Physiological standards for children's nutrition

There is no doubt that nutrition as a form of providing building material and energy for the entire process of growth and development of a child is of great importance for the health of children and the final results of growth and development. At the same time, even at the present time it cannot be said that in the nutrition of a child, as in the nutrition of an adult, all scientific truths and practical solutions are available to us today. It must be stated that the extremely conservative human genome, preserved in our cells to this day, carries both food orientations and dependencies conditioned by the distant past, including information about the habitat to which it was adapted at the time of the emergence of man or his closest ancestors. It is possible that these were orientations to those food products that the world ocean was rich in and the land onto which our ancestors crawled out of the ocean.

Fortunately for pediatricians, the main food product of a breastfed baby - mother's milk - has changed relatively little and mainly in the part where its composition is determined by the diet of the nursing mother. Therefore, breast milk remains the unshakable "gold standard" of pediatric dietetics. As for human nutrition in the period after weaning from the mother's breast, we have to discover many completely new and unexpected things.

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Physiological nutrition

The term "physiological nutrition" means ensuring, with the help of a diet, the normal life activity of a child for a given age, his growth and development. The fundamental difference between physiological nutrition of children and physiological nutrition of adults is, first of all, its focus on ensuring growth and development. Dietetics, or nutritionology, of childhood is, first of all, "dietetics (nutritionology) of development". The concept of "physiological nutrition" also includes some narrower or more specialized concepts and definitions inherent to them.

One of the most complex and key theoretical aspects of developmental dietetics is the study of the mechanism of the emergence of persistent, often lifelong, influences of nutritional features. Naturally, the latter are more characteristic of the nutrition of the fetus during pregnancy, closely related to the nutrition of the pregnant woman herself. Such influences are very convincing for the nutrition of young children, but they also exist in all subsequent periods of childhood until the complete completion of growth and development of the body.

In early childhood, the issues of dietary support for fine differentiations of nervous tissue and the brain, development of bone tissue, blood vessels, skeletal muscles and myocardium, and the endocrine apparatus of reproduction are more acute than in subsequent age periods. Suboptimal provision of children of primary and even senior school age with iron, selenium, iodine, zinc, calcium, etc. may be a sufficient basis for non-optimality or more significant disturbances in the formation of intelligence, the musculoskeletal system or connective tissue as a whole, the reproductive sphere, a decrease in physical performance and the terms of future life due to diseases already in adulthood.

All of the above differs significantly from the dietetic concepts of the recent past. Previously existing concepts of children's nutrition were focused more on the analysis of the connections between nutrition and health within the immediate future. It is easier for a clinician, as well as a nutritionist, to navigate such immediate phenomena as hunger or satiety, tolerance or intolerance of foods, the presence of reactions to food intake, the characteristics of the dynamics of body weight and growth during the period of feeding with a given diet, etc. From the standpoint of developmental dietetics, these are also important characteristics, but the presence of even the most positive immediate assessments is not enough to recognize the diet as adequate for use or optimal.

When discussing the mechanisms of long-term effects of nutrition on development, the role of the following processes must be taken into account.

1. The direct influence of environmental factors, primarily nutrients, on the expression of genes and primarily genes that regulate development, and the resulting correction of the genetic program and intensification of growth and differentiation processes.
2. Frequently occurring "adaptations" to nutrient deficiency by replacing the deficient nutrient with available and similar in chemical properties or structure chemical (biological) substances or compounds. The result of such a substitution is the formation of tissue or cellular structures, in particular membranes and receptors with non-optimal functional characteristics. Examples include the replacement of deficient long-chain polyunsaturated ω3- and ω6-fatty acids with oleic acid, the formation of brain glucocerebrosides instead of galactocerebrosides in the absence of lactose (galactose) in the diet, the use of strontium, aluminum or other elements in osteogenesis in the absence of sufficient calcium intake, etc. Even the development of lead intoxication is largely due to a lack of iron in the diet and its pseudo-compensation - substitution with lead.
3. The introduction of elements of chaos and heterochrony into nutrient-dependent sequences of growth and differentiation processes with the resulting discordance of interstructural and intersystem connections and the final non-optimality of the formed structures and chains of their integration.
4. Induction under the influence of nutrients of metabolic and neuroendocrine chains of developmental regulation that do not correspond to a given period of ontogenesis, or "switching" of the biological clock of development. An example is the effect of early introduction of glucose into the diet of a newborn with subsequent activation of insulinogenesis, reduction of oxidation and use of fatty acids and other metabolic changes characteristic of later periods of childhood - the physiological basis and prerequisites for the formation of "syndrome X" or "cancrophilia syndrome" (according to V. M. Dilman).

Balanced nutrition

The term "balanced nutrition" characterizes not only the sufficiency of nutrients, but also the observance of certain relationships between numerous replaceable and irreplaceable nutritional factors. Thus, the concept of balance and imbalance refers primarily to the detailed biochemical characteristics of diets.

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Adequacy of nutrition

The term "adequacy of nutrition" as applied to physiological nutrition includes not only the idea of the sufficiency and balance of the diet, but also compliance with a wide range of additional conditions, often changing for children of different age groups. The choice of products, the recipe for their culinary processing, the final volume or consistency, taste, osmotic or immunoallergological characteristics may or may not correspond to the age or individual characteristics of the child, thereby representing a greater or lesser degree of inadequacy of nutrition even with its highest completeness in terms of content and balance of nutrients.

Within the framework of adequate nutrition, it is possible, but with great conventionality, to consider the problems of natural, mixed and artificial feeding of children of the first year of life. Only natural feeding can be considered strictly adequate for children of the first year of life. This is determined by the extremely complex integral effect of the nutritional and biological regulatory role of both the mother's native breast milk itself and the feeding process.

Considering the very significant influence of quantitative characteristics, in particular the energy value of the diet and its protein content, on the growth rate of a child, especially in the first months and years of life, within the boundaries of adequate nutrition, it is possible to distinguish its various levels.

It is reasonable to call maximum nutrition such adequate nutrition, in which the rate of physical development is above average (above 75 centiles according to speed standards); average - adequate nutrition at an average growth rate (from 25 to 75 centiles); minimum - at a low growth rate (from 3 to 25 centiles according to the growth of length or body weight). Close to the above concepts, one can put such as "forced nutrition", which occupies a middle position between physiological and therapeutic. Forced nutrition is physiological in essence, since it is designed to ensure vital functions, growth and development, but is used exclusively in the recovery period after diseases that have led to inhibition or cessation of growth and body weight dynamics. To ensure "catch-up" growth and recovery processes in such children, an increase in protein and energy load is used while maintaining a balanced diet relative to this already increased load.

The category of concepts intermediate in the range between physiological and therapeutic nutrition includes such a concept as "preventive" nutrition. Most often, this term denotes adequate nutrition, but with features that provide a specific effect in compensating for the constitutional or hereditary predisposition to a certain group of diseases or pathological conditions identified in a child. In recent years, the term "functional" nutrition has become widespread, used for long-term modifications of physiological nutrition with a very broad preventive focus. The range of substances in functional nutrition that allow achieving higher levels of health is constantly expanding.

The most common recommendations for healthy people's nutrition include 3-5 servings of vegetables (except potatoes), fruits or juices of different colors per day, which guarantees sufficient supply of functional nutrition substances.

One of the sections of functional nutrition is the study of biocurrents and prebiotics, which examines the aspect of synergism between the human body and saprophytic bacteria.

Phytochemicals
Carotenoids (β-carotene, lutein, lycopene, ziaxanthin)	Flavonoids (resveratrols, anthrocyanins, quercetins, hesperidins, tengeritins)	Sulforaphanes, indoles, elagic acid
Vegetables
Broccoli	Broccoli	Broccoli
Carrot	Garlic	Asparagus cabbage
Leafy cabbage	Lettuce	Brussels sprouts
Pumpkin		Cabbage
Red pepper		Cauliflower
Spinach		Leafy cabbage
Tomatoes		Turnip
Turnip		Leaf beet
Fruits and berries
Apricot	Cherry	Currant
Kiwi	Pears	Raspberry
Mango	Apples	Blackberry
Papaya	Blueberry	Blueberry
Pink grapefruit	Grapefruit	Grapefruit
Watermelon	Kiwi	Kiwi
	Liletta	Liletta
	Orange	Orange
	Pink grapefruit	Pink grapefruit
	Red grapes	Red grapes
	Strawberry	Strawberry
	Strawberries	Strawberries
	Tangerine	Tangerine
	Mandarin	Mandarin

Phytochemicals - nutrients with high antioxidant activity

Substances	Carriers
Capsaicins	Peppers
Flavonoids	Citrus fruits, tomatoes, carrots, apples, cherries, peppers, berries
Indoles	White cabbage and asparagus (broccoli)
Isothiocyanates	Broccoli, horseradish, mustard
Lycopene	Tomatoes, red grapefruits
Β-allylcysteine	Garlic, cucumbers
Triterpenoids	Licorice root, citrus

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Probiotics

The concept of biota is very closely related to health and nutrition issues. Biota is the totality of all living organisms that accompany human life in the spaces of the intestines, skin and mucous membranes.

What is our biota - the “third world of man”, occupying an intermediate position between his external and internal worlds?

Of the total number of cells in the human body, and there are 10 times more of them than there are stars in the Milky Way, 10% belong to the human body itself and 90% to its biota, i.e. the sum of bacteria, fungi, protozoa and life forms such as Arcaea. In the intestine alone, their number ranges from 10 to 100 trillion. At present, the biota of the gastrointestinal tract is represented primarily by the following groups of bacteria or bacterial cultures.

Probiotics - 1014 cells, more than 500 species.

Main bacterial cultures:

Lactic acid bacteria (56 species)	Bifidobacteria (32 species)
L. rhamnosis GG	B. bifidum
L. acidophilus	B. longum
L. casei	B. breve
L. bulgaricus	B. infantis
	B. animales

The main functions of biota:

• participation in the formation of the capillary network of the intestinal wall;
• stimulation of non-specific immunity;
• suppression of the FIAF protein, which limits fat formation in the body;
• participation in the metabolism of cholesterol and bile acids;
• synthesis of vitamins, especially vitamins B|, B6 and K;
• digestion of plant fiber;
• extraction of energy from food;
• formation of short-chain fatty acids to nourish the colon wall;
• together with human milk protein (HAMLET* factor) - stabilization of DNA structures.

*HAMLET is a multimeric α-lactalbumin from human milk that induces selective apoptosis of cells with potential for oncological transformation, primarily in the gastrointestinal tract and lymphoid tissue.

Finally, we can agree with the validity of the existence of such a concept and term as "optimal" nutrition. This is still a purely theoretical concept or abstraction, which, as applied to pediatric nutritionology, implies achieving such an ideal level of nutrition that it will not only be adequate or narrowly preventive, but will also provide the most positive impact on the entire subsequent period of life - it will become a factor in the formation of long-term health and active longevity. The definition of "optimal breastfeeding" is quite clearly outlined.

Therapeutic nutrition in pediatrics

Therapeutic nutrition in pediatrics, unlike the therapeutic nutrition of adults, must necessarily be oriented toward the simultaneous solution of two fundamental tasks - maintaining adequate physiological nutrition, sufficient to ensure the normal development of the child, and the actual therapeutic function, as applied to specific disease manifestations and metabolic disorders. Thus, it can be said that therapeutic nutrition in pediatrics is a special adaptation to the disease or to the conditions set by the disease, of all the laws and principles of developmental dietetics.

Where these conditions are met, we can talk about adequate therapeutic nutrition. In case of moderate violation of adequacy, we can talk about subadequate therapeutic nutrition. Finally, in the most dramatic clinical situations, therapeutic nutrition may become absolutely inadequate for some period of time. In these situations, there is a complete analogy between the use of inadequate nutrition and the use of highly toxic drugs, radiation or surgical methods of treatment that are traumatic but help save or prolong life. By analogy with these methods, such a characteristic as "aggressive nutrition" is often used for feeding a sick child. As a rule, this also includes such options for delivering therapeutic nutrition as enteral tube or parenteral nutrition. A certain logical paradox is the fact that the most serious reason for using aggressive nutrition is not so much the drama of the clinical situation and the need to protect the patient's life, but indications aimed at maintaining his adequate development, i.e. indications of a physiological nature.

"Sufficiency", "insufficiency" or "excess" of nutrition are clinical terms and do not refer to the diet, but to the nutritional status of the child. Qualitative nutritional deficiency is determined by identifying clinical or laboratory signs (symptoms) of deficiency of one or more vitamins, salts or microelements. Quantitative deficiency or excess is usually attributed to manifestations of impaired supply of protein or energy nutrients, which include fats and carbohydrates. The main manifestations of such predominantly quantitative deficiency are growth retardation, weight loss, partial or complete loss of subcutaneous fat, and decreased muscle mass in advanced cases. The widespread term "protein-energy nutritional deficiency" refers to the dominance of signs of quantitative nutritional deficiency.