Publisher Summary
Nutrition is the result of dietary practices after foods have been eaten, digested, and nutrients absorbed into the blood. It is the science of nourishing the body—the food that is eaten and the way that the body uses it. The nutrients in food are those chemical components of the food that perform one of three roles in the body: (1) to supply energy, (2) to regulate body processes, or (3) to promote the growth and repair of body tissue. People throughout life have need for the same nutrients but in different amounts. Therefore, the body is the product of nutrition. Heredity provides the blueprint for the body, and nutrition supplies the building materials. The science of nutrition is a relative youngster in the scientific field. However, at present, nutrition occupies an important place in a number of college and university curricula, including home economics, animal science, horticulture, medicine, and the allied health or paramedical fields. With the rapid advances in research, knowledge of nutrition is constantly expanded, and new interpretations and applications are presented. The primary source of this expansion in knowledge of nutrition is in the pure sciences of chemistry and physics applied to biological structures and processes. This chapter provides an overview of the study of nutrition. It highlights the basic preparations that need to be made for the study of human nutrition.
OVERVIEW OF THE STUDY OF HUMAN NUTRITION
From early childhood, people are taught that the basic physical needs of man are food, shelter, and clothing. Since the beginning of recorded history, man has struggled desperately to acquire enough to eat. History records a select few who indulged heavily in consumption of excessive food (e.g., King Henry VIII), but the mass of humanity has been highly concerned with “filling its stomach,” not questioning whether the food had a purpose or a function as long as it relieved hunger. Only since 1890 to 1910 has the function of food been given serious consideration by men in research and medicine. Since 1910 they have been trying to describe a “recommended diet” for a long healthy life. Much confusion has reigned in the struggle to define an adequate diet, as is illustrated by Ronald Deutsch in his book entitled Nuts Among the Berries, by Frederick J. Simoons in Eat Not This Flesh, and by Gerald Carson in the illustrated history of “patent medicines” entitled One for a Man and Two for a Horse and in his Cornflake Crusade. Other authors have conveyed the complexity of man’s concern for food in such books as The American and His Food by Richard O. Cummings, The Geography of Hunger by Josue’ De Castro, Attack on Starvation by Norman W. Desrosier, and The Ecology of Malnutrition by Jacques M. May. Prominent among all these treatises is A History of Nutrition by E. V. McCollum which further reflects the fact that man had great difficulty in clearly defining an “adequate diet.” Man long has been confused about what to eat. However, only recently through economic prosperity and abundant agricultural production of food in the United States have the majority of people had a choice in what to eat. As a result food fads, quackery, and unwise food selections have increasingly become a major concern of those who are abreast of research and are genuinely concerned about human health.
Few discoveries in medicine have been met with wider acclaim than the revelation that certain components in foods markedly improve man’s ability to live longer and to perform more effectively. Most people believe their state of health from day to day depends on what they eat. Few people realize the profound effect of the afferent stimuli to the brain from the sensory reaction to sight, smell, touch, and taste of the food. Conditioning and learning are also important to the acceptance of foods. Diets vary with cultures, races, nations, and even with regions and the seasons of the year, but nutrition is universal.
Nutrition is the result of dietary practices after foods have been eaten, digested, and nutrients are absorbed into the blood. Nutrition is the science of nourishing the body – the food that is eaten and the way that the body uses it! Graham Lusk in 1906 at Physiological Laboratory, Cornell University Medical College and the Russell Sage Institute of Pathology in his classic treatise, The Science of Nutrition gave this definition: “Nutrition may be defined as the sum of the processes concerned with growth, maintenance and repair of the living body as a whole or of its constituent organs.” These processes include the chain of events whereby the nutrients obtained from food reach the individual cells where they are used for energy, built into the cellular structure, or become constituents of compounds performing a regulatory function. Thus the nutrients in food are those chemical components of the food that perform one of three roles in the body: to supply energy, to regulate body processes, or to promote the growth and repair of body tissue. All people throughout life have need for the same nutrients but in different amounts. Therefore, the body is the product of nutrition; heredity provides the blueprint for the body, and nutrition supplies the building materials.
LAYMAN’S VIEW OF PHYSIOLOGICAL FUNCTIONS OF FOOD
GO POWER: | To supply energy, furnished by carbohydrates, fats and proteins, and regulated by vitamins and mineral elements. |
GROW POWER: | To build and maintain cells, tissues and organs, furnished by water, protein, vitamins, minerals, and energy. |
GLOW POWER: | To regulate body processes for energy and maintenance, furnished by all nutrients coordinated and functioning together. |
In its broadest sense, the subject of nutrition is concerned with those physiological functions of the body related to the nutritive constituents of foods and to a chain of events whereby these constituents become available for utilization by the cells. Elimination of wastes and the regulatory mechanisms of the body must be considered as a part of the nutritional processes.
In discussions on the nutritive needs of the body, the terms diet, food, foodstuff, and nutrient have been used. These terms are sometimes used synonymously; foodstuff was the original term to refer to the constituent substances of food and had essentially the same meaning as nutrient in current usage. Natural foods usually contain more than one nutrient; for example, analysis shows that milk is composed of water, protein, fat, carbohydrate, mineral salts, and vitamins. On the other hand, food extracted from natural agricultural products may be pure, as for example, oil from cottonseed or corn, starch from corn, sugar from beets or from the sap of sugar cane, and many others.
Nutrition now occupies an important place in a number of college and university curricula, including home economics, animal science, horticulture, medicine, and the allied health or paramedical fields. With the rapid advances in research, knowledge of nutrition is constantly expanded and new interpretations and applications are presented. The primary source of this expansion in knowledge of nutrition is in the pure sciences of chemistry and physics applied to biological structures and processes. An example of this type of research is that which resulted in the identification of the deoxyribonucleic acid (DNA) molecule identified as a key structure in he...