nutrition policies rests with the ministry of health, and often national institutes of nutrition fall under this ministry. Certainly health measures to prevent disease, especially infections, and also actions to provide medical care and appropriate treatment will help very much to reduce the extent of malnutrition in a country or a community. Health measures alone, however, have never been able to eliminate malnutrition totally.

A multidisciplinary perspective

This discussion of the six Ps, namely production, processing, population, poverty, politics and pathology, is designed to illustrate the complexity of both the underlying causes of malnutrition and the solutions. It illustrates that agriculturists, industrialists, demographers, economists, politicians and health personnel all have important roles in controlling malnutrition. It is also clear that no one ministry or single group of professionals is likely to eliminate hunger and malnutrition in society. Nutritionists, food scientists and others work across all these lines, and in a properly functioning national food and nutrition strategy they will collaborate with professionals in several of these disciplines as well as others. Achieving good nutrition may also require experts in anthropology, sociology and community development; it requires a good transport and marketing system; it benefits greatly from an education system that provides school for all, especially females, and guarantees the highest levels of literacy; and it may involve many other actors. Nutrition strategies are truly multisectoral, which may sometimes present more difficulties at the national level than at the local or community level. Community participation, with the assistance of actors from different sectors including at least agriculture, health, community development and education, will often be needed to meet the challenge of good nutrition for all. The chapters in this book are designed to allow persons from different disciplines to understand the complexities of the nutrition problem but also to see that a variety of quite simple actions can contribute to improving nutrition.

Chapter 2. Food production and food security

A national food policy should be a part of an overall nutrition strategy with household food security for all people as a central objective. Achieving food security includes ensuring:

For all households to be food secure, each must have physical and economic access to adequate food. Each household must always have the ability, the knowledge and the resources to produce or procure the foods that it needs. Nutritionists stress also the need for the food to provide for all the nutritional requirements of the household members, which means a balanced diet providing all necessary energy, protein and micronutrients.

Beyond household food security is the need to encourage food distribution that ensures good nutritional status for all the members of the household. The right to an adequate standard of living, including food, is recognized in the Universal Declaration of Human Rights. National development policies should include food security as an objective, and achieving food security for all is an indication of success.

In nutrition there exists the paradox that while undernutrition leads to a serious set of health problems, overconsumption of food and of certain dietary components carries other risks to health. This book is particularly concerned with undernutrition. This chapter considers food security, at both the national and household levels, and food policy.

National food security

Food security is often defined as access by all people at all times to sufficient food required for a healthy and active life. It is now widely accepted that most of the undernutrition in developing countries is due to inadequate intake of both protein and energy and that it is often associated with infectious diseases.

In the past, protein deficiency was overemphasized as an important nutrition problem in the world. Commercial production of relatively expensive protein-rich foods, amino-acid fortification of cereal grains, production of single-cell protein and other ventures were offered as panaceas for the world's nutrition problems. These ventures only reduced the problem of protein-energy malnutrition (PEM) by a very small degree. Thus, in the context of combating malnutrition, attempts at making small changes in the amino-acid pattern of cereal grains by means of genetic manipulation are much less useful than increasing the yields per hectare of cereals and other food crops or enabling people to purchase the foods they need.

Satisfying the energy needs of a population, which should be the first goal of a food policy, has been a relatively neglected matter. In most populations where the staple food is a cereal such as rice, wheat, maize or millet, serious protein deficiencies seldom occur except where there is also an energy or overall food deficiency. The reason is that most cereals contain 8 to 12 percent protein and are often consumed with moderate quantities of legumes and vegetables. Protein deficiencies in people consuming these diets are mainly confined to very young children suffering increased nitrogen losses because of frequent infections. However, among populations whose staple food is plantain, cassava or some other food with a low protein content, protein intakes may be a problem for greater sections of the population.

A modest increase in cereal, legume, oil and vegetable consumption by children will greatly reduce the prevalence of PEM and growth deficits for children in developing countries, especially if combined with control of infectious diseases. Breastfeeding during the first few months of life can ensure an adequate diet, whereas bottle-feeding is a major cause of diarrhoea and nutritional marasmus (see Chapter 7).

Food availability (food supply)

To nourish a population adequately, there must be a sufficient quantity and variety of good-quality and safe food in the country. Therefore, in most low-income food-deficit countries a fundamental strategy of food policy is to improve and increase food production - a domain for agriculture experts. Clearly, decision-makers in the agriculture sector need to be aware of the nutritional needs of the population and to understand the nutritional implications of their actions.

Most food in the world comes from cereals. The second largest amount of food comes from root crops, followed by legumes or pulses. In round figures, the world produces about 2 000 million tonnes of cereals, 600 million tonnes of root crops and 60 million tonnes of pulses per year. In addition, about 85 million tonnes of fats and oils and 180 million tonnes of sugar are produced worldwide each year. Developing countries produce more of all these items than do industrialized countries. In contrast, industrialized countries produce more foods of animal origin meat, milk and eggs, for example - than do the developing countries.

In the last few decades, truly remarkable advances have influenced food production. Agricultural research has developed and made available new varieties of the main cereals: rice, maize and wheat. These new varieties produce much higher yields per hectare than the old varieties. Some have a shorter period between planting and harvesting, and some are relatively resistant to disease. However, most of these new varieties require increased fertilizer use. In addition, many of the improved rice varieties and some of the wheat and maize varieties require irrigation or more water. Both of these options may be economically unfeasible for most poor farmers. In general, cultivation of improved varieties is more suitable for large, economically comfortable farms with access to agricultural inputs. It should be a major agricultural policy objective to see that more resource-poor farmers have adequate access to such inputs.

The development of these new varieties - the green revolution - has allowed much higher yields of cereals for a given area of land. As population pressure increased on arable land, the green revolution offered an alternative to the old method of increasing production, namely expanding the area of land cultivated.

Average world food production has kept pace with or very slightly exceeded the increase in world population. In round figures, 2 700 kcal are available per person per day in the world. However, the figures vary among regions; the mean for industrialized countries is around 3 400 kcal, and that for developing countries is around 2 500 kcal. Of course, average availability figures for a country mask very large differences among groups of the population.

To improve nutrition, agricultural planners should aim to expand the production of currently grown staple cereals and legumes and should promote consumption of fruits, vegetables, oilseeds and livestock products or those of small animal husbandry. Where land pressures are a constraint, particular attention should be given to maintaining a proper balance between crops and livestock.

Some countries that were major food importers in the 1960s, such as India, are virtually self-sufficient in cereal production (mainly rice and wheat). Yet in India undernutrition and malnutrition remain highly prevalent. Other countries, such as Indonesia, have become self-sufficient in rice production and have significantly reduced the prevalence of malnutrition. Some countries are far from being self-sufficient in food production yet have far less malnutrition than countries like India. For example, many Caribbean countries have very low levels of PEM, and many have emphasized sugar production for export and chosen to pay to import much of their food. However, it should be pointed out that in environments with risky markets, joint promotion of both food and cash crops is required to achieve food security.

Developing countries should strive for integrated rural development combining sustainable agricultural development and the promotion of off-farm economic activities. Expanding agricultural efforts to increase and improve food production as well as to increase the income of rural families through greater production of cash crops is the job of most ministries of agriculture in developing countries.

Agricultural research in universities or in research stations is important to agricultural efforts. A good agricultural extension service can help farmers increase their productivity and make decisions about their farm practices. Agricultural research and extension, leading to higher levels of agricultural production, can have a major impact on nutrition, especially if improved production makes it easier for the poor to consume an adequate diet. Many textbooks examine how agriculture and food production are used to improve food intakes and nutritional status. They are essential reading for those who are interested in these aspects.

Local seasonal factors are very important influences on food supply. For example, rainfall patterns can give marked variations in food production within a year and between years. Food production can also be influenced by other factors such as pests, prices, availability of agricultural inputs and farmers' ability to procure them, political stability and peace. Climatic variations, especially rainfall (or its lack) and inclement weather, can dead to annual variations in food production. These variations may bring about complex food storage and management requirements. Seasonally high food prices may be tied to costs of storage and failure to manage public food stocks adequately.

Food storage limits and post-harvest losses due to insects, pests, moulds, bruising, high temperatures, etc. can seriously destabilize food supply. Yet even after production, harvest and storage are successfully accomplished, other factors can affect food supply. These include commercial food processing and industrialization; food marketing, including transport; policies related to importation and exportation of food, including food donated in multilateral or bilateral agreements; and external assistance and debt repayment.

Access to food (food demand)

Access to food, or food demand, is influenced by economic issues, physical infrastructure and consumer preferences.

Per caput incomes and food prices are important determinants of food demand. Since the poor are the most vulnerable to food deficits and malnutrition, policies that increase their purchasing power will provide them with the potential to improve their nutrition. Therefore, increased employment and better wages become components of policies and programmes to improve nutrition. In many poor countries the minority of the working population are wage-earners and the majority are self-employed in agriculture. About 65 percent of the population in developing countries of Asia and Africa and about 35 percent in Latin America live in rural areas and rely on agriculture, fishing, animal production and forestry for food as well as for income to purchase food and other necessities. Assistance to help this group of poor farmers and rural workers increase their incomes and food productivity will have an effect similar to that of increasing the wages of the urban poor.

Food prices affect both supply and demand. Lower prices give farmers less revenue for their produce. If prices drop too low, farmers may not produce or sell at all. However, lower prices represent an increase in the purchasing power of the consumer. Lowering the price of a common staple food such as maize or rice is equivalent to raising the income of all those who purchase this food. Similarly, raising the price (a more common occurrence) is equivalent to lowering the income of those who purchase it.

Governments have various mechanisms at their disposal to help satisfy the needs of both producers and consumers. One of these is subsidizing food prices: the price paid to the farmer for a sack of maize or rice is raised while market prices for consumers are maintained, with the government paying for the difference between the two. Food price subsidies may be disastrous for the economy but politically expedient for the government. They may help the poor to improve their nutrition.

Too often in the past, pricing policies and subsidies have been directed at foods consumed mainly by high-income groups and have thus had no beneficial effect on vulnerable groups. For example, price restrictions on meat, powdered milk or tinned baby foods or subsidies on beef or margarine would hardly benefit the poor at all, nor would they have important nutritional impact. Structural adjustment programmes put in place to mitigate severe economic crises often adversely affect the poor, particularly in the urban areas, through increased food prices. However, in many countries the majority of the rural poor are food producers, and structural adjustments may benefit them by raising their income from the sale of food produced and providing incentives to improve production efforts. By limiting inflation and reducing other macroeconomic distortions, structural adjustment programmes may benefit all population groups.

Food demand is also affected by consumer preferences, which can be shaped by cultural beliefs and practices or intra-household food allocation. An efficient infrastructure, including roads, railways, bridges and marketing facilities, is a determinant of the extent and success of food distribution to different segments of society. In the developing world and also in some industrialized countries, families living near food markets have a steady and easy access to cheaper foods and a more diversified diet, while people living far from markets usually have a rather narrow range of foods to choose from.

Household food security

Household food security is the ability of the household to secure enough food to provide for all the nutrient requirements of all members of the household. It is critical to link national food security and household food security, because availability of food supplies in adequate quantity and variety is a necessary but insufficient condition for ensuring adequate access by all households in need. Furthermore, having adequate overall food supplies in households is a necessary but insufficient condition for ensuring nutritionally adequate consumption by all individuals within households. Clearly, the overall availability of food in a country, community or household is no guarantee of its equitable consumption.

Components of household food security

Household food security depends on a nutritionally adequate and safe food supply nationally, at the household level and for each individual; a fair degree of stability in the food availability to the household both during the year and from year to year; and access of each family member to sufficient food to meet nutritional requirements. (This last criterion includes not only physical access but also economic and social access to foods that are culturally acceptable.)

It is also important that the available food be both safe and of good quality. Attention to the food at every step of the food chain or food cycle is required to ensure its quality and safety. These steps include the cultivation of the food in the field (including protection against damage from pests or contamination with farm chemicals or pesticides); the harvesting, transport and storage of the food; processing and marketing; and finally the preparation and cooking of the food in the home and aspects of its consumption in the household. From the nutritionist's point of view, food losses and wastage along the chain are of great importance. However, important health concerns can also be raised if foods are not used correctly. An example is possible contamination, particularly from pesticides or other chemicals used to enhance production or to control pests such as insects, fungi, bacteria and viruses, or from natural toxins.

Food quality and safety are also affected by food hygiene, food handlers, people involved in food processing, those retailing the food and finally practices in the home. Certain codes and government inspections may help ensure some degree of safety, and education and knowledge of food hygiene by al] people will reduce the likelihood of contamination in the home. However, available facilities also influence food hygiene. Households that have poor facilities, no refrigeration, contaminated or inadequate water supplies or fuel shortages will find it more difficult to ensure food safety. See Chapter 33 for some ways to improve food safety and a discussion of food-borne diseases.

Another important aspect of food security is stability. The family or household must have the ability all year round to produce or procure the food its members require. The food must provide for all the family members' essential micronutrient and energy requirements, plus their wants, or desirable allowances, provided this does not lead to overconsumption. Of the greatest importance, especially when food or certain nutrients are available in marginal amounts, is proper distribution within the family to satisfy the special needs of children and females of childbearing age.

Incomes received from cash crops or wage earnings and prices paid for purchased items influence a rural population's food security. Inadequate landholdings, landlessness, sharecropping and other causes of poverty are all potent causes of family food insecurity. For the one-third of the population of developing countries who live in urban areas, much of the food obtained is purchased. The household food security of the urban poor depends on incomes, prices and the need to spend earnings on other essentials such as housing and transport. Their food security can be threatened by increased prices, job loss, income reduction, rent increases, larger numbers of dependent persons (more children, or relatives moving into the household) and other factors.

In both urban and rural areas the food must satisfy not only the energy needs but also the micronutrient needs of each household member. Therefore, the food consumed by each person must be varied and its quantity must be sufficient. If this is not the case, micronutrient deficiencies may occur.

Household food insecurity

Malnutrition may result from inadequate food, inadequate health or inadequate care (see Chapter 1). Inadequate food, be it due to food shortages or to inappropriate consumer behaviour or intrahousehold distribution, is termed food insecurity.

Food insecurity at the household or individual level may be transitory, or short-term, because of a particular event of short duration. In these circumstances it results from a temporarily limited access to food. Chronic food insecurity is long-term, may have a more marked impact and may be more difficult to control. The intensity of either short-term or long-term food insecurity is also important. Food insecurity occurs in mild, moderate and severe forms, just as PEM does. The level of food insecurity may be related to the relative availability of food.

A "shock" often precipitates household food insecurity. The shock can aggravate poverty (suddenly making a poor family very poor) or adversely influence food production (suddenly threatening farm food availability). There are many different kinds of shock, for example, serious illness, which may result in loss of income in an urban family or reduced agricultural production in a farm family; loss of a rural or urban job; farm production crises, such as failure of the rains; or a plague of locusts or some other agricultural catastrophe. Any crisis that has an adverse impact on the livelihood of the family may also result in household food insecurity.

Another important determinant of food insecurity is gender discrimination. Subordination of women in society, their overburdening and the greater difficulties faced by female-headed households contribute to food insecurity. Chapter 35 discusses ways to improve food security and reduce malnutrition in society.

Food policies in a development context

Clearly, development strategies and interventions pursued by developed and developing nations have an impact on nutrition. For this impact to be positive, developed and developing countries must decide what "development" really means.

Too often in the past, development has been associated with industrialization and measured by the productive capacity and the material output of a country. Indicators of development were gross national product (GNP) or mean per caput incomes. Economists tended to view improved nutrition and health as welfare questions. However, it is now clear that economic development does not benefit everyone equally. The poor have often been bypassed, and improvements in the quality of life of most low-income families in many countries have not kept pace with the improvements in national economic figures. The purpose and the intended beneficiaries of economic development should be examined before the interventions begin. If development plans do not encompass improved health and better nutrition for people, then their worth must be seriously questioned.

Nutrition-positive development projects are those that will benefit a large segment of the population, help reduce inequalities in income distribution and be likely to improve the nutrition, health and quality of life of those currently deprived. Labour-intensive projects are often preferable to capital-intensive ones, and support for small farmers may be more useful in regard to nutrition than assistance for large estates. Small farmers and especially women farmers are the most disadvantaged and require the most help. They are also the ones who receive the least assistance, in terms of both extension services and access to credit. In many countries, too little of the national budget is devoted to support for agriculture, which is essential for social and economic development and for nutritional well-being.

Food policy should make marketing as logical, simple and well-organized as possible, with a minimum involvement of intermediaries, to help ensure that the producer gets a fair return for his or her produce and that the consumer pays the lowest reasonable price for his or her food. Cooperatives are one form of marketing that may benefit both producer and consumer.

Recently, both adequate food and good nutrition have been declared basic human rights. As discussed in Chapter 1, good nutrition goes beyond food rights, including also adequate care and adequate health. It has been suggested that household food security should be examined as part and parcel of a broader food and nutrition system. Food factors included in the system are food production and some of the influences on it; the transport system; the market and its relationship to exchange and storage; and finally household food availability and access. Most "food systems" do not give consideration to the health causes of malnutrition such as infections including diarrhoea and intestinal worms. They also do not include caring factors that may influence nutritional status, such as breastfeeding, weaning and psycho-social stimulation. All of these factors are vital components of nutritional well-being. They are discussed in detail in other chapters of this book.

Chapter 3. Nutrition and infection, health and disease

The interaction or synergism of malnutrition and infection is the leading cause of morbidity and mortality in children in most countries in Africa, Asia and Latin America. Viral, bacterial and parasitic infections tend to be prevalent, and all can have a negative impact on the nutritional status of children and adults. The situation was similar in North America and Europe from about 1900 to 1925; common infectious diseases had an impact on nutrition and produced high case fatality rates.

The synergistic relationship between malnutrition and infectious diseases is now well accepted and has been conclusively demonstrated in animal experiments. The simultaneous presence of both malnutrition and infection results in an interaction that has more serious consequences for the host than the additive effect would be if the two worked independently. Infections make malnutrition worse and poor nutrition increases the severity of infectious diseases.

Effects of malnutrition on infection

The immune system

The human body has the ability to resist almost all types of organisms or toxins that tend to damage the tissues and organs. This capacity is called immunity. Much of the immunity is caused by a special immune system that forms antibodies and sensitized lymphocytes which attack and destroy the specific organisms or toxins. This type of immunity is called acquired immunity. An additional portion of the immunity results from the general processes of the body; this is called innate immunity

Innate immunity is due to:

There are two basic but closely allied types of acquired immunity. In one of these the body develops circulating antibodies, which are globulin molecules that are capable of attacking the invading agents and destroying them. This type of immunity is called humoral immunity. Antibodies circulate in the blood and may remain there for a long time, so that a second infection with the same organism is immediately controlled. This is the basis for some forms of immunization, which are designed to stimulate antibody production.

Questions and answers

Why are the case fatality rates from measles often 200 times higher in poor, developing countries than in the industrialized countries? The main reason is that the malnourished child is of ten overwhelmed by the infection, whereas the well-nourished child can combat it and survive.

Why do so many cases of kwashiorkor develop following an infectious disease and so many cases of nutritional marasmus following gastro-enteritis? It is well established that infections result in increased nitrogen loss and that diarrhoea reduces the absorption of nutrients from the intestinal tract.

The second type of acquired immunity is achieved through the formation of large numbers of highly specialized lymphocytes which are specifically sensitized against the invading foreign agents. These sensitized lymphocytes have the ability to attach to the foreign agents and to destroy them. This type of immunity is called cellular immunity. It is a highly complex system involving many different body organs (such as the spleen, thymus, lymph system and bone marrow) and also body fluids, particularly blood and its constituents and lymph.

The study of the complex system of immunity is termed immunology.

Effects of malnutrition on resistance to infection

A considerable amount of literature, documenting studies both in experimental animals and in people, demonstrates that dietary deficiency diseases may reduce the body's resistance to infections and adversely affect the immune system.

Some of the normal defence mechanisms of the body are impaired and do not function properly in the malnourished subject. For example, children with kwashiorkor were shown to be unable to form antibodies to either typhoid vaccine or diphtheria toxoid; their capacity to do so was restored after protein therapy. Similarly, children with protein malnutrition have an impaired antibody response to inoculation with yellow fever vaccine. An inhibition of the agglutinating response to cholera antigen has been reported in children with kwashiorkor and nutritional marasmus. These studies provide a fairly clear indication that the malnourished body has a reduced ability to defend itself against infection.

Another defence mechanism that has been studied in relation to nutrition is that of leucocytosis (increased production of white blood cells) and phagocytic activity (destruction of bacteria by white corpuscles). Children with kwashiorkor show a lower than normal leucocyte response in the presence of an infection. Perhaps of greater importance is the reduced phagocytic efficiency in malnourished subjects of the polymorphonuclear leucocytes that are part of the fight against invading bacteria. When malnutrition is present, these cells appear to have a defect in their intracellular bactericidal (bacteria-destroying) capacity.

Although malnourished children frequently have increased immunoglobulin levels (presumably related to concurrent infections), they also may have depressed cell-mediated immunity. In a recent study, the extent of this depression was directly related to the severity of the protein-energy malnutrition (PEM). Serum transferrin levels are also low in those with severe PEM, and they often take considerable time to return to normal even after proper dietary treatment.

A quite different kind of interaction of nutrition and infection is seen in the effect of some deficiency diseases on the integrity of the tissues. Reduction in the integrity of certain epithelial surfaces, notably the skin and mucous membranes, decreases resistance to invasion and makes an easy avenue of entry for pathogenic organisms. Examples of this effect are cheilosis and angular stomatitis in riboflavin deficiency, bleeding gums and capillary fragility in vitamin C deficiency, flaky-paint dermatosis and atrophic intestinal changes in severe protein deficiency and serious eye lesions in vitamin A deficiency.

Effects of infection on nutritional status

Infection affects nutritional status in several ways. Perhaps the most important of these is that bacterial and some other infections lead to an increased loss of nitrogen from the body. This repercussion was first demonstrated in serious infections such as typhoid fever, but it has subsequently been shown in much milder infections such as otitis media, tonsillitis, chicken pox and abscesses.

Nitrogen is lost by several mechanisms. The principal one is probably increased breakdown of tissue protein and mobilization of amino acids, especially from the muscles. The nitrogen is excreted in the urine and is evidence of a depletion of body protein from muscles.

Full recovery is dependent upon the restoration of these amino acids to the tissues once the infection is overcome. This requires increased intake of protein, above maintenance levels, in the post-infection period. In children whose diet is marginal in protein content, or those who are already protein depleted, growth will be retarded during and after infections. In developing countries, children from poor families suffer from many infections in quick succession during the post-weaning period, and they often have multiple infections.

Anorexia or loss of appetite is another factor in the relationship between infection and nutrition. Infections, especially if accompanied by a fever, often lead to loss of appetite and therefore to reduced food intake. Some infectious diseases commonly cause vomiting, with the same result. In many societies mothers and often medical attendants as well consider it desirable to withhold food or to place the child with an infection on a liquid diet. Such a diet may consist of rice water, very dilute soups, water alone or some other fluid with a low calorie density and usually deficient in protein and other essential nutrients. The old adage of "starve a fever" is of doubtful validity, and this practice may have serious consequences for the child whose nutritional status is already precarious.

The traditional treatment of diarrhoea in some communities is to prescribe a purgative or enema. The gastro-enteritis may already have resulted in reduced absorption of nutrients from food, and the treatment may further aggravate this situation.

These are all examples of how illnesses such as measles, upper respiratory infections and gastro-intestinal infections may contribute to the development of malnutrition. The relationship of intestinal parasites, diarrhoea and measles to nutrition is discussed below.

Parasitic infections

Parasitic infections, particularly intestinal helminthic infections, are extremely prevalent and are increasingly being shown to have an adverse effect on nutritional status, especially in those heavily infected. Hookworms (Ancylostoma duodenale and Necator americanus) infect over µ00 million people, mainly the poor in tropical and subtropical countries. They used to cause a prevalent debilitating disease in the southern United States. Hookworms cause intestinal blood loss, and although it appears that most of the protein in the lost blood is absorbed lower down in the intestinal tract, there is considerable loss of iron.

Hookworm disease is a major cause of iron deficiency anaemia in many countries. The extent of the loss of blood and iron in hookworm infections has been studied (Layrisse and Roche, 1966): daily faecal blood loss per hookworm (N. americanus) was reported to be 0.031 ± 0.015 ml. It was estimated that about 350 hookworms in the intestine cause a daily loss of 10 ml of blood, or 2 mg of iron. Infection densities much higher than this are not uncommon. In Venezuela, where much of this work was done, iron losses greater than 3 mg per day often resulted in anaemia in adult males, and losses of half this amount frequently produced anaemia in women of child-bearing age and in young children.

Worldwide, roundworm (Ascaris lumbricoides) is among the most prevalent of intestinal parasites. It is estimated that 1 200 million people in the world (one-quarter of the world's population) harbour roundworms. The roundworm is large (15 to 30 cm long), so its own metabolic needs must be considerable. High parasite densities, particularly in children, are common in environments where sanitation is poor. Complications of ascariasis can develop, including intestinal obstruction or the presence of worms in aberrant sites such as the common bile duct. In some countries ascarids are a cause of surgical emergencies in children, and many with obstruction die. In the majority of children, however, when malnutrition is prevalent, deworming improves child growth.

Trichuris trichiura or whipworm inhabits the large intestine and infects about 600 million people worldwide. The worms are small and, in heavily infected children, may cause diarrhoea and abdominal pain.

Many children living in poor sanitary conditions are infected with several parasitic infections at the same time. In areas where infection with these three parasites is common and where malnutrition is prevalent, deworming of children leads to an improvement in growth, a reduction in the extent of malnutrition and an increase in appetite. It also positively influences physical fitness and perhaps psychological development.

Bilharzia or schistosomiasis infections are prevalent in some countries. They also contribute to poor nutrition, poor appetite and poor growth. The three organisms that cause schistosomiasis (Schistosoma haematobium, Schistosoma mansoni and Schistosoma japonicum) are flukes, rather than ordinary worms.

Somewhat less is known about the relationship between intestinal protozoa! diseases and nutrition, but amoebas, causing serious dysentery and liver abscess, are highly pathogenic organisms, and infection with Giardia lamblia may cause malabsorption and abdominal pain.

The fish tapeworm (Diphyllobothrium latum) has an avidity for vitamin B12 and can deprive its host of this vitamin, with megaloblastic anaemia resulting. The fish tapeworm is common in people in only limited geographic areas, mainly in temperate areas and where undercooked fish is frequently consumed.

In many northern industrialized countries, farm animals and domestic pets such as dogs and cats are dewormed routinely. Much evidence suggests that pigs grow better when they regularly receive anthelmintics. Now that highly effective, relatively inexpensive and safe broad-spectrum anthelmintics such as albendazole and mebendazole are available, routine mass deworming should be introduced where parasitic infections are prevalent in humans and where PEM and anaemia are common. Similarly, routine efforts to treat children with schistosomiasis using metrifonate or praziquantel seem highly desirable both to rid children of potential serious pathology and to improve their nutritional status. More attention needs to be given to population-based chemotherapy for these infections along with intensification of public health and other measures to reduce their transmission, including improved sanitation and water supplies. Such efforts would improve the health and nutritional status of millions of the world's children.

Effects of diarrhoea

Many studies have indicated that gastrointestinal infections, and especially diarrhoea, are very important in precipitating serious PEM. Diarrhoea is common in, and often lethal to, the young child. In breastfed infants there is often some protection during the first months of life, so diarrhoea is often a feature of the weaning process. Weanling diarrhoea is extraordinarily prevalent in poor communities throughout the world, both in tropical and temperate zones. The organism responsible varies and often cannot be identified. Diarrhoea was a major cause of mortality in children in industrialized countries up to the beginning of the twentieth century.

Several studies have shown that admissions of cases of malnutrition are greatly increased during the season when diarrhoea is most common. For example, in a report from the Islamic Republic of Iran, more than twice as many cases of PEM were admitted in the warm summer than in the cold winter. The incidence of diarrhoeal disease followed the same pattern.

Hospital and community studies indicate that cases of xerophthalmia and keratomalacia are frequently precipitated by gastro-enteritis, as well as by other infectious diseases such as measles and chicken pox. Xerophthalmia is the major cause of blindness in several Asian countries; it is also prevalent in certain parts of Africa, Latin America and the Near East.

Intestinal parasites may contribute to diarrhoea and to poor vitamin A status. The exact mechanism of this relationship has not been proved, but it is likely that many infections reduce vitamin A absorption and that some result in decreased consumption of foods containing vitamin A and carotene.

Diarrhoea can be fatal, usually because it can lead to severe dehydration (see Chapter 37). Diarrhoea, and the complication of dehydration, may be said to be a form of malnutrition. Dehydration is a "deficiency" in the body of water and mineral electrolytes, and providing adequate quantities of these cures the deficiency. The term "fluid electrolyte malnutrition" (FEM) has been coined for this condition. Provision of water and adequate minerals in home-prepared food, breastfeeding or administration of oral rehydration fluids is now the accepted treatment. Although these are forms of therapy or treatment, they are really refeeding and replenishment. However, prevention requires measures and interventions to reduce infections, poverty and malnutrition. These are essential if countries are to reduce the incidence of diarrhoea.

Fatality rates for measles and other infectious diseases

A dramatic illustration of the effect of malnutrition on infection is seen in the fatality rates for common childhood diseases such as measles. Measles is a severe disease with a case fatality rate of about 15 percent in many poor countries because the young children who develop it have poor nutritional status, lowered resistance and poor health. In Mexico the fatality rate for measles has been reported to be 180 times higher than that in the United States; in Guatemala, 268 times higher; and in Ecuador, 480 times higher. The decline in case fatality rates of measles in North America, Europe and other industrialized countries has been dramatic over the last century.

Differences in the clinical severity and the fatality rates of measles in developed and developing countries are due not to differences in virus virulence but to differences in the hosts' nutritional status. For example, during a measles epidemic in the United Republic of Tanzania that was causing considerable mortality among the children of poorer families, it was observed that fatalities from the disease were extremely uncommon in the children of families of moderate income, such as those of hospital employees. Measles is also related to vitamin A deficiency. It has been shown that providing vitamin A supplements to children with measles who have poor vitamin A status greatly reduces case fatality rates.

Immunization against measles is proving very effective, and in many countries measles incidence has been markedly reduced.

Other common infectious diseases such as whooping cough, diarrhoea and upper respiratory infections also have much more serious consequences in malnourished children than in those who are well nourished. Mortality statistics from most developing countries show that such communicable diseases are the major causes of death. It was observed in several African countries at the end of the Sahel famine that very few children were dying of starvation or malnutrition, but that deaths from measles, respiratory infections and other infectious diseases were still very much above pre-famine levels. It is clear that many, perhaps the majority, of these deaths were due to malnutrition. This may seem a moot point for a grieving parent, but for the policy planner and the public health official it is important to know to what extent morbidity and mortality rates are due to or related to undernutrition.

An inter-American investigation of mortality in childhood showed that of 35 000 deaths of children under five years of age in ten countries, in 57 percent of the cases malnutrition was either the underlying or an associated cause of death. Nutritional deficiency was the most serious health problem uncovered, and it was frequently associated with common infectious diseases.

HIV infection and AIDS

Perhaps no disease has a more dramatic and obvious effect on nutritional status than acquired immunodeficiency syndrome (AIDS), the disease caused by the human immunodeficiency virus (HIV). In Uganda for many years the disease was called "slim disease" because extreme thinness was the main visible manifestation of the disease. Although the mechanisms by which AIDS leads to severe malnutrition have not been proven, there is no doubt that the disease and its associated opportunistic infections cause marked anorexia, diarrhoea and malabsorption as well as increased nitrogen losses. Some of the infections and conditions that are part of the AIDS complex of diseases were known to affect nutritional status long before the HIV virus was identified: tuberculosis has for many decades been associated with cachexia and weight loss, and malignancies such as sarcoma have long been known to result in wasting as they advance.

For a discussion of the relationship of AIDS to breastfeeding, see Chapter 7.

Chronic diseases and old age

There is a relationship between certain chronic diseases and immune response. It has also been clearly shown that in old age immunologic response is reduced, and undernutrition worsens this decline. The association of diabetes with infections is well known, and it is clear that in diabetes there is often impaired cellular response. Other diseases, for example several cancers, may also be related to lowered immune response (see Chapter 23).

Intervention studies

There have been relatively few well-controlled intervention studies to demonstrate either the effects of improved diets on infection or the nutritional effects of control of infectious diseases. Research in the village of Candelaria in Colombia showed that diarrhoea declined sharply as a result of supplementary feeding of children. A similar study in a Guatemalan village illustrated a significant decline in morbidity and mortality from certain common illnesses following the introduction of a nutritious daily supplement for preschool children.

A classic study conducted in Narangwal in the Punjab region of India demonstrated the value of combining nutritional care and health care in one programme. Children were divided into four groups. One group was given dietary supplements, one group was given health care, one group received both the supplements and the health care, and the fourth group served as control. As far as nutritional status and certain other health parameters were concerned, the combined treatment gave the best results. Nutritional supplementation alone also had a major impact. In comparison with the control group, there was no improvement in the nutritional status of the group that received only medical care but no dietary supplements.

Nutrition, infection and national development

Clearly, the effects of nutritional status on infections and of infections on malnutrition signify a very important relationship. The majority of children in most developing countries suffer from malnutrition at some time in their first five years of life. The problems of infection and malnutrition are closely interrelated, yet programmes to control communicable diseases and to improve nutrition tend to be introduced quite independently. It would be much more efficient and effective if the twin problems were attacked together.

Success in improving the health and reducing the mortality of children is dependent both on control of infectious diseases and on improvements in the children's food intake and care. There is increasing evidence to suggest that parents are more willing to control their family size when the chances are good that most children born will survive into adulthood. Consideration also needs to be given to providing a stimulating environment for the growing child.

The situation in the major industrial cities of Europe and North America a century ago was comparable to that in the poorest developing countries today. In New York City in the summer months of 1892, the infant mortality rate was 340 per 1 000, and diarrhoea. accounted for half these deaths. Improvements in nutrition, through the use of milk stations, for example, and a reduction in infectious disease served to lower these mortality rates by half in a period of less than 25 years. In the United Kingdom at the beginning of the twentieth century, rickets, combined with infectious diseases, took a heavy toll in the insanitary, smoky slums of the industrial cities, and measles was very often fatal among children of poor families, presumably because of poor nutrition.

Malnutrition and infections combine to pose an enormous hazard to the health of the majority of the world's population who live in poverty. This ever-present hazard particularly threatens children under five years of age. Many of the children who suffer from both malnutrition and a series of infections succumb and die. They are continually replaced in answer to parents' strong desire and often real need to have surviving children. The children who live beyond five years of age are not mainly those who have escaped malnutrition or infectious diseases, but those who have survived. Seldom are they left without the permanent sequelae or scars of their early health experiences. They are often retarded in their physical, psychological or behavioural development, and they may have other abnormalities that contribute to a less than optimal ability to function as adults and possibly to a shortened life expectation. Other factors influencing the development of these children include a lack of environmental stimulation and a host of other deprivations related to poverty.

The challenge to health workers, development economists, governments and international agencies is how best to reduce the morbidity, mortality and permanent sequelae that result from the synergism of malnutrition and infection. The politicians must be persuaded that attention to these problems is not only highly desirable but politically advantageous.

The control of infectious diseases and projects aimed at providing more and better food for people are fully justified and important components of a development plan. By themselves they may contribute to increased productivity and better lives. An improved infant or toddler mortality rate, a lowered disease incidence and a better-nourished population are probably better indicators of development shall national averages of telephones or automobiles per 1 000 families, or even than dollars or pesos per caput. Efforts for the control of infectious diseases and the improvement of nutrition both deserve a high priority in development plans and in international or bilateral assistance to low-income countries. They should be undertaken together because they will be mutually reinforcing and more economical if provided in a coordinated manner rather than separately. An allied issue is the need to provide a stimulating environment for the growing child.

Historical and epidemiological evidence suggests that reductions in infant and child mortality and improvements in health and nutritional status may be prerequisites to successful family planning efforts. Birth spacing deserves a high priority, especially where women are already overworked and undernurtured. Parents in all countries should receive assistance to help them achieve their desired family size.

Alarming as the situation of children's malnutrition and infection is, there is a general tendency to overlook the significance of these conditions in adults. Weakness, lethargy, absenteeism, poor productivity and stress can all have social and economic costs for individuals, families and communities.

There seems to be unassailable logic in recommending coordinated programmes that have three objectives: to control infectious disease, to improve nutrition and to make family planning services widely available. These three types of endeavour may themselves be synergistic.

Chapter 4. Social and cultural factors in nutrition

Social factors and cultural practices in most countries have a very great influence on what people eat, on how they prepare food, on their feeding practices and on the foods they prefer. Nonetheless, cultural food practices are very rarely the main, or even an important, cause of malnutrition. On the contrary, many practices are specifically designed to protect and promote health; providing women with rich, energy-dense foods during the first months following childbirth is an example. It is true, however, that some traditional food practices and taboos in some societies may contribute to nutritional deficiencies among particular groups of the population. Nutritionists need to have a knowledge of the food habits and practices of the communities in which they work so that they can help to reinforce the positive habits as well as strive to change any negative ones.

Food habits and their origins

All people have their likes and dislikes and their beliefs about food, and many people are conservative in their food habits. They tend to like what their mothers cooked for them when they were young, the foods that are served on festive occasions or those eaten with friends and family away from home during their childhood. The foods that adults ate without a second thought in childhood are seldom totally disagreeable to them in later life.

What one society regards as normal or even highly desirable, however, another society may consider revolting or totally inedible. Animal milk is commonly consumed and liked by many people in Asia, Africa, Europe and the Americas, but in China it is rarely taken. Lobsters, crabs and shrimps are considered delicacies and prized foods by many people in Europe and North America, but are revolting to many people in Africa and Asia, especially those who live far from the sea. The French eat horse meat; the English generally do not. Many people will delightedly consume the flesh of monkeys, snakes, dogs and rats or will eat certain insects, yet many others find these foods most unappealing. Religion may have an important role in forbidding the consumption of certain foods. For example, neither the Muslim nor the Jewish peoples consume pork, and Hindus do not eat beef and are frequently vegetarians.

Food habits differ most widely in regard to which foods of animal origin are liked, disliked, eaten or not eaten in a society. The foods in question comprise many of those that are rich in good-quality protein and that contain haem iron, both of which are important nutrients. People who do not consume these foods are deprived of the opportunity of obtaining these nutrients easily. On the other hand, those who overconsume animal flesh, some seafoods, eggs and other foods of animal origin will have undesirable amounts of saturated fat and cholesterol in the diet. Balanced consumption is the key.

Relatively few people or societies have strong negative feelings about consuming cereals, roots, legumes, vegetables or fruit. They may have strong preferences and likes, but most maize-eating people are also willing to eat rice, and most rice-eating people will eat wheat products.

It is often stated that food habits seldom or never change and are difficult to change. This is not true; in many countries the current staple foods are not the same as those eaten even a century ago. Food habits and customs do change, and they are influenced in many different ways. Maize and cassava are not indigenous to Africa, yet they are now major food staples in many African countries. Potatoes originated in the Americas and later became an important food in Ireland.

Food preferences are not made and abolished by whims and fancies, of course. More often the adjustments are generated by social and economic changes that take place throughout the community or society. The issue is often not what foods are eaten but rather how much of each food is eaten and how the consumption is distributed within the society or within the family.

The tendency of many wage-earners to spend almost all their wages within a few days of receiving them often results in a family diet of varying nutritive value. The family eats much better just after one payday than just before the next. Wages are often paid monthly, and there seems little doubt that a change to weekly payment of wages would improve the diet of wage-earners and their families.

The person who controls the family finances influences (intentionally or unintentionally) both the family diet and the food fed to children. In general, when mothers, rather than just fathers, have some control over finances, the family diet is likely to be better. When the mother has little control over family funds, dietary arrangements may become haphazard or even dangerous.

Nutrition education has been an important influence on food habits, and not always a positive one. Fortunately, the days are long gone when nutritionists promoted costly protein-rich foods to eople who couldn't possibly afford them. Unfortunately, the tendency to single out foods or nutrients either to promote or to prohibit has not yet gone, nor has the tendency to try to teach by creating fear and taking the enjoyment out of eating. However, change always comes slowly and old habits die hard; people who were taught in these old ways are still responsible for feeding themselves and their families, and they may find it hard to change again.

Nutritional advantages of traditional food habits

The traditional diets of most societies in developing countries are good. Usually only minor changes are needed to enable them to satisfy the nutrient requirements of all members of the family. Although the quantity of food eaten is a more common problem than the quality, this chapter focuses on types of food and eating habits.

Eating certain protein-rich foods such as insects, snakes, baboons, mongooses, dogs, cats, unusual seafoods and snails is definitely beneficial. Another habit that is good nutritionally is the consumption of animal blood. Some African tribes puncture the vein of a cow, draw off a calabash of blood, arrest the bleeding and consume the blood, usually after mixing it with milk. Blood is a rich food, and mixed with milk it is highly nutritious.

A custom frequently found among pastoral and other peoples is the drinking of soured or curdled milk, rather than fresh. The souring of milk has little effect on its nutritive value but often substantially reduces the number of pathogenic organisms present. In communities where milking is not hygienically performed and where the containers into which the milk goes are likely to be contaminated, it is safer to drink sour rather than fresh milk. Boiled milk would be safer still.

Many societies, for example in Indonesia and in parts of Africa, partly ferment foods before consumption. Fermentation may both improve the nutritional quality and reduce bacterial contamination of the food.

The traditional use of certain dark green leaves among rural peoples is another beneficial practice and should be encouraged. These leaves are rich sources of carotene, ascorbic acid, iron and calcium; they also contain useful quantities of protein. Non-cultivated or wild dark green leaves such as amaranth leaves as well as those from cultivated food crops such as pumpkin, sweet potato and cassava are much richer in vitamins than pale, leafy vegetables of European origin such as cabbage and lettuce. Well-meaning expatriate horticulturists in Africa have too often tried to get villagers to cultivate such European vegetables rather shall their traditional vegetables.

Many wild fruits are rich in vitamin C; an example is the pulp within the pod of the frequently consumed baobab.

Traditional grain preparation methods produce a more nutritious product than does elaborate machine milling.

Some communities sprout legume seeds prior to cooking, which enhances their nutritive value, as does the soaking of whole-grain cereals before their processing into local beers and some non-alcoholic beverages. These seeds and grains usually have a high vitamin B content. Finally, it cannot be stressed too strongly that the traditional method of infant feeding- from the breast - is nutritionally far superior to bottle-feeding (see Chapter 7).

Food taboos

A number of food habits and practices are poor from a nutritional point of view. Some practices result from traditional views about food that are liable to change under the influence of neighbouring peoples, travel, education, etc. Other food practices are governed by definite taboos.

A taboo may be followed by a whole national group or tribe, by part of a tribe or by certain groups in the society. Within the society, different food customs may be practiced only by women or children, or by pregnant women or female children. In certain cases traditional food customs are practiced by a particular age group, and in other instances a taboo may be linked with an occupation such as hunting. At other times or in other individuals a taboo may be imposed because of some particular event such as an illness or an initiation ceremony.

Although these matters border on the realm of anthropology, it is important for a nutritionist to be familiar with the food customs of people in order to be able to improve their nutritional status through nutrition education or other means. Moreover, it is evident that anthropology and sociology are important to the nutrition worker who is either investigating or trying to improve the nutritional status of any community.

Some customs and taboos have known origins, and many are logical, although the original reasons may no longer be known. The custom may have become part of the religion of the people involved. For example, the Jewish taboo against pork was probably introduced to eliminate the prevalent pork tapeworm, which was thought to be sapping the strength of the Jewish people. Even though 2 000 years later it is now possible to eat pork safely, Jews still do not eat pork. Muslims share this view about pork. In neither case is this a nutritionally damaging taboo.

Many taboos concern the consumption of protein-rich animal foods, often by those groups of the community most in need of protein. A common taboo in Africa against the consumption of eggs is rapidly disappearing. This taboo usually applies to females, who are said to become sterile if they eat eggs. The psychological connection between human fertility and the egg is obvious. In other places the custom applies to children, perhaps to discourage them from stealing the eggs of setting hens, which would endanger the survival of poultry. Other customs, again often affecting women and children, concern fish. These customs may amount to a full taboo, although people not used to fish often dislike it merely because they find its smell distasteful or its appearance "snake-like". Many cultures have strong views about the consumption of milk or milk products.

The customs that prohibit consumption of certain nutritionally valuable foods may not have an important overall nutritional impact, particularly if only one or two food items are affected. Some societies, however, forbid such a wide range of foods to women during pregnancy that it is difficult for them to obtain a balanced diet.

Many of the nutritionally undesirable taboos that existed a quarter of a century ago have weakened or disappeared as a result of education, mixing of people from different societies and travel. Of those that remain, some food habits may seem illogical and their origins obscure, but it is not advisable for outsiders to try to alter ancient food habits without looking very closely into their origins. Moreover, it makes no sense to attempt to alter a habit that does not negatively affect nutritional status.

Nutritionally bad habits, like all other habits, are best changed by the people who have them. In this regard, influential local people, with the welfare of their fellows at heart, may join nutritionists and become part of an important alliance pledged to eradicating malnutrition. A speech by the president or a cabinet minister, the sight of a respected tribe leader eating some forbidden food and coming to no harm or the return to the village of educated and enlightened local people will prove much more effective than the preaching or goading of an outsider.

Changing food habits

In some parts of the world the staple foods are changing or have changed. Maize, cassava and potatoes, now grown in large amounts in Africa, originated outside the continent. Since none of these foods were eaten in Africa a few hundred years ago, it is clear that the food habits of millions of people have changed. Vast numbers of people in Africa have abandoned yams and millet for maize and cassava, just as many in Europe abandoned oats, barley and rye for wheat and potatoes. Food habits are still changing rapidly. The difficulty, of course, lies in trying to guide and foster desirable changes and to slow down undesirable ones.

It is often difficult to fathom what factors have been most important in stimulating or influencing changes in food habits. The rapid increase in bread consumption in many African, Latin American and Asian countries where wheat is not the staple food is understandable. It is at least in part a labour-saving phenomenon; bread is one of the first "convenience" foods to have become available. Before leaving home to go to work one can eat some slices of bread instead of the traditional breakfast of porridge, which requires preparation time and is unpleasant cold. Bread can be carried in the pocket and eaten during a break in the working day, or when travelling.

In most of the world the traditional main staple food has remained constant, irrespective of urbanization, modernization or even westernization. Thus in much of Asia rice remains the preferred staple food in rural and urban areas. Some people in Africa, such as the Buganda in Uganda and the Wachagga in the United Republic of Tanzania, continue to have a preference for plantains as their staple food. Maize based products such as tortillas remain important in the diets of most Mexicans and many in Central America.

Changes in food habits are not just accidental, of course; they can be deliberately initiated. At community and family level, school-age children can be important agents for change. They are still forming their tastes and developing their preferences. If they are introduced to a new food they will often readily accept it and like it. School meals may usefully introduce new foods to children and thus influence food habits. This widening of food experience in childhood is extremely important. Children may influence the immediate family and later their own children to eat new, highly nutritious foods.

Harmful new habits

Not all change is desirable, of course, and not all new food habits are good. Chapter 7 describes in detail the harmful effects of the rapid spread of bottle-feeding using infant formula or animal milk in place of breastfeeding. This is an undesirable, relatively new food trend. Less attention has been given to the question of other baby foods that have been marketed and much promoted and advertised in developing countries. Locally available complementary or weaning foods, home-produced and traditionally fed, are often as or more nutritious than the manufactured baby foods, and then are always much cheaper. They are usually introduced gradually while breastfeeding continues well into the second year and beyond. Manufactured baby foods should only be promoted to those who are unable or unwilling to continue breastfeeding. They are safe and nutritionally adequate when prepared hygienically and in the right dilution. They are convenient for those who can afford to purchase them. However, such manufactured foods are expensive compared with local foods, and for most families in developing countries, other than the very affluent, they may be a waste of money. For families who already have too little money to spend on food and other essentials, these foods are a very expensive way of buying the nutrients that they are advertised to contain.

Another particularly misleading type of advertising relates to the glucose products said to provide "instant energy". Energy is present in large amounts in nearly all the cheapest foods. Similarly, drinks advertised as "rich in vitamin C" are usually unnecessary, since few children suffer from vitamin C deficiency. Vitamin C can be obtained just as well from fruits such as guavas, mangoes and citrus, or from a range of vegetables.

The so-called protein-rich weaning foods are also much advertised. These arc nutritionally good products, but they cost much more shall protein-rich foods available in the market such as beaus, groundnuts or dried fish, meat, eggs or milk. It usually costs much more to provide 100 g of protein from these commercially advertised products than, for example, from beans bought in the local market. The essential question is how a mother could best improve her child's diet if she had a little extra to spend. The answer would seldom be a manufactured baby food.

In some countries the staple food has remained unaltered, but the form in which it is preferred may have changed over the years. As described in Chapter 16, the rapid spread and popularity of highly milled rice in Asia had disastrous consequences and led to a high prevalence of beriberi, with much morbidity and many deaths. In many parts of the world highly milled cereals have replaced traditionally lightly milled and more nutritious wheat, rice and maize. In the United Kingdom and the Russian Federation, white bread has replaced brown or whole-grain breads, and in East Africa highly milled maize meal is often purchased and has replaced lightly milled maize flour. Urbanization, modernization and sophistication have often led to diets in which a greater percentage of energy intake comes from sugar and fats, and to increased consumption of salt. All Of these are generally undesirable changes from a nutritional standpoint.

Influencing change for the better

What can health workers or nutritionists in a community do about food habits, old and new? They can:

Chapter 38 describes the use of social marketing and other well-tested nutrition education techniques that can help achieve some of these objectives.

Chapter 5. Population, food, nutrition and family planning

Many thinkers in the world and many who work in the development field believe that the world's population size and increase is its greatest problem and humanity's gravest threat. Clearly the ratio of the number of people to the amount of food available has an impact on nutrition, but how are the two caused to interact? Late in the eighteenth century the British political economist Thomas Malthus grimly speculated that population growth could soon outstrip food production and supply. Close to the end of the twentieth century this has not yet happened, but malnutrition is widespread.

Many books and journal articles address the enormously important questions of population, demography and family planning. These texts should be consulted by readers wishing to understand population issues in their entirety. This chapter briefly discusses some aspects of fertility and family planning as they relate to nutrition, and observes their importance for the world and particularly for the developing countries, where most population growth is taking place.

Population growth

World population is increasing at an alarming rate. Unless the rate of increase is slowed down in the next few decades, the world will face extremely serious problems. Figure 1 illustrates the rate of population increase over the last 2 000 years. The world population was around 250 million people 2 000 years ago. After taking 16 centuries to double to 500 million, it then doubled in two and a half centuries to reach ] 000 million in 1850, and it doubled again in one century to reach 2 000 million people in 1950. Now the population of the world is doubling every 35 years; it reached 5 000 million before 1990.

Population pressure is most marked and is having a major impact in Asian countries such as Bangladesh, India and Pakistan. China has the largest population, but its government now manages to ensure that its people are reasonably fed. It has also recently managed to prevent any large increase in population.

FIGURE 1. Growth of world population

Africa as a whole may not be overpopulated at present, but population density is putting pressure on land distribution in certain areas. In Kenya the population is increasing at about 3 percent per year. At this rate - among the highest in the world - the population will double in 25 years. The country may well have sufficient land, food-producing capacity and other resources to meet the demands of double or triple the present number of people. However, doubling food production is not enough. Kenya must also double the number of schools or school places, of hospitals or hospital beds, of houses and of all services in the 25 years that it will take for the population to double. Even then it will only have maintained the current level of development.

Each government must take its own decisions concerning population policy, but all governments must be aware that, if the nutritional status of people is to improve, the availability of food and services must increase more rapidly than the population.

Clearly when the number of people in a country, a community or a family increases, its food needs also increase. However, food availability is influenced by more shall population size. Economics, politics and geography are factors, too. Hong Kong and the Netherlands are both densely populated, yet they have little hunger and their infant and child mortality rates are low.

In most developing countries - even the poorest - in Africa, Asia and Latin America, infant and young child mortality rates have declined markedly in the past 30 years. When women continued to have the same number of babies and fewer died, family size increased.

In some countries, increased family size has also resulted from narrower spacing between pregnancies (partly because of a shorter duration of exclusive or nearly exclusive breastfeeding, as discussed in Chapter 7), younger age at first pregnancy and lack of knowledge about, or lack of availability of, family planning services. It is generally agreed that when the mother or the parents have confidence that most children born are likely to survive into adulthood, they are much more likely to consider and practice birth control.

Many of the more prosperous countries, particularly in Europe, have reached the stage of zero population growth, excluding growth from immigration. This means that the number of births per year nearly equals the number of deaths. In contrast, many developing countries have far more births than deaths and, consequently, rapidly increasing populations. However, several poor countries have reduced their rate of population increase, mainly through family planning methods.

Urbanization

Overall population growth is not the only demographic concern of many developing countries. The rapid increase in the percentage of people living in large cities is also a growing worry.

Population in urban areas has increased in part because of increased fertility rates, but migration from the rural areas to the cities is also a major cause. City dwellers in general are consumers, not producers, of food; as they become more numerous relative to the rural residents, the food production burden on the few becomes greater. In 1900 there were only four cities