INTRODUCTION AND HISTORICAL PERSPECTIVE ON NUTRITION

Introduction

Human Nutrition touches on virtually every aspect of human endeavor, as it is of central importance to health. Where studies have been carried out (and observations made), it has been found that differences in growth and well-bring often result from diets consumed. When a man is in good health, nutritionally, he feels good. He has vitality (he does not tire easily) and he is healthy. He is emotionally stable and enthusiastic about life. When one is well-nourished, it reflects in one’s appearance and behaviour. Generally, his posture is good; his muscles are firm, with only a small amount of fat covering. His complexion is clear, and his eyes sparkle and he is intelligent.

On the other hand, when one is undernourished, he is inclined to tire easily (he lacks stamina), to be irritable and to get easily anxious. In general, such people are much more susceptible to illness. Such people frequently are unaware of the fact that poor eating habits may be the root of their difficulties. Furthermore, there are long-term effects of such habits on their lifespan and productivity. Within a nation, the long term effect of poor nutrition may reflect in the overall height, weight, productivity and longevity of the nationals. As one can observe, even at the community level, the children of the rich most often look better and do better in life than the children of the poor whose poverty is often reflected in what they eat. The children of the rich usually grow faster and taller than the children of the poor. Also, urban dwellers, who do less work, on account of their exposure to modern facilities, are most usually more attractive, fatter and more robust than their rural counterparts, who do not enjoy these facilities. The latter often age prematurely.

If man must succeed in his quest to overcome the problem of hunger, he should start by taking a retrospective view of his past as a guide for the future. An author once remarked,

“what little we know, what little power we possess, we owe to the accumulated endeavors of our ancestors.”

The oldest human records indicate that there was an awareness of the relationship between what we eat and what we are – and that food supplies the energy of life, becomes a part of us as well as change us. Indeed, it takes little science to learn that we feel good when we eat and bad when we go hungry. Man also learnt early to know that those who have plenty of food are likely to have fewer episodes of sickness. Furthermore, man learnt which foods can be consumed and which ones are poisonous. For example, our local people know which mushrooms can be eaten, and which ones are not to be eaten. However, if one knows that certain potato tuber is safe and nourishing, he might not be able to tell if the potato leaves are poisonous. Thus, such knowledge is valuable for human existence, but it may not provide the basic understanding of how foods function. Yet the primitive people endowed foods with magical powers and believed that qualities of the food could be transmitted to the eater. This is why certain primitive people believed, for example, that if they ate the genitals of the hunted animals they would become more sexually potent. Others believed that if their pregnant women ate certain animal foods, they would bear children who would resemble these animals.

• Historical Perspectives

More than 10,000 years ago, before agriculture came into existence, man lived in a hunting-gathering society. He survived mostly on fruits, vegetables and nuts, and very little or no animal foods. Today most of the few remaining hunting-gathering societies left in the world still live largely on vegetables and fruits, with little animal foods. Among the Kung Bushmen of Northern Botswana, for example, there is very little contact with modern civilization. In this hunting-gathering society, hardly can one find an obese individual among the people. Indeed, they tend to be undernourished and energy-deficient particularly at the end of the dry season. Their infants do not experience malnutrition as they are breast-fed exclusively. Their adults, too, hardly experience malnutrition except after illness or injury. Due to the lack of salt in the diet of the Bushmen, age-dependent hypertension and high blood pressure are nonexistent, unlike in civilized societies. Their plasma cholesterol levels are also very low, averaging 120 mg per ml. Their supply of meat is intermittent. Their animal protein sources, chiefly from wild buck and small wild animals such as hare, have little fat (which are predominantly PUFA) in their muscles. They depend mainly on vegetable foods, which account for more than half of their food energy, and are mainly mangongo nuts, rich in linoleic acid. Dental caries do not occur among them, as sugar consumption is nil. Their only sugar source is an occasional wild honey. The main causes of death, especially among the younger population are infections and accidents. They often walk long distances, with heavy loads. Their numbers are often small and stable. Thus, modern nutrition must therefore take off from these reference points.

Until the birth of writing, some 3,300 B.C., by the Sumerians of the Fertile Crescent, there had been no records of drugs and their corresponding ailments, or even the location of symptoms. The Egyptian hieroglyphics which came a little later, established these records. By the 4th century, what we may now regard as scientific medicine had begun in Ionia on the island of Cos. In these early periods, physicians were the nutritionists. For example, Hippocrates (460-364 B.C.), known as the “Father of Medicine” advanced the idea that sickness is best understood if one considered the whole patient and his environment and that successful treatment could be expected only if one used the beneficial experience of similar cases. But scientific experimentation was not the way of Greek philosophers, including Hippocrates; rather, it was logic. Hippocrates, in his typical Greek manner of logical reasoning, propounded some beliefs and made some remarkable observations which later researches depended on till today. For example, Hippocrates aphoristically believed, even at that early period, that“persons who are naturally very fat are apt to die earlier than those who are slender.”

He also noted that“growing bodies have the most innate heat; they therefore require the most food, for otherwise, their bodies are wasted. In old persons, the heat is feeble and therefore,they require little fuel, as it were, to the flame, for it would be extinguished by much….”

Hippocrates was said to have paid strict attention to the diet of his patients as a feature of his therapeutic regimens. In spite of the fact that Hippocrates was very much concerned with the diet of his patients, nutrition writers and physicians of his day usually paid very little attention to nutrition concerns and the uses of food in medical treatment. Furthermore, the anecdotal observations of Hippocrates were not given much regard in scientific circles. Indeed, from his writings, it was obvious that foods were to him what one can now categorize as items of pharmacology. Thus, in spite of his concern for the therapeutic nature of foods, Hippocrates was not to be regarded as the Father of Nutrition. It is indeed clear to modern nutritionists that Hippocrates had little understanding of the nature of nutrition, and he held some groundless opinions about quality in foods.

Nevertheless, the Hippocratic view that there was but “a single essential in all foodstuffs, with foods varying only in the amount of this single aliment” that they might contain, lasted until the 18th century. In the meantime, Aristotle summarized the Hippocratic view in the following words:

Either because of the quality of things taken or through their diversity or because the things taken happen to be strong and difficult of digestion, residues are thereby produced…And when the things t hat have been taken are of many kinds, they quarrel with one another in the belly, and … there is a change into residues … From the residues arise gase s, which having arisen, bring on disease.

For more than 2000 years, nutrition has been viewed as a dominant force in medicine. The Hippocratic view of a single aliment gave way to the forceful chemico-analytic era of Liebig, Mulder, Lavoisier and Magendie. Their endeavors culminated in the discovery of four chemically-defined categories of substances: proteins, carbohydrates, fats and minerals.

It was Antoine Laurent Lavoisier (1743-1794), with his experiments in guinea pigs and his laboratory assistant, who was able to demonstrate the similarity between animal and man and thus became known as the Father of Nutrition. He repudiated the earlier theory of phlogiston, propagated by Stahl (1660-1734). He brought together the findings of his predecessors to explain the phenomenon of respiration. Later in the same era, it was Magendie who first distinguished between the different kinds of foodstuffs. Although these advances were made possible by agricultural chemists, Western medicine quickly embraced the biologic era, with the univalent concept of etiology of diseases (i.e. one dietary deficiency, one disease) as with the univalent etiology of infectious diseases (i.e. one pathogenic microorganism, one disease). Thus, the idea that a disease could be caused by a lack of something as well as by the noxious and pathogenic presence of something was a revolutionary idea and was first clearly demonstrated for human beriberi in 1897. The demonstration of human beriberi was followed by Funk’s broader generalization of 1912 that not only beriberi, but also scurvy, pellagra and rickets were caused by a lack in the diet of “special substances which are of the nature of organic bases, which we call vitamines.” Other scientists of this era include F.G. Hopkins (1861-1947), J.Drummond (1891-1952) and McCollum, 1879-1967) among others. It is to be noted that the most basic nutrition research had been concluded since 1900. However, the first protein structure was not fully described until 1945. In spite of the current wide knowledge of nutrition, there are still many myths about food in the Nigerian culture. For example, is there any health advantage of consuming honey instead of refined sugar? Your class will be requested to supply as many myths as you can bring to class. Nutrition has come of age, having being recognized as an independent field of study since 1926. Kruse later remarked that

“there is no branch of medicine that does not have some aspect of nutrition within its domain.”

The history of man is intractably linked to his food, his feeding habits and the role that these play in his health. This relationship is modified by food availability and his state of health. When food is in short supply his health suffers and when food is abundant, his health is robust.

Human Nutrition touches on virtually every aspect of human endeavor, as it is of central importance to health. When one is well-nourished, it reflects in one’s appearance. The individual has vitality (he does not tire easily). He is emotionally stable and enthusiastic about life. On the other hand, when one is undernourished, he is inclined to tire easily (he lacks stamina). He is irritable and gets easily anxious. In general, such people are much more susceptible to illnesses. Furthermore, there are long-term effects of poor feeding habits on the lifespan and productivity of a people and a nation. Within a nation, the long term effects of poor nutrition may reflect in the overall height, weight, productivity and longevity of the nationals. Thus, the kind and amount of food consumed by a person have a great influence on his well-being, since his appearance is a reflection of what he eats.