Since ancient times, people have understood the great importance of healthy food. The thinkers of antiquity, Hippocrates,
Celsus, Galen and others devoted entire treatises medicinal properties of various types of food and reasonable consumption. An outstanding scholar of the East Abu Ali Ibn Sina (Avicenna) considered food a source of health, strength and vitality.
Mechnikov believed that people grow old and die prematurely due to malnutrition, and that man is rational eating, can live 120-150 years.
Nutrition provides a vital function of the human body, supplying him with the energy necessary to cover the costs of the processes of life. Update cells and tissues also occurs due to intake of food "plastic" of substances - proteins, fats, carbohydrates, vitamins and mineral salts. Finally the food - the source of the formation of enzymes, hormones and other regulators of metabolism in the body.
In order to maintain the normal flow of energy, plastic and catalytic processes the body needs a certain amount of different nutrients. The nature of power depends on the body's metabolism, structure and function of cells, tissues, organs.
Proper nutrition, subject to the conditions of life, work and life, provides a constant internal environment of the human body, the activities of various organs and systems, and thus, is a prerequisite for good health, harmonious development, high performance.
Improper diet significantly reduces the body's defenses and operation violates the metabolic processes that lead to premature aging and may contribute to the emergence of many diseases, including infectious origin, as the weakened organism is exposed to any negative impact. For example, excess food, especially when combined with mental stress, lack of exercise, alcohol consumption and smoking, can lead to many diseases.
World Health Organization (WHO) to the number of diseases associated with excess power, attributed atherosclerosis, obesity, gallstones, gout, diabetes and polyosteoarthrosis. Overeating is often the cause of diseases of the circulatory system.
As a result of malnutrition and hunger appear diseases of malnutrition, especially widespread among the population of developing countries and dependent.
According to WHO, at present the necessary amount of food provided by at least one third of the world population.
Constant malnutrition generates kwashiorkor - a serious disease of children as a result of protein deficiency of food, which is widespread in the countries that were until recently in colonial dependence. In this disease, slowing growth and mental development in children, impaired bone formation, changes occur in the liver, pancreas.
The problem solved by the power of the population in terms of food necessary energy value (calorific value). Realization of the Food Program provides a significant improvement of the Soviet people the power structure by increasing the production of meat, dairy products, fruits and vegetables.
It is planned to expand the range of food products, to improve their quality.
The growth of material well-being allows you to organize on the basis of scientific rational nutrition of the entire population of our country.
The rational is considered a food, which ensures the normal functioning of the organism, a high level of efficiency and resistance to adverse environmental factors, the maximum duration of the active life.
The biological value of food is determined by the content in it of essential nutrients necessary for the body - in proteins, fats, carbohydrates, vitamins, mineral salts. For a normal life of a person it is required not only to supply it with adequate amounts of energy and nutrients, but also to observe certain relationships between numerous nutritional factors, each of which has a specific role in metabolism. Nutrition, characterized by the optimal ratio of nutrients, is called balanced.
The sources of nutrients are foods of animal and plant origin, which is conventionally divided into several main groups. The first group includes milk and milk products (cheese, cheese, kefir, yogurt, acidophilus milk, cream, etc.); second - meat, poultry, fish, eggs and products made from them; third - bread, pasta and bakery products, cereals, sugar, potatoes; fourth - fats; fifth - vegetables, fruits, berries, herbs; sixth - spices, tea, coffee and cocoa.
In nature there are no ideal food, which would contain a set of all the nutrients necessary for a person (with the exception of mother's milk). With a diverse diet, that is, a mixed diet consisting of animal and vegetable products, in the human body usually receives enough nutrients Islandsubstances. A variety of foods in the diet has a positive effect on its nutritional value, as different products complement each other missing components. In addition, a varied diet promotes better digestion.
Food as a source of energy
Over the life of a man performs a variety of physical movements associated with body movement and execution of work. All life in the body of work the heart, muscles, digestive and other systems, there is a decay of some substances and the synthesis of other, that is the basis of metabolism and constant cell renewal. These processes require energy, which the body receives by nutrients.
Food substances in the human body undergo changes as a result of oxygenation of air through the respiratory organs and spread to all cells. At the same time, a certain amount of energy is released in the form of heat. It should be noted that in the first phase of metabolism, food substances are transformed under the influence of enzymes into simpler ones: proteins into amino acids, complex carbohydrates into simple, fats into glycerol and fatty acids. In this phase, as a result of the breakdown of nutrients, energy is not only not released, but is consumed, as evidenced by the so-called specific dynamic effect of food. In the second phase, the decomposition products of food substances undergo further decomposition and are oxidized to carbon dioxide and water with the release of energy.
When full decomposition in the body 1 g protein and 1 g carbohydrates released by 4 kcal (16,747 kJ), 1 g fat - 9 kcal (37,681 kJ) ethanol - 7 kcal (29,309 kJ), organic acids (citric, malic, acetic, and others.) - on 2,5-
kcal (10,4670-15,0724 kJ). Other nutrients are not sources of energy. Thus, if you know exactly how much of the energy comes from food substances into the body (this is determined from special tables) can easily calculate the amount of energy received daily.
Food is not equivalent in energy value; It depends on their chemical composition. The main energy material is carbohydrates, fats and, in part, proteins. It does not follow from this that food substances can be replaced by each other and for the body it does not matter which products produce energy. The importance of various food products is determined not only by energy value, but also by their quality composition. So, simple carbohydrates (sugar and other sweets) do not contain any biologically valuable substances, except for energy, so the energy of these products is called "empty calories". When oxidizing the same in the human body ethyl alcohol coming from the alcoholic beverages produced toxic substances, harmful effect on health.
Depending on the amount of energy of all food products are divided into high, medium and low calorific value. For products with a high energy value are creamy and vegetable oils, animal fats, fatty pork, sugar, honey and confectionery. The average caloric value have a moderate-fat sausages, meat and fish, cream, cheese, bread and pasta, cereals. Low energy value characterized by vegetables and fruits, berries, milk, yogurt, lean meats, fish, lean cheese, eggs.
Received in excess in the body food substances are converted into fats and deposited in adipose tissue, which under certain conditions can lead to the development of obesity. Therefore, it is necessary to build a food ration so that the amount of incoming nutrients corresponds to the energy expenditure of the body for basic metabolism, physical activity, reception, digestion and assimilation of food. The main metabolism is carried out in the process of vital activity of the organism in a state of complete rest. In diseases accompanied by an increase in body temperature, it increases (with thyrotoxicosis, tuberculosis, pulmonary and cardiac failure).
Specific dynamic action of food due to its digestion and assimilation. Thus, the reception protein foods contributes to raising the basic metabolism by an average of 30%, fat - on 4-14%, carbohydrate - at 4-7%. The average basal metabolic rate increases under the influence of food on 10-15%, which is about 850 kJ per day. This property of an organism to expend a lot of energy on the specific dynamic action of protein foods used to treat obesity.
Correspondence of incoming energy substances to the energy expenditure on its vital activity is provided by balanced nutrition. A reliable indicator of the correspondence between the intake and expenditure of energy in the body of an adult is the constancy of body weight. The excessive energy value of the diet leads to an increase in body weight. With a lack of food, the body spends the spare energy substances, as a result of which a person loses in body weight. With a long lack of nutrients, not only reserve substances are used, but also cell proteins, which significantly reduces the protective properties of the body and adversely affects the health status.
The need for human energy
In 1982, the Health Ministry new norms physiological needs have been approved in the energy and nutrients for the various population groups, developed by the Institute of Medical Sciences of the power. In determining the energy needs of adults were taken into account age, gender and the nature of work. According to these regulations, the adult working-age population aged 18- 60 years 5 divided into groups depending on energy expenditure.
The first group includes persons of predominantly intellectual work - heads of enterprises and organizations; Engineering and technical staff, whose work does not require significant physical activity; Medical workers, except for surgeons, nurses and nurses; Teachers, educators, except for sports; Literary workers and journalists; Employees of cultural and educational institutions, planning and accounting; Secretaries, clerks; Persons whose work is associated with a great nervous and insignificant physical strain (workers of control panels, dispatchers, etc.).
The second group includes workers employed light physical work - engineering and technical personnel, whose work requires some physical effort; persons employed in automated processes; electronic industry workers; sewers; agronomists; livestock, veterinary professionals; nurses and nurses; department store merchants, service workers; Workers watch industry; communications and telegraph workers; teachers, physical education and sports instructors, coaches.
The third group includes people who perform moderate physical work: machine operators (engaged in metalworking and woodworking), mechanics, setters, adjusters; Physicians-surgeons; Chemists; Textile workers, shoe makers; Drivers of various modes of transport; Food industry workers; Workers of public services and public catering; Sellers of food products; Brigade leaders of tractor and field teams; Railwaymen; Water managers; Employees of auto- and electric transport; Machinists of hoisting and transport mechanisms; Polygraphists.
The fourth group unites people of heavy physical labor - construction workers; the vast majority of agricultural workers and machine operators; miners employed 'on the surface works; workers in the oil and gas industry; metallurgists and foundry workers, except for those classified as the fifth group; working paper and wood processing industry (slingers, riggers, de revoobrabotchikov, carpenters, etc.), the building materials industry workers, except for those classified as the fifth group.
The fifth group includes workers who perform particularly hard physical labor - miners employed underground operations; steelworkers; loggers and forest workers in the cutting of wood; masons; reinforced concrete; excavators; loaders that work is not mechanized; workers employed in the production of building materials, where labor is not mechanized.
The energy demand of the adult working population of our country is picked for three age groups: 18-29, 30-39 and 40-59 years. Due to lower body weight and less intense metabolic process in women need female body in an average energy 15% lower than men's.
In determining the needs of the adult working population aged 18-60 years in power for the average ideal body weight was adopted 70 kg weight for men and 60 kg - for women. Recommended averages of daily energy needs of the adult working population of our country, depending on the intensity of labor groups are presented in Table. 1.
T a b l e 1. The daily demand for energy (kJ) of the adult working age population (in brackets presents data in kcal)
|Group work intensity||Age,||Men||Women|
|1-I group||18—29||11 723 (2800)||10 048 (2400)|
|30—39||11 304 (2700)||9630 (2300)|
|40—59||10 676 (2550)||9211 (2200)|
|2-I group||18—29||12 560 (3000)||1.0 676 (2550)|
|30—39||12 142 (2900)||10 258 (2450)|
|40—59||11 514 (2750)||9839 (2350)|
|3-I group||18—29||13 398 (3200)||11 304 (2700)|
|30—39||12 979 (3100)||10 886 (2600)|
|40—59||12 351 (2950)||10 467 (2500)|
|4-I group||18—29||15 491 (3700)||13 188 (3150)|
|30—39||15 072 (3600)||12 770 (3050)|
|40—59||14 444 (3450)||12 142 (2900)|
|5-I group||18—29||18 003 (4300)|
|30—39||17 166 (4100)||-|
|40—59||16 329 (3900)||-|
Notes. 1. Women are forbidden to engage in the Soviet Union especially in heavy physical labor. 2. 1 4,1868 kcal equal (rounded 4,187) kJ.
Energy demand of men aged 60-74 years retired, on average, no more than 9630 kJ (2300 kcal) per day, at the age of 75 years and older - 8374 kJ (kcal 2000). The need for women's power - 8792 (2100 kcal) and 7955 (1900 kcal), respectively.
Energy demand of persons living in the Far North, on average, 10-15% higher, and living in the southern parts of the country - to 5% below what those who live in the temperate zone.
Plastic function of nutrients
Nutrients (proteins, fats, carbohydrates, vitamins, minerals) are an important source of material for the construction of cells and tissues, enzymes, hormones, and other vital substances; they are used as biocatalysts. In humans, there are processes continuously update the various elements of cells and tissues. Some cells die, and instead of them there are others. All this requires a constant influx of nutrients into the body.
The main plastic material for living organisms are proteins. Exchange of proteins as a central link in the biochemical processes is the basis of life. Proteins make up about 15-20% wet weight of various human tissues and lipids (fats) and carbohydrates - whole 1-5%. Of the proteins and lipids are built biological membranes, plays an important role in cell function. Muscle tissue, heart, liver, bone marrow and even contain significant amounts of protein.
The only source of protein and essential amino acids for humans is food: almost all products, with the exception of sugar and vegetable oils, contains various proteins. Due to the moderate heating and cooking, the nutritional value of protein products is increasing, they are better absorbed.
Proteins are the basis of most enzymes. The building complex of enzymes are involved, and other substances, such as vitamins. Enzymes perform the basic functions of the metabolism, the construction of specific human cell structures. Using enzymes are synthesized in the body energy substances which are destroyed with the desired energy allocation body.
An important function of proteins is to provide barrier properties, the tissue specificity of the organism, its immunity.
The complex compounds with lipids, carbohydrates, vitamins, minerals, metals, pigments, medicines and even oxygen proteins function as transport of these substances to various organs and tissues. They promote maintaining a certain amount of water in the cells and intercellular space.
Fats and fat-like substances (lipids) are the building blocks of living cells and provide the physiological functions of the body.
The fat layer around the internal organs of the abdominal cavity protects them from mechanical damage. In the subcutaneous tissue fat as a bad conductor of heat limits the heat and protect the body from hypothermia.
Minerals are involved in the metabolism of cells of various tissues. Of particular importance are minerals in the building of bone density and abutmentwhich ity to physical activity depends on calcium and phosphorus. Without minerals in the body could not be carried out many enzymatic processes. Minerals affect the blood, maintain the osmotic pressure in the cells and extracellular fluids are involved in the transport of oxygen to tissues, are part of many hormones and other biologically active compounds.
Water and its dissociation products are constituent parts of a living cell. Only in an aqueous medium can many biochemical reactions take place. In the body of an adult with a body weight of 65 kg contains about 40 l of water, of which 25 l is inside cells and 15 l is in extracellular fluid. The exchange of labor in the body is very intense. About 2,5 L of water is excreted daily in urine, feces and exhaled air. By sweating, the body temperature is constant. With increased ambient temperature or intense physical work, sweating is dramatically increased. In some cases, the amount of sweat emitted by a person per day can reach 10 l. That's why regular water intake is an important factor in maintaining the constancy of the body's internal environment, as well as the structure and functions of all cells and tissues.
Thus, all nutrients arriving at the body, play a role in the plastic structure of tissues, cells, intracellular structures, and biologically active substances that perform various physiological functions.