All life processes in the body are in a strong dependence of diet, and what constitutes for its food – since the very first days of the life. Every living organism in its live processes continuously spends some constituent substances. Much of these substances are being “burned” (oxidized) in the body, resulting in energy release. This energy the organism uses to maintain a constant body temperature, also to ensure the normal functioning of the internal organs (heart, respiratory system, circulatory system, nervous system, etc.) and particularly to perform any physical work.
Theory of Nutrition
Food is the essence and the first condition of life. Not surprisingly, all the universal natural science concepts have been including the theory of nutrition as their important and essential part. In the history of science there were two theories of nutrition. The first occurred in ancient times, and the second – the classical theory of a balanced diet – has been finally formed at the end of XIX – the first half of XX century.
The ancient theory of nutrition is associated with the names of Aristotle and Galen, and is a part of their representations of the living. According to this theory the power to all structures of the body is due to the blood, which is continuously formed in the digestive system of nutrients as a result of a complex process of unknown to nature, in a way similar to the fermentation. The liver cleanses the blood, and then it is used to supply all the organs and tissues. Based on these representations, numerous therapeutic diets were built, that were to provide an easier transformation of food into the blood with the best qualities of the latter.
The classical theory of a balanced diet is closely related to common belief about the ideal food and optimal balanced diet. This theory is based on a balanced approach for the assessment of diet, and it still retains its value up to now. In its simplest form, this approach focuses on the part that the body should have a supply, composed of such molecular structure, that would compensate for their expense and loss from the metabolism, work, and for growth that also applies to the young organisms.
The classical theory is also based on the following fundamental principles:
- inflow of substances must exactly match their expenses;
- influx of nutrients provided by the destruction of structures and absorption of food nutrients – nutrients needed for metabolism and construction of structures of the body;
- utilization of food is carried out by the body;
- food consists of several components of different physiological significance: food, ballast and toxic substances;
Metabolism is determined by the level of amino acids, sugars, fatty acids, vitamins and some salts, so thus we can build a so-called elemental (monomeric) diets.
Nutrients are called such chemicals or individual elements, that are essential for the body and its vital processes. The common property of proteins, fats and carbohydrates is their ability to satisfy the energy needs. However, they have relatively high levels of energy released when exposed to the digestive enzymes.
The Food composition
The food should contain proteins, fats, carbohydrates, vitamins, minerals and water. The need for particular amount of food, as well as the particular nutrients may depend on the age for the children, and for the type of work and living conditions for the adults. To better meet this need of the body, it is necessary to know how much energy is being consumed on a daily basis. It is known for a fact, that the energy produced by the body eventually being released as heat.
Under the best nutritional standards we understand such rules, that completely cover the needs of the bodies for adults, and in addition, the needs of growth and development for the children. Proper diet promotes working capacity, and is one of the most important conditions for the appropriate functioning of the gastrointestinal tract.