Under nutrition understand nutrition, sufficient in quantity and in full quality. The basis of a balanced diet is balanced (optimal ratio) of all components of food. In that balance is required not less than 60 substances that make up the food of man (essential and non-essential amino acids, polyunsaturated fatty acids, phosphatides, lecithin and sterols, including cholesterol, beta-sitosterol, fats, sugar, starch and pectins, vitamins, mineral elements, organic acids and other). Modern food hygiene studies not only the usefulness of exogenous entering the body of essential nutrients, but also the issues of optimal synthesis of these substances in the organism.
Rational nutrition is an important factor in improving public health. Good food should take into account the age, nature of work, floor, climatic, national, and individual characteristics. The monotony of the food hampers the balance of power, inhibits internal synthesis of substances. Off for a long term individual food groups and sharp narrowing their range limit the ability of the body in the selection of essential substances, their balance and maintain a normal level of internal synthesis. The problem the best use of synergistic properties of food substances, allowing to provide balanced and full nutrition during its minimum energy value, is an important task of food hygiene. Developed daily calorie needs for people of active age in settlements with good or satisfactory public services (table. 1)and the rules of the daily requirement of protein and fats (table. 2). Installed and tested in practice the following principles of balance of supply : 1) the ratio of proteins, fats and carbohydrates - 1:1:4; 2) the amount of proteins (see Proteins in the diet) is 14-15% of daily calories, 3) number of animal protein - not less than half of the daily requirement of protein; 4) the amount of fat (see Fats in the diet) - 30% of daily calories, 5) the share of animal fat - 75-80% and vegetable oil - 20-25% of daily rate; 6) the amount of carbohydrate - 55-56% of the daily calorie intake.

Note. Professional groups: I - professions that are not related to physical work; II - the profession of a mechanized labour; III - the profession is not mechanized or partially mechanized labour; IV - the profession of heavy, non-mechanized work.

* The need for nutrients and anergy is given without taking into account the nutritional value of milk.

Children need a relatively larger number of plastic substances. With this requirement in mind for children developed special physiological norm of nutrition (table. 3).
Differentiation of the energy value of nutrition, depending on climatic conditions is made by reducing the consumption of fat in the southern zone and promote it to the North. The proportion of protein in all climatic zones remains constant. Changes significantly regulation of carbohydrates, whose share increased in the diet of people living in the southern zone, and a little diminished in the North.
Energy indicators power varies in different climatic zones. In the Northern zone they raised and South lowered. Caloric value and proportion of main nutrients in different climatic zones for the male population engaged in intellectual work and other activities not connected with physical labor, listed in table. 4.

Nutrition of older persons is built taking into account features of an aging organism: reduction of intensity of oxidative processes, the fall of the cell activity, slow the course of metabolic processes, reducing the functionality of digestive glands and others, reduction of the functions of all body systems and the development of atrophic processes. Hence the need to limit the power in old age. This restriction is in accordance with the amount of physical activity and the General level of mobility of elderly people. For people of elderly and senile age developed the following physiological norm of nutrition (table. 5).

For people over 70 years norms needs for energy and nutrients see table. 6.

In the diet of older people less carbohydrates fats and partially (daily value not more than 80 g, including 70% of animals and 30% of plant). Especially limited refined products: sugar, confectionery and bakery products of the highest quality, polished rice, semolina and others On the share of sugar should have no more than 15%, and the share of carbohydrates potatoes, vegetables and fruit at least 25% of the total number of carbohydrates daily diet. It is desirable to increase the specific weight of whole grain products (bread of wholemeal flour and others). Rational norm of proteins in old age is considered 1 8 1 kg of body weight. In old age is important qualitative aspect of protein daily diet.
Especially valuable are the milk proteins are the most profitable sources of essential amino acids (see). Due to the products of animal origin must be provided about 60% of the total protein diet, with half of this amount should be milk proteins.
The power supply must take into account digestibility of food. The coefficients digestibility of basic foods are given in table. 7.

In a balanced diet is regarded as crucial vitamin-balanced. Vitamins (see) are vital in all age groups. Norms of requirements for vitamins (mg/day) are given in table. 8 and 9.

* Other vitamins norms need not specified yet and are under development.

* Other vitamins norms need not specified yet and are under development.

Not always (for example in the winter months) it is possible to satisfy the need of the body in all vitamins by natural of their content in food products. Hence the need vitamin supplements population synthetic vitamins. In the USSR enrichment with vitamins (C, B1, B2, PP and A) subject flour, sugar, milk, edible fats (table. 10).

Fortification can be carried out by direct injection of vitamins in food before its consumption (in institutions, hospitals, sanatoriums, factory and other public canteens). First fortification ascorbic acid subject children in children's institutions (35 mg/day. on child) and patients in hospitals (100 mg/day in patient). Important role in the diet are mineral substances (see).
Mineral substance reasonably attributed to biologically necessary substances. To ensure their assimilability of mineral substances should be balanced.
Physiological needs of some mineral elements are given in table. 11.

Important mode of supply. For an adult, the most justified fourfold meal intervals between meals in 4-5 hours (table. 12).

Note. Option I - 3 meals; option II - 4 meals a day.

For people doing mental work and old age diet may be more even without sharp selection of Breakfast and lunch.