Nutrition and Disease

R. J. Jarrett

• Publisher: Routledge
• Year: 2022
• Print ISBN:
  9781032244389
• eBook ISBN:
  9781000567038
• Topic: Medicine
• Subtopic: Health Care Delivery

Originally published in 1979, this book presents a coherent body of information on the inter-relation between nutrition, health and disease in its social context. The first section deals with undernutrition. The socio-cultural and economic factors underlying the deficiency diseases are discussed as well as the diseases themselves and the precise role of nutrition in their genesis. The problems of abundance are largely those of obesity, atherosclerosis, hypertension, diabetes and cancer and these are the main topics considered in Chapter 2. This chapter also discusses and evaluates the evidence for incriminating fibre deficiency in certain conditions. The final chapter gives accounts of the links between the immune defence system and nutrition.

1 THE PROBLEMS OF UNDERNUTRITION

G.J. Ebrahim

Introduction

Man needs food to provide energy for the body’s essential physiological functions like respiration, circulation, metabolism and so on, for maintaining body temperature, for the growth and repair of the body’s tissues, and for obtaining essential nutrients for the several biochemical processes essential in body metabolism. The food that he eats is vegetable or animal in origin, and in both forms the energy which it provides is basically solar energy which has been ‘trapped’ by photosynthesis and stored in various organs of the plant. Man, in common with other species of the animal kingdom, obtains this energy either by consuming these parts of the plant, e.g. cereal or tuber, or secondarily by consuming animals or their products who live on plants.

In common with all living organisms, man obtains food by interaction with his environment. Prior to the development of agriculture man was a hunter-gatherer and ate what his environment provided. Several tribes in Africa, the aborigines of Australia and the Eskimo are still by and large in this stage of development and their means of obtaining food from the environment can be described by the model in Figure 1.1 below. With the beginning of agriculture, man evolved agricultural technology, social systems and cultural practices to enable him to interact with his environment singly or in groups in order to obtain a regular supply of food. Commerce and marketing has also been part of this development and in recent years this aspect of food production has grown into ‘agribusiness’ which is concerned with the processing, sale and marketing of foods in different forms on national and even global scales. This aspect of man’s interaction with his environment is demonstrated by the model in Figure 1.2.

Figure 1.1: Obtaining Nutrients from the Environment — the Hunter-Gatherer Stage

Figure 1.2: Obtaining Nutrients from the Environment — the Complex Society

From the beginning of the practice of agriculture, there has been a tendency to concentrate on those species of plants that are most productive and rewarding in terms of labour (and capital) invested. In the past few centuries this trend has accelerated, especially with the coming of industrialisation and the development of cash economies. The supermarkets and convenience foods have further restricted choice in diets in urban industrial societies and through the development of multinational corporations are exerting their influence on Third World countries as well. This trend for more and more people to be nourished by fewer varieties of plants has reached the stage where a large proportion of the world’s population is dependent on a handful of plant species. Four crops — wheat, rice, maize and potato — together constitute more than all the other food crops put together. Figures 1.3, Figures 1.4 and 1.5 show the main parts of the world where the common food crops are raised.

Figure 1.3: Principal Sources of Maize

Figure 1.4: Principal Sources of Wheat

Figure 1.5: Principal Sources of Rice

The forms in which we know many foods today may be totally different from their progenitors. Wheat is a good example. Three kinds of wheat were originally domesticated from wild grasses. All three are obsolete and hardly grown today. One of these, called emmer, was the dominant wheat for several millennia and is still grown on an appreciable scale in Ethiopia and parts of south India. Emmer was the wheat of Egypt at the time of Alexander’s conquest of that country in the 4th century BC and was replaced by bread wheat. The type of wheat grown today does not belong to any of these three early varieties. It is thought that a mutated form of emmer is the ancestor of the common ‘macaroni wheat’ and that hybridisation with a wild goat grass gave rise to a form of wheat which was suited to the dry steppes of the world. Besides the selection that occurs in nature, as illustrated by the example of wheat, man also intervenes by a deliberate process of selection, e.g. by his taste for glutinous or non-glutinous, long-grained or short-grained rice and so on. It is now possible to accelerate the processes of hybridisation and selection as well as to channel them in any desired direction because of the growth in the science of plant genetics.

History has also intervened in several instances to bring about the spread of various crops. For example, potato was restricted to the Andean Highlands of South America until the sixteenth century when it was introduced to Europe. After a few decades of acclimatisation it emerged in a form suitable for the climatic conditions of Europe and eventually became a staple food. Sugar cane was indigenous to Asia and was introduced all around the Mediterranean by the Arabs in the ninth century. Christopher Columbus took specimens with him on his second voyage to the Antilles in 1493 and the following year it reached Hispaniola and Cuba. By the early sixteenth century it was widely consumed, with sugar refineries established in Europe and a lucrative trade across the Atlantic. Cottonseed as a major source of edible oil is a development of this century and it is now widely used as a ‘filler’ oil in many powdered milks for infant feeding.

The dominance of a crop in any particular region is a result of a number of ecological factors. The soil, the environmental temperature, rainfall and number of hours of sunlight will determine which crop will grow best. Socio-cultural and economic factors also depend on these. The farmer tends to concentrate his labour on a proven low-risk crop and to minimise diversity, but this also has its problems, because the farmer and his family will be restricted to one predominant source of nutrients and run the risk of deficiencies.

Systems Through Which Man Interacts with Environment to Obtain Food

As human society has evolved and the knowledge of agriculture and farming has increased, man has evolved increasingly complex systems through which land can be worked and food obtained and processed for use. At one end of the spectrum is the traditional farming system, characteristic of the peasant societies of the Third World. Such a system involves only man, his animals, his seed and his land, with very little involvement of industry, government or commercial and other agencies. In such a system productivity of the land is limited by the fertility of the soil and the climate, and the family income largely depends on the amount of land that can be worked with family labour. At the other end of the spectrum is the mechanised farm which forms part of the ‘agribusiness’, producing large crop surpluses. To compare outputs in the two systems, the average Indian or Pakistani farmer harvests little more than one metric ton of rice or wheat per hectare against 6 metric tons in the USA.

Agricultural Technology

Many of the farming systems of the developing world use a minimum of technology. Human muscle or draught animals provide the force for working the land. External inputs in the forms of machines, fuels and fertilisers are minimal or non-existent. The fertility of the soil is a limiting factor in output, particularly with regard to the nitrogen content, in which tropical soils tend to be deficient. The local varieties of grain grown are particularly suited to the environment, having been bred over a period of thousands of years, though the output is low. The traditional systems represent a type of ecological equilibrium which can be sustained indefinitely, given the available resources and provided that population growth is kept within the capacity of the system. On the other hand modernisation in agriculture needs heavy inputs in the form of energy, fertilisers, irrigation and high maintenance and research costs.

Much of agriculture in the Third World is rain-dependent. In a system where, because of low production, the margin of safety is low, a deficiency of even 25 per cent in rainfall can lead to crop failure of sufficient intensity to give rise to a threat of famine. In many parts of Asia and Africa such a deficiency in rainfall occurs on average once in five years.

Extension programmes specifically developed to help the small land holders and involving minimal capital expenditure are necessary to improve agricultural outputs in the developing world. The ‘gardening’ system of agriculture, like intercropping (more than one crop in the field), multiple cropping (several crops in succession in a year), relay planting (sowing a second crop between the rows of an earlier maturing crop), together with composting and irrigation through wells, need to be developed in order to improve food production in regions which suffer from chronic hunger.

Social Systems

Besides agricultural technology, social systems determine the amount of food available to an individual and his family. Inadequate nutrition has often been desribed as a social disease and in countries where malnutrition is common, its causes include factors inherent in the very nature of the society. Similarly, in countries where malnutrition has been overcome rapidly, political improvements have been major contributory factors.

In the typical developing country 50 to 80 per cent of the population is rural. The source of livelihood is the production of food or fibre crops or animal husbandry. The productivity of land is abysmally low; furthermore the ratio of land to population is dwindling. Thus in India the average size of a holding is 7.5 acres, but about 70 per cent of all holdings are below this average. Twenty-two per cent of rural families own no land at all and 47 per cent own less than an acre. The land tenure system in many countries favours the big landlord who employs farm labour at low wages. In one study of rural poverty in India it was found that 40 per cent of the rural population had an annual per capita consumer expenditure below the estimated breadline.

The rural poor have limited access to health care and education. Housing is substandard and life expectancy is low. Many are tied to a life of drudgery, eking out an existence on meagre land resources. In many such traditional agricultural systems almost half the energy derived by people and animals from the photosynthetic product of plants is expended to grow and prepare food, leaving little margin for anything else.

At the international level, the social system also tends to favour the rich. Many countries in Africa and Asia are former colonies in which the best land was principally utilised for the production of cash crops. Fifty-five per cent of crop land in the Philippines and over 80 per cent in Mauritius is assigned to cash crops. Moreover the thrust of agricultural research was also towards cash crops and local food crops were neglected. There are numerous centres for research on coffee, cocoa, oil palm, jute, rubber and cotton, but few for wheat, rice, maize and legumes. In more recent times the inequality of the international social system has taken yet another turn. The rising affluence of the industrialised nations has brought about a change in eating habits, causing an increased demand for meat and dairy products. This in turn has led to an increased demand for grain as cattle feed. In North America the per capita consumption of grain is about 1000 kg per year; of this, only about 75 kg are used directly as human food, much of the remainder being fed to animals. By contrast, cereal consumption in the Third World is about 200 kg per yea...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Original Title Page
• Original Copyright Page
• Table of Contents
• Preface
• Introduction
• 1. The Problems of Undernutrition G.J. Ebrahim
• 2. The Problems of Food Abundance R.J. Jarrett
• 3. Nutrition and Immunity R.N. Poston
• Notes on Contributors
• Index