Speaking about the composition of breast milk, first of all, one should distinguish between its qualitative and quantitative composition. If the qualitative composition is relatively constant and includes mainly water, proteins, fats, carbohydrates, vitamins, macro- and microelements, then the quantitative composition is subject to change. Changes in the quantitative composition of the main components of milk depending on the stage are presented in the table.

Quantitative composition of a woman’s breast milk in g/l

Changes in the composition of milk do not occur abruptly, but gradually, affecting not only the main nutrients(proteins, fats, carbohydrates), but also all biologically active substances (vitamins, hormones, minerals, etc.). Let us consider these processes in more detail, tracing changes in composition from colostrum to involutive milk.

Colostrum

It would be more correct to call colostrum not one of the types of milk, but its predecessor. It is secreted from the mother during the third trimester of pregnancy and the first three days after birth in the amount of 5-10 ml per day. This is a thick yellowish sticky liquid that is released not in streams, but in separate drops and is closer in composition to blood than to milk. Colostrum has a significant calorie content, thanks to which the child’s body, even with a very small stomach capacity, receives a sufficient amount of energy.

Components of colostrum that differ increased content

Components of colostrum characterized by reduced content

Transition milk

Three days after birth, blood begins to actively circulate in the mammary glands under the influence of hormones, increasing the production of early transitional milk. It is very similar to colostrum, but differs in larger volume and a changed quantitative composition of components. The content of protein, sodium salts, potassium, vitamins A, E decreases and the content of fat, carbohydrates, and B vitamins increases. After 7-8 days, the composition of milk continues to change, but at a lower rate than before, its stabilization begins to occur. This type of transitional milk is called late transitional milk. As for the volume of milk during this period, it begins to adapt to the amount that the child sucks, that is, to replace hormonal regulation volume comes the so-called autocrine.

Mature milk

2-3 weeks after birth, mature milk begins to be produced, which is characterized by the most stable composition. The concept of stability here is very arbitrary, since very slowly the protein content continues to decrease and the carbohydrate content continues to increase. Changes in the content of the remaining components are not of such a constant nature and are determined by the child’s needs for them, his age and other factors.

Involutive milk

Produced in the mammary gland during lactation. This stage occurs when the child is 2.5-4.2 years old, when the child is put to the breast only 1-2 times a day. The composition of milk at this time becomes more and more similar to colostrum. It contains especially a lot of macrophages, leukocytes, immunoglobulins, phagocytes and other anti-infective factors.

What influences changes in the composition of breast milk

Characteristics and properties of breast milk components

Today, about 500 components of breast milk are known, and the properties and role of each of them are not yet fully understood. All of them can be divided into several groups, differing in structure, properties and functions performed in the body.

Squirrels

Whey proteins and casein. Most of the protein in breast milk is represented by whey proteins, a smaller part is made up of casein fractions. The ratio of whey proteins to casein depends on the stage. In mature milk it is 60:40. The term “casein” is not entirely accurate in this case, since this protein is formed under the influence gastric juice from caseinogen, which, in fact, is found in breast milk. Breast milk proteins can be quickly absorbed by the baby's body. This is achieved through:

• small size of casein molecules (compared to casein cow's milk);
• the presence of proteolytic enzymes;
• the identity of 18 breast milk proteins to blood serum proteins, due to which they can be easily absorbed in the intestine and enter the blood unchanged.

The vast majority of protein supplied from food is a source of amino acids. In the absence or deficiency of certain amino acids (essential), the body will not be able to synthesize its own protein. Essential amino acids in newborns include phenylalanine, lysine, isoleucine, valine, leucine, methionine, threonine, tryptophan, histidine.

Free amino acids. In addition to protein, milk contains free amino acids. It is believed that the presence of free amino acids in milk, for example, taurine, is explained by the high need for them in a newborn baby, which are not covered only by protein.

Important! Free amino acids in milk complement protein, which serves as a building material for the body.

Breast milk contains a special fraction of proteins that is practically not destroyed in the baby’s digestive system and has immune activity, being components of the body’s defense system.

1. Lactoferrin– iron-containing glycoprotein. Due to its ability to bind iron, it can block this element in the composition bacterial cells pathogenic microorganisms thereby suppressing their growth.
2. Immunoglobulins is a group of whey proteins. Their variety is immunoglobulin IgA, which is capable of enveloping the mucous membrane of the intestines and throat, thereby preventing the penetration of viruses and bacteria through it.
3. Lysozyme– like lactoferrin, it has bactericidal activity, disrupting the integrity of the bacterial membrane. In human milk its concentration is 300 times higher than in cow's milk.
4. Alpha-lactalbumin— promotes the formation of peptides with immunoregulatory and antibacterial properties, supports the growth of bifid flora in the child’s intestines. When it is broken down in the gastrointestinal tract, bioactive lipids are formed, the so-called HAMLET complex, which helps destroy cancer cells.

Important! Proteins are a source building material for the body, have immune activity, regulate the course of biochemical reactions.

Enzymes and hormones. The main function of enzymes is to accelerate biochemical reactions, and hormones to regulate their speed. Enzymes in breast milk facilitate the absorption of its components, since the synthesis of the child’s own enzymes by the body is still insufficient. Thus, the enzymes pepsinogen and trypsin are directly involved in the breakdown of protein, lipase facilitates the breakdown of fat due to its partial hydrolysis before entering the stomach.

Nucleotides. When they talk about the protein content of milk, they often mean total protein, determined by the calculation method based on nitrogen content. However, the nitrogen-containing compounds of milk include not only proteins, peptides and amino acids, but also other nitrogen-containing compounds. These substances include nucleotides - nitrogen-containing compounds, precursors of DNA and RNA, the content of which in breast milk is 7-10 mg/100 ml. In the human body, their synthesis is limited and occurs only in certain tissues, so food is almost the only opportunity for entry into the body. Their functions are as follows:

• maturation of the immune system and formation of an immune response;
• a universal source of energy that promotes cell growth and division;
• participate in the formation normal microflora intestines and metabolism of essential fatty acids.

Fats

Human milk fat, like most natural fats, has several main components:

• triglycerides;
• phospholipids;
• sterols.

Triglycerides. They are the main part of fat and are esters of glycerol and fatty acids. The structure of triglycerides in human milk differs from triglycerides of other fats in the position of palmitic acid, which ensures its complete absorption by the child’s body, and in the predominance of polyunsaturated fatty acids over saturated fatty acids. Polyunsaturated fatty acids are not synthesized by the human body and are essential. A special place among them is occupied by linoleic acid (a precursor of arachidonic acid) and α -linoleic acid(precursor of docosahexaenoic and eicosapentaenoic acid), which perform a number of important functions:

• contribute normal growth;
• participate in the formation of the immune response;
• necessary for the normal formation of the brain and neuroretina;
• are involved in mechanisms that activate digestion and promote the maturation of intestinal cells.

Sterols. Their most important representative in breast milk is cholesterol, which is involved in the formation cell membranes, nerve tissue, the synthesis of certain vitamins, in particular vitamin D, hormones and other biologically important substances.

Phospholipids. Their most important representative is lecithin, which limits the deposition of ballast fat and promotes protein synthesis in the body.

Carbohydrates

Human milk carbohydrates contain lactose and oligosaccharides. Fructose, sucrose (less commonly maltose) are not always found.

Lactose. It is the main carbohydrate in human milk. This carbohydrate is found only in milk and is therefore also called milk sugar. Along with providing the body with energy, it performs a number of other important functions. So, when lactose breaks down in the small intestine, galactose is formed, which:

• participates in the development of the central nervous system;
• contributes to the formation beneficial microflora intestines.

For the breakdown and further absorption of lactose, it is important that digestive system the child has synthesized a sufficient amount of lactase, the enzyme that breaks it down, otherwise significant amounts of undigested lactose lead to the manifestation of symptoms. Small amounts of undigested lactose are considered normal occurrence and, entering the large intestine, it is used by beneficial microflora with the release of organic acids that stimulate the maturation of intestinal cells and its peristalsis.

Lactose in human milk differs from lactose in cow's milk in its isomeric structure. While in human milk it is β-lactose, in cow's milk it is predominantly α-lactose. β-lactose differs from its isomer in bifidogenic properties and promotes the absorption of Ca, Mg, Mn, Zn. Due to the predominant content of lactose in breast milk, it has a low osmolarity, which is important for the normal absorption of nutrients.

Oligosaccharides. About 130 types of oligosaccharides have been identified, biological role Most of them have not yet been studied enough. Many of them are able to suppress the binding of toxins of viral and microbial origin to intestinal epithelial cells. All oligosaccharides are prebiotics, stimulating the growth of beneficial intestinal microflora.

Vitamins, minerals and trace elements

Content minerals in human milk is significantly lower than in the milk of most mammals, but provides all the necessary needs of the child’s body. The content of vitamins depends on the diet of the nursing mother. This is especially true water-soluble vitamins, for example, vitamin C. Vitamin D, although contained in breast milk, its amount is not able to fully satisfy the physiological need, so it is additionally introduced into the child’s diet.

Milk production process mammary glands called lactation. Human milk is a natural biological product and is the main factor in the adaptation of a newborn to extrauterine life. Its composition has not yet been fully deciphered, and discoveries in this area occur as new research methods are used. It is currently known that mother's milk is the equivalent of umbilical blood and carries not only nutrition for the baby, but also many protective, regulatory substances, growth and maturation factors, hormones and hormone-like compounds, etc. According to WHO research, mature breast milk contains hundreds of different components.

The difficulty in studying the qualitative and quantitative composition of breast milk lies in the fact that it is very variable during lactation and depends on many factors. Even in one mother, milk in different mammary glands differs in composition and changes from feeding to feeding, not to mention the entire lactation period. As we have already said, the main reason for these differences is the individual needs of each child, which change as he develops. Interesting facts are given in the WHO Bulletins (Feeding of children in the first year of life: physiological basis, 1989) - women who are breastfeeding twins, each child of which prefers a particular breast, sometimes notice different types of milk.

Now let's look at the main components of breast milk.

Milk is a complex aqueous emulsion containing fat droplets, proteins, carbohydrates, salts, vitamins, microelements and other substances. All components can be divided into nutrients that replenish the energy and plastic needs of the child’s body and non-nutrients necessary for maturation and growth, development, protection from infections, etc.

PROTEIN

The protein content of mature breast milk is approximately 1%. This is significantly lower than in the milk of other mammals. Proteins are represented by casein and whey fractions. Casein protein is synthesized directly in the mammary gland, and whey protein is filtered from the mother's blood. The ratio of these fractions in human milk is 20: 80 (30: 70), in cow's milk, on the contrary, the majority is represented by caseins 80: 20. During digestion, casein under the influence of gastric juice forms larger flakes than whey proteins and is therefore more difficult to absorb. Breast milk forms almost invisible flakes in the stomach, facilitating digestion and is quickly evacuated from the stomach. This makes it possible to frequently put the baby to the breast without fear of gastrointestinal overload and digestive disorders.

Whey proteins in human milk are mainly represented by alpha-lactoglobulin, an important component enzyme system in the synthesis of lactose. It should be noted that breast milk substitutes are made from cow's (goat's) milk and contain beta-lactoglobulin, which is a powerful allergen, as whey protein.

In human milk, more than high level free amino acids, among which the most important are cysteine ​​and taurine, since their synthesis in children early age difficult. Cysteine ​​is essential for the fetus and children born prematurely, and taurine is necessary for the maturation and development of the central nervous system, as it serves as a neurotransmitter and neuromodulator.

FATS

In human milk, fats are found in the form of microscopic globules, much smaller in size than in cow's milk. This is the most variable component, since the fat content ranges from 2% (in colostrum) to 4 - 4.5% (in mature milk). Interestingly, the concentration of fat in hind milk is 4 to 5 times higher than in fore milk and this acts as a satiety regulator. Therefore, the duration of feeding should not be regulated and may vary depending on the condition of the child. If the baby only feels thirsty, he satisfies it within 5-10 minutes with foremilk, which is poor in fat, and stops sucking, and, conversely, with a strong feeling of hunger, he can spend up to 1-1.5 hours at the breast. WHO studies have proven that children themselves regulate their energy saturation, but the mechanisms of this have not been clarified.

The fatty acids that make up breast milk are relatively stable in composition and are represented by 57% unsaturated and 42% saturated fatty acids. Long-chain polyunsaturated fatty acids are essential for myelination and maturation of the central nervous system, among which the most important are arachidonic and linolenic fatty acids. Their content in human milk is almost 4 times higher than in cow's milk. The presence of these fatty acids determines the synthesis of prostaglandins in the child’s gastrointestinal tract, which affect many functions that activate digestion and maturation of intestinal cells and thus the entire protective mechanism. Breast milk is rich in prostaglandins, while milk substitutes have none at all.

The main source of energy for the fetus is glucose, and for the newborn and infant- fats. They provide 35 - 50% of the daily energy requirement. Interestingly, only human milk and the milk of some primates contain enzymes that digest fat.

CARBOHYDRATES

The main carbohydrate component of human milk is lactose, otherwise called milk sugar. This sugar is specific only to milk and the largest amount is found in human milk (4% in colostrum and up to 7% in mature milk). Lactose is a disaccharide that, when broken down by the enzyme lactase, produces glucose and galactose. Lactase is found only in the gastrointestinal tract of mammals. Glucose is a source of energy, and galactose is used for the synthesis of galactopeptides necessary during the development of the central nervous system. In addition, lactose stimulates the formation of intestinal colonies of Lactobacillus bifidus.

Other components of breast milk carbohydrates - oligosaccharides, fructose, galactose, are contained in small quantities. One type of oligosaccharides is known as “bifidus factor”; it promotes the proliferation of beneficial microflora in the intestines and prevents the development of pathogenic ones.

VITAMINS

The content of vitamins in breast milk depends on the needs of the child, the mother’s nutrition, and the duration of lactation. In colostrum and early (fore) milk, most vitamins are found in higher concentrations than in mature and late (hind) milk. Therefore, before feeding, you should not express foremilk, which is rich in vitamins. According to modern research Vitamin D is found mainly in foremilk and is there in a water-soluble (inactive) form, which, as the child needs, is transformed into a fat-soluble (active) form.

Cases of vitamin deficiency in children on breastfeeding rare, even if the mother is a vegetarian. In the second year of life, vitamin deficiencies (particularly vitamin A) are more common in children who are weaned early than in those who continue to breastfeed.

MACRO AND MICROELEMENTS

Minerals in breast milk are contained in an easily digestible form (compounds), which ensures a high percentage of their absorption in the baby’s gastrointestinal tract. There are many other factors that improve absorption - certain proportions of minerals and vitamins, the presence of excipients that are found only in breast milk (lactoferrin), etc. Thus, the iron in human milk is absorbed by 70%, the iron in cow's milk by 30%, and the iron included in formulas by only 10%.

In order for a child who is on artificial feeding received a sufficient amount of minerals, their content in breast milk substitutes is significantly increased, which cannot but cause negative effects on the baby’s body.

Microelements in human milk are presented wide range, and how macronutrients differ significantly from those found in formulas. In conclusion, I would like to note that a breastfed child is less susceptible to deficiency or excess of macro- and microelements.

IMMUNE FACTORS

Mother's milk has a dual effect on the child's body. On the one hand, it itself has protective properties, on the other hand, it stimulates the development of the baby’s own immune system.

Immediately after birth, a huge number of microorganisms, the toxins they produce, and allergens enter the baby’s body. It’s hard to imagine how a still immature girl would cope immune system a newborn with such an attack, if not for mother's milk. Human milk, and especially colostrum, contains a huge number of protective factors such as immunoglobulins of class A, M, G, lysozyme and other enzymes, lactoferrin, bifidus factor, macrophages, lymphocytes, neutrophils, epithelial cells. Immunoglobulins, especially secretory immunoglobulin A, envelop the baby’s gastrointestinal tract and prevent pathogens from entering it. At the same time, the maturation of the intestinal epithelium and the production of digestive enzymes are stimulated.

The mother’s body is constantly in the process of producing antibodies against bacteria and viruses that enter her body. These antibodies pass into milk and protect the baby against many pathogens. Fragments of viruses also enter breast milk, stimulating the baby’s body’s sensitivity to them, resulting in effective immunization.

HORMONES

According to modern research, breast milk contains more than 20 types of hormones. Moreover, the concentration of some of them is several times higher than the concentration in the mother’s blood. Such hormones include oxytocin, prolactin, some sex hormones, prostaglandins, growth hormone, insulin, etc. Hormones thyroid gland contained in lower concentrations.

Thus, breast milk actively affects metabolism and various processes in the child’s body. Obviously, breast milk substitutes cannot have similar properties.

ENZYMES

Enzymes are one of the components of human milk. Most of them are multifunctional - they reflect the processes occurring in the mammary glands and are necessary for the development of the newborn. Many enzymes are found in colostrum in higher concentrations than in mature milk (for example, lysozyme).

It is not possible to introduce enzymes into mixtures.

OTHER SUBSTANCES

Human milk contains nucleotides involved in lipid metabolism, as well as numerous growth factors (epidermal growth factor, insulin-like growth factor, nervous tissue growth factor, human milk growth factor). Their role in child development has not yet been fully elucidated.

Composition (per 100 ml) of mature breast milk and cow's milk and recommendations on the composition of infant formula.

• Acceptable range of infant formula composition (one value indicates the minimum acceptable values).
• Genuine protein = 0.85g per 100ml (excluding non-protein nitrogen), although some non-protein nitrogen is used for the sustenance and physical development of infants.
• Iron in breast milk is characterized by high bioavailability, absorption is 50 - 70%.
• Iron in infant formula is characterized by low bioavailability, absorption is only 10%.

Immaturity gastrointestinal tract children infancy leads to the need for processing and consumption of nutrients in an easily digestible form. The best and most physiological food for a 1 year old child is only. Breastfeeding promotes normal growth and development of the child, increases his resistance to infections and much more.

What is unique about breast milk?

The uniqueness of breast milk is that it contains special substances that protect the baby’s body from various diseases. The baby receives mother's milk sterile and warm, which means the risk of diseases is reduced and the digestion process takes place in more favorable conditions.

The composition, properties of breast milk, its quantity changes throughout the entire lactation period, depending on the mother’s health, her diet, regimen, season, and the needs of her child. And, of course, every mother’s milk adapts to her baby. He will find everything he needs for growth and development in breast milk.

At the end of pregnancy and in the first 3-4 days after birth, it is secreted colostrum(colostrum) - thick, sticky liquid yellow, from 4-5 days - transition milk, from 2-3 weeks - mature milk.

Breast milk contains about 100 nutritional and biological active ingredients, characteristic to the human body. The most important ones are proteins, fats and carbohydrates. In breast milk they are in the ideal ratio for absorption by the child's body - 1: 3: 6, while in cow's milk - 1: 1: 1.

Among them, proteins and protein-containing components (hormones, enzymes, specific and nonspecific protective factors) have the greatest biological specificity.

Colostrum, unlike mature milk, is richer in proteins, salts and vitamins (for example, A, C, E, K, carotene), leukocytes and special colostrum bodies. But it contains less lactose, fat and water-soluble vitamins. Colostrum corpuscles are special cells of irregular shape with numerous small fatty inclusions. Proteins consist mainly of whey proteins - globulins and albumins; casein appears in transitional milk, from the 4-5th day of lactation and makes up only 1/5 of all proteins. There is less fat in colostrum than in transitional and mature milk. But it is higher in calorie content (see Table No. 1), which is very important in the first day of a child’s life.

Colostrum contains a high level of immunoglobulins and many other protective factors, which allows it to be considered not only a food product, but also a drug-modulator of child development.

Transition milk secreted from 4-5 days after birth. It is rich in fat, but its composition is already close to that of mature milk.

Mature milk appears by the end of 2 weeks. But during lactation its composition also changes. It can vary throughout the day and even during one feeding. So, at the beginning of feeding, the milk is thinner, but towards the end it is fattier and thicker.

In the baby's stomach, human milk coagulates into smaller flakes than mammalian milk. It is also important that it comes from mother to child at body temperature, almost sterile, containing bactericidal substances, in particular immunoglobulins, lysozyme, lactoferin, alpha-2-macroglobulin, etc. All the main ingredients of human milk are absolutely non-antigenic towards the child.

The protein of human milk consists mainly of delicate albumins and globulins, which are easily digested and absorbed by the child's body. But there is ten times less crude casein in breast milk than in cow's milk. The casein particles in human milk are so small that they form delicate flakes in the baby's stomach and are easily processed. Cow's milk also contains beta globulin - the main culprit allergic reactions, which is not found in breast milk (see table)

Characteristics of human and cow's milk proteins (g/100ml)

Protein is made up of amino acids. Amino acids are essential nutrients for the body. Of the 24 known amino acids, 8 are essential - threonine, valine, leucine, isoleucine, lysine, tryptophan, phenylalanine, methionine. And for children in the first year of life, histidine is also an essential amino acid. Human milk, for example, contains more taurine and cystine, and less methionine, compared to cow's milk

Cystine is necessary for fetal development and. Taurine serves as a neuromodulator for the development of the central nervous system, for the formation of bile salts, and for the absorption of fats. Children are not able to synthesize taurine, so it acts as an essential amino acid.

Fats in breast milk

Fats are one of the sources of energy for the body. Fats and their metabolic products participate in the formation of cell membranes, are carriers of fat-soluble vitamins A, D, E, K, participate in the formation of the nervous system, etc.

Human milk fats contain a large amount of fats, which are an indispensable plastic and energy material for the development of the child’s body. Human milk is stable in fatty acid composition and consists of 57% unsaturated and 42% saturated fatty acids, and is rich in phospholipids. The fats of human milk are much better absorbed in the baby's body compared to the fats of infant formula.

If there is a lack of fat in a child’s diet, growth slows down, immunity decreases, and pathological skin conditions develop. Excess of it inhibits secretion digestive glands, reduces the level of digestion and absorption of protein, disrupts phosphorus-calcium metabolism.

The digestibility of breast milk fat is very high - about 90%, covering about 50% daily requirement child in energy.

Miranda Kerr - famous Victoria's Secret model promotes breastfeeding

Carbohydrates in breast milk

The main carbohydrates in breast milk are lactose, which provides up to 40% of the energy needs of a growing baby's body, and small amounts of galactose, fructose, and oligosugars, such as bifidus factor. Lactose is a specific food product for infants, since the lactose enzyme is found only in young mammals.

Lactose promotes the absorption of calcium and iron, synthesis by intestinal microbes, stimulates the formation of intestinal lactobacilli, and inhibits the growth of E. coli. Cow's milk lactose, on the contrary, stimulates the growth of E. coli.

Breast milk - easily digestible source energy, creating a slightly acidic environment in the large intestine, which is destructive for putrefactive bacteria and beneficial for useful flora in the presence of bifidus factor.

Compound minerals, macro - and microelements in human milk are relatively better than in cow's milk. It contains more substances important for hematopoiesis: iron, copper, manganese, cobalt, etc., it is richer in enzymes and vitamins of groups B, A, C, etc.

Breast milk contains lactogenic hormones, hormone-like substances, growth factors and differentiation of cells and tissues, factors of specific and nonspecific protection against infections that are involved in the formation of a child (see table).

All these data indicate great benefit breast milk for the growth and development of a child in the first years of life. And before abandoning for reasons of aesthetic and psychological nature, rate positive aspects such feeding and weigh the pros and cons...

Your baby is what you eat

The proteins, fats, carbohydrates, vitamins and minerals that a baby gets from breast milk also don’t come out of nowhere. The source of all this abundance is. In order not to harm the child, you need to properly adjust your diet. It is especially important to adhere to the following principles:

1. Variety. Vegetables should predominate in a woman's diet. A little less - meat ( low-fat varieties), fish (boiled, 1-2 times a week) and bakery products, as well as dairy products (whole cow's milk is poorly absorbed by infants), fruits and berries. There should be a minimum of sweets, which cause proteins to stick together and can cause allergic reactions. If you really can’t do without sweets, let it be marshmallows, marshmallows or marmalade.
2. Food must be safe. Gastrointestinal problems in newborns are not uncommon. And one of preventive measures their occurrence is to control the quality of products consumed by a nursing mother. To avoid other hassles, you need to avoid extraactive ingredients, essential oils and salt. That is, such dishes and products as onions, garlic, broth, salted and pickled foods, canned food, smoked meats and sausages. It is undesirable to consume products fermentative: grapes, sweets, soda. You also need to exclude allergens: chocolate, cocoa, peanuts, crabs, shrimp, crayfish, eggs, tomatoes, strawberries, citrus fruits and other products that the mother’s body did not previously accept.
3. Stay hydrated. To do this, you need to monitor the amount of water consumed per day (at least 1 liter, including juices, soups, tea, etc.). But during the period of colostrum production (1-2 days after birth), the amount of water should not exceed a liter. Otherwise, with the beginning of lactation (on days 2-4), there will be too much milk and lactostasis or mastitis may develop.

Photos for social project"Your baby is what you eat"

BREAST MILK(syn. human milk) is a secretion from the mammary glands of a woman, which has species-biological specificity.

G. m. is the best view write for a child of the first year of life; it provides it full development. During the first days of lactation (see), colostrum is secreted (see), which by the 3-4th day loses its characteristic features and turns into the so-called transition milk. On the 2-3rd week. (rarely on the 4th) it acquires a constant composition and is called mature milk (Table 1).

Milk contains a large number of different substances. Human milk has some individual characteristics, depending on the nutritional pattern of the nursing woman. The composition of the blood mass of the same woman varies depending on the time of year ( lowest content protein, vitamin C in milk is observed in January - February), as well as whether a milk sample is taken before or after feeding the child (the fat content in 100 ml of milk before feeding the child ranges from 0.5 to 5.5 mg, and after feeding - from 3.7 to 9.7 mg). However, on average, there is a more or less constant composition of mature human milk throughout lactation (Table 2).

The quantity and ratio of the main ingredients that make up human milk provide optimal conditions for their digestion and absorption into the gastrointestinal tract. tract of the child. The difference between human milk and cow's milk (most often used to feed a baby in the absence of human milk) is quite significant. These differences are especially evident when diluting cow's milk for the preparation of infant formula (Table 3).

When breastfed with human milk, a share squirrel accounts for 8% of the total calorie content, when fed with cow's milk - 20%. When a child is breastfed naturally, fat accounts for 48% of the calorie content, and when feeding with formula milk it accounts for only 29-34%. The amount of milk sugar (lactose) when diluted with cow's milk is significantly reduced, and the calorie content from carbohydrates is provided by sucrose and other polysaccharides (see Feeding children). When breastfeeding, a physiological balance is established between mother and child when the child sucks out as much milk as he needs. This is due to changes in the composition of milk during feeding [Hall (V. Hall), 1975]. The mechanism that regulates appetite (and therefore the calorie content of food received) matures in a child by the 6th week. life [Fomon (S. J. Fomon) et al.].

Human milk proteins are ideal, biol, the value of which is 100%. Many different protein fractions have been isolated in G. m., among which 18 are identical to blood serum proteins. There is a difference in the ratio of individual protein fractions of human and cow's milk (Table 4).

Milk proteins differ in dispersion. Human milk proteins contain significantly more albumin, while cow's milk contains more caseinogen. The albumin/caseinogen ratio in human milk is 3:2, and in cow's milk it is 1:4. In addition, the casein molecule in human milk is smaller (30 nm) than in cow's milk (102 nm). When human milk curdles, due to the presence of a large amount of low molecular weight proteins and a lower content of calcium salts, small, delicate flakes are formed. This increases the surface area for gastric juices to act on, making human milk proteins easier to digest and absorb than cow's milk proteins.

Allergy to G. m. is an extremely rare phenomenon. There is still no indisputable evidence in favor of its existence (antibodies to G. m. have never been detected in children during natural feeding, as well as when administered intravenously in relatively large quantities).

In G. m. there are four classes of immunoglobulins - A, G, M and D (see Immunoglobulins). Most important has immunoglobulin A, which is secreted by breast cells (secretory immunoglobulin A). Due to the low proteolytic activity of gastric juice in children in the first months of life and the presence of a trypsin inhibitor in G. m., the destruction of immunoglobulins in the gastrointestinal tract is delayed. tract of the child, which ensures resistance of children of this age to infection, especially yellow-kish. diseases.

The amino acid composition of human and whole cow's milk proteins does not differ significantly (Table 5). However, when cow's milk is bred, these differences become significant.

In the body of children of the first 3 months. life due to the absence or low activity of liver cystathionine synthetase, the amino acid cystine cannot be synthesized (in children of this age it is one of the essential amino acids), therefore, a large amount of sulfur-containing amino acids (especially cystine) in G. m. provides more proper development child. Cow's milk protein is represented mainly by caseinogen, which is especially rich in aromatic amino acids, leucine and isoleucine (amino acids with strong branched chain). Therefore, overloading a child’s diet with protein can cause aminoacidemia (see), edges with the relative immaturity of the enzymatic systems involved in the metabolism of leucine and isoleucine, and imperfect renal function can adversely affect the development of c. n. With. The amount of residual nitrogen in human milk is composed of Ch. arr. from nitrogen of amino acids and urea and makes up Ve of the total nitrogen of milk. Ammonia is contained in negligible quantities.

Quantity fat in human and cow's milk is almost the same (3.5-3.8%), however, the fat of g. m. is absorbed much better (assimilation 95%) than the fat of cow's milk (absorption below 90%). This is explained different composition fat and fatty ones, as well as their stereochemical structure. The main component of milk fat is triglycerides, in which stearic acid is attached to glycerol in the outer position, and palmitic acid in the inner position. In children in the first months of life, the activity of pancreatic lipase is low, so the hydrolysis of fat and the dissolution of saturated fatty acids with a long carbon chain (stearic and palmitic) are especially difficult. When cow's milk fats are hydrolyzed, free fatty acids are formed, which are easily saponified with calcium and excreted from the intestines. This leads to irrational loss of not only fat, but also calcium during artificial feeding. G. m. is distinguished by a lower content of palmitic acid, which contributes to easier hydrolysis and complete absorption through pinocytosis (see) of the products of partial hydrolysis of fat - monoglycerides. Thus, the nutritional value of human milk fats, expressed by the coefficient of triglyceride absorption, is higher than that of cow's milk.

Women's and cow's milk are especially different in the composition of essential (irreplaceable) polyunsaturated fatty acids (Table 6).

A higher content of essential unsaturated fatty acids has a sparing effect on protein, increases its digestibility, and also promotes the manifestation of physiol, the action of vitamins (B 1, C) and increases the body's resistance to infections.

The content of linoleic acid, which cannot be synthesized in the body, in human milk is 5 times higher than in cow's milk. Its share in the total calorie content of G. m. is 5%, and in cow's milk - only 0.5%. Arachidonic acid, which is part of the nervous tissue, is also important. Human milk contains prostaglandins and their derivatives, which are integral part cell membranes.

A larger amount of lower saturated fatty acids in cow's milk fat compared to women's milk can irritate the gastrointestinal tract. tract, and myristic and lauric acids help increase blood cholesterol. The fats of human milk contain more phosphatides: colostrum - 6.1%, mature milk - 1.7% [according to Hilditch], which cause early and copious discharge bile, which promotes fat resorption in the upper parts of the small intestine. The average activity of lipase (tributyrase), the optimal action of the cut is at pH 7.0, in human milk is 20-25 times higher than in cow's milk. This promotes autolytic hydrolysis of human milk fat, starting from the stomach, and therefore easier digestion and absorption.

Milk contains: carbohydrates, the main of which is lactose, its amount in G. m. is on average 7.0-7.5%, and in cow's milk - 4.0-4.5%. The increase in sugar in mature breast milk compared to colostrum occurs primarily due to lactose (K. V. Orekhov). Along with beta-lactose, G. m. also contains other carbohydrates. Disaccharides, with their high calorie content, have lower osmolarity than monosaccharides. This promotes better absorption of nutrients in the small intestine. The monosaccharide galactose contained in lactose is used during the first weeks of life to synthesize galactosecerebrosides. At the same time, enriching infant formula with sucrose, consisting of glucose and fructose, in children in the first weeks of life is undesirable, since triose phosphate, formed during the metabolism of fructose, can increase acidosis due to increased formation of lactic acid. G. m. beta-Lactose, in contrast to the alpha-lactose of cow's milk, is absorbed more slowly in the small intestine and has time to reach the large intestine. This ensures the growth of bifidobacteria (see), which prevent the proliferation of putrefactive flora (antiputridity) of the intestine. The bifidogenicity-antiputridity of G. m. is 40 times higher than that of cows. This, along with beta-lactose, is facilitated by other oligosaccharides, as well as some human milk protein polypeptides and compounds associated with coenzyme A and calcium pantothenate.

G. m. contains the optimal amount mineral salts, and the ratio of their concentration ensures their best utilization. So, for example, in G. m. the ratio Ca/P is 2:1, which increases the coefficient of Ca absorption to 75%. This is important for the process of mineralization of the skeleton of a rapidly growing child during this period. At the same time, the content of Na, K and other mineral salts is relatively low, as a result of which there is no retention of osmotically active ions in the body of a child with low excretory function of the kidneys.

The ratio between cations and anions and their qualitative composition provide GM with an amphoteric reaction, which contributes to greater stability acid-base balance blood of breastfed children.

Quantity vitamins in breast milk depends on the season of the year and vitamin value food for a nursing mother. However, they are not enough to ensure the correct development of the child. The reserves of water-soluble vitamins received by the child in utero are limited and are quickly consumed and eliminated from the body in the first 2-4 weeks. life. Compared to cow's milk, human milk is richer in fat-soluble vitamins A, D, E. G. milk contains not only vitamin D3, but also its metabolites, which have a more pronounced effect on the absorption of calcium in the small intestine.

Colostrum, transitional and partially mature hemorrhoids contain important biologically active compounds (nonspecific protective factors in the form of lysozyme, substances that stimulate the complementary properties of the blood, virus-neutralizing antibodies, a heat-stable “antistaphylococcal” factor, as well as hormones and enzymes). Along with autolytic enzymes, aminotransferases, diastase, dehydrogenases, catalase, and others were found in G. m. The corticosteroid activity of G. m. is almost 3 times higher than that of cow. This is important, especially in the first days and weeks of life, since many systems are not functionally mature enough, and active immunity is only beginning to form during this period.

The mammary gland is a selective barrier for medicinal substances taken by the mother. However, alcohol, nicotine, caffeine, morphine, iodine, acetylsalicylic acid, arsenic, some sleeping pills (eg, Veronal) and various aromatic substances can pass into milk, which should be taken into account during lactation.

A nursing woman should express excess milk. Expressed milk is used to feed children deprived of mother's milk for one reason or another. At the collection points of G. m. it is mixed. The resulting donor milk has an average constant composition. As a result of transportation, storage, sterilization, etc., its biol properties change: immunoglobulins completely disappear, vitamin activity sharply decreases, biological destruction occurs active substances, partial protein denaturation. Milk may be contaminated.

Each woman's expressed milk delivered to the donor site must be analyzed. Its acidity and the possibility of dilution with water or animal milk are checked. To distinguish human milk from animal milk, a large number of tests have been proposed based on the difference in their pH. However, when human milk is contaminated with lactic acid bacteria, its pH decreases (fresh human milk has an acidity of 3-4° according to Turner), and it reacts as adulterated, although no cow's milk was added.

The Dahl-Berg test is based on the difference in physical properties of human and cow's milk proteins: 20% is added to milk chloride solution calcium, acidified with 0.1 N. HCl solution. After adding the methyl orange indicator, the test tube is immersed in a boiling bath. Cow's milk curdles instantly, but women's milk does not curdle. The reaction with CaCl 2 can be carried out without acidification.

A test can also be carried out with 0.01 N. sulfuric acid solution in the presence of Colthoff indicator (methyl orange + indigo carmine). If cow's milk (more than 10%) was added to human milk, casein settles to the bottom of the test tube and becomes colored green; human milk casein remains suspended.

Reaction E. 3. Umikov: human milk mixed with ammonia at room temperature gradually acquires a red-violet color. Heating milk to a temperature of 60-100° accelerates the appearance of color. Cow's milk mixed with ammonia does not give any color.

Table 1. Composition of colostrum, transitional and mature human milk in different terms lactation (%)

Table 2. Composition of human milk (average figures, according to various authors)

Table 3 Distribution of total calories between proteins, fats, carbohydrates in milk and infant formula (in%)

Table 4. RATIO OF SOME PROTEIN FRACTIONS IN WOMAN AND COW'S MILK (according to G. S. Korobkina, 1970)

Table 5. Amino acid composition of human and cow's milk proteins (according to FAO/WHO experts, 1966)

Table 6. Content of fatty acids in the fat of human and cow's milk as a percentage of the total amount of fat (according to G. S. Korobkina, 1970)

Bibliography: Vasilyeva L.P. and Gurvich D.B. Quantitative content of protein, fat, calcium, magnesium and phosphorus salts in human milk in the first week of lactation, Vopr. ocher mat. and children, vol. 12, no. 6, p. 65, 1967, bibliogr.; Boxes-on G.S. Products baby food, M., 1970, bibliogr.; Milk intolerance and nutritional programs, WHO Chronicle, vol. 26, JVe 11, p. 525, 1972; Orekhov K.V. On the metabolic adaptation of newborn children, Pediatrics, No. I, p. 41, 1973; Tour A. F. Directory on dietetics for young children, L., 1971, bibliogr.; Fomon S.J.a.o. Influence of formula concentration on caloric intake and growth of normal infants, Acta paediat. (Uppsala), v. 64, p. 172, 1975; Hall B. Changing composition of human milk and early development of an appetite control, Lancet, v. 1, p. 779, 1975.

A. V. Mazurin.

Breast milk in the best possible way satisfies the baby's needs for nutrients - proteins, fats, carbohydrates, vitamins and microelements. And the point here is not only in the amount of useful substances contained in it, but also in their compatibility with each other. The composition of breast milk adapts to individual characteristics each child, it changes as the baby grows and his needs change, and also depends on the time of day and the condition of the baby. So, at the end of pregnancy or in the first 3-4 days after birth, colostrum appears, then it is replaced by milk, which is called transitional milk, and from the 2-3rd week after birth, transitional milk turns into mature milk. How are they different from each other? Let's figure it out.

What is colostrum?

So, the first nutrition that a baby should receive after birth is colostrum. It is necessary for a smooth transition from feeding through the umbilical cord to breastfeeding. The composition of colostrum is unique and ideal for a newborn baby and is easily digestible. It is a thick, sticky, yellowish liquid. Very little of it is released - approximately from 10 to 100 ml (average 30 ml) per day. A child sucks out approximately 5–10 ml of colostrum per feeding. Many mothers are worried that by eating so little, the baby will remain hungry. Often they begin to feed the child with formula milk or supplement with water without a doctor’s recommendation. This cannot be done!

Firstly, healthy child A baby is born with a supply of water that protects its body from dehydration until milk comes in.

Secondly, if the baby drinks liquid or mixture, it creates a feeling of fullness in the stomach, and it begins to suck less often and weakly. This leads to insufficient intake of beneficial colostrum and affects further milk production. After all, in order for there to be a lot of milk, the breasts need frequent regular stimulation, which is provided by the baby’s sucking movements. This is precisely what signals the mother’s brain to increase the production of the hormones prolactin and oxytocin, which regulate the production and release of milk.

And thirdly, and this is the most important thing, nature has provided exactly such a volume of colostrum for the baby, which explains its physiological characteristics. The baby's kidneys and intestines are not yet ready for a large volume of fluid, so colostrum contains little water, which protects these organs from excess load. The volume of a newborn's stomach is very small, so the baby can eat only 5–10 ml at one feeding. But the small amount of colostrum that the baby sucks is compensated by its increased nutritional and energy value. The amount of nutrients necessary for the baby is provided mainly due to the high protein content: colostrum contains 3–5 times more protein than in mature milk. It is in an easily digestible form, does not require a large amount of digestive juices for digestion and does not cause tension in the gastrointestinal tract of the newborn. It should also be noted that colostrum is 2 times higher than mature milk in terms of essential amino acid content.

But colostrum contains less fat and carbohydrates (milk sugar - lactose) than mature milk. And this is justified. After all, in this way the load on the baby’s still immature enzymatic system is reduced.

The high concentration of special substances phosphatides in colostrum promotes the secretion of bile, uniform evacuation of fat from the stomach and its more active absorption in the upper parts of the small intestine. Colostrum also contains enzymes and hormones that activate digestive and metabolic processes in infants.

In addition, colostrum is different high content vitamin A, E, B12, ascorbic acid, carotene and retinol, which contribute to the development of the nervous system, muscle tissue and the retina of the baby's eyes. Thus, if a newborn baby is put to the breast on demand, colostrum fully meets his nutritional needs.

Composition of breast milk: transition milk

From the 4th–5th day after birth, transitional milk begins to be produced. At first it saves yellowish color(like colostrum), and it retains many of the colostrum components. Subsequently, the milk becomes white, the amount of protein in its composition decreases and the content of fat and carbohydrates increases. The breast increases in size, becomes dense, hot, and often painful. To facilitate this process, the mother should try to put the baby to the breast as often as possible, without limiting feeding time, so that he empties it well.

When does mature milk come?

From the 2-3rd week after birth, transitional milk turns into mature milk. It is conventionally divided into “front” and “rear” portions.

The baby receives foremilk at the beginning of feeding. It contains a lot of liquid, sugar (lactose) and protein, has a bluish color and is produced in larger quantities.

The “posterior” reaches the baby at the end of feeding and has a rich white due to the content of a large amount of fat, the concentration of which is 4–5 times higher than in the “front”.

Breast milk contains all the nutrients, vitamins and microelements a baby needs, and their content fully meets his needs.

Composition of breast milk

Water

Milk is approximately 87% water, so a breastfed baby does not need to give additional water.

Squirrels

Mature milk contains approximately 1% protein. Breast milk proteins are similar in qualitative composition to blood serum proteins (albumin and globulins), and therefore are easily absorbed by the child’s body. As the child gets older, the protein content in breast milk decreases. This is explained by the fact that the baby is already beginning to receive complementary foods, which also contain protein. Its excess intake causes increased load to the kidneys and liver.

The value of proteins in breast milk is determined by the presence of essential amino acids in them, which are not independently synthesized in the baby’s body. The most important of these are cysteine, methionine and taurine. Cysteine ​​plays important role in the formation of skin tissue, methionine is involved in the processing of fats and the synthesis of nucleic acids, taurine is necessary for the maturation and development of the nervous system and retina. Most of the proteins in human milk form the body's defenses, and thereby help the baby fight infections.

The child's immunity in the first months of life is mainly ensured by antibodies and special protective factors contained in mother's milk, which are proteins (lactoferrin, immunoglobulins and lysozyme). Their content in mature milk is less than in colostrum, but they still perform their protective function. Lactoferrin is involved in the binding and transport of iron in the body, in protection against infections, and also has anti-inflammatory and immunomodulatory activity. In addition, it is a strong activator of baby growth.

Carbohydrates

Carbohydrates in mature milk make up about 7%, and the main one is lactose (milk sugar). A large amount of lactose in breast milk stimulates the growth of normal intestinal microflora, thereby suppressing the proliferation of pathogenic microbes and protecting the baby from intestinal infections. In addition, lactose promotes the absorption of calcium and iron. Human milk contains not only lactose itself, but also a special enzyme for its breakdown - lactase. The enzyme is located mainly in the “back” portion of milk, so only those babies who have been at the breast for a long time can receive it. If the mother interrupts feeding ahead of time and the baby does not receive “hind” milk, rich in the enzyme lactase, then undigested lactose from the “front” portion of milk enters the large intestine, where it causes fermentation, gas formation, the baby begins to have a stomach ache, and the stool becomes liquid and foamy.

Fats

Mature milk contains up to 4.5% fat. The mechanisms of its absorption in infants are still immature, so breast milk contains the enzyme lipase, which breaks down fat. Polyunsaturated fatty acids - omega-3 and omega-6, which are part of breast milk - are in an optimal ratio of 5: 1 and are necessary for correct formation nervous system and intelligence of the baby.

Fats provide the baby's energy needs. The fat content of milk decreases as the baby grows. After 6 months, the baby’s growth rate and weight gain decrease, and he spends less energy (calories) on these processes.

Vitamins and microelements

Breast milk contains microelements necessary for the development of the baby - calcium, potassium, sodium, zinc, phosphorus, magnesium, iron, selenium, copper, as well as vitamins A, E, C, D.

In mature milk, compared to colostrum, the concentration of some vitamins decreases, but the amount of other important substances increases. For example, folic acid, which promotes the absorption of iron, and nicotinic acid, which helps the stomach and improves blood circulation.

Minerals are found in breast milk in such proportions that promote their better absorption and do not put additional stress on the baby’s liver and kidneys. For example, calcium is well absorbed due to the optimal ratio with phosphorus (2:1), and iron is absorbed by 50% (while only 5–10% from cow's milk).

Breast milk contains more than 15 types of hormones and the whole complex growth factors that influence the growth and proper development of a child. It is also important that human milk is completely devoid of allergenic properties. When breastfeeding, the baby gradually becomes accustomed to the foods that the mother eats, which reduces the risk of developing food allergies in the future, when he himself will use them.

Breastfeeding is called natural nutrition, and indeed, breast milk is the best that nature provides and that a mother can offer to her baby.

Properties of breast milk

In addition to its nutritional function, colostrum has a number of valuable properties:

• It has a mild laxative effect, which is due to the high content of magnesium in it. This contributes to the timely cleansing of the child’s intestines from meconium (original feces), the removal of bilirubin from the body along with feces, which, in turn, reduces the intensity and duration of physiological jaundice newborns, which develops in most babies.
• Colostrum provides immune protection child, as it contains a lot of immunoglobulins. The highest concentrations of these beneficial substances are found in colostrum immediately after the baby is born, so it is very important to put your baby to the breast within 30 minutes of birth.
• Immunoglobulins activate white blood cells (leukocytes), which cover the immature surface of the intestine, protecting it from harmful microbes. This is why colostrum is often called a child’s first vaccination.
• Colostrum is rich in growth factors that stimulate the development of the child's immature gastrointestinal tract, preparing it for the digestion and absorption of milk, preventing the development of allergies.
• Neurogrowth factor contained in colostrum promotes the development of the nervous system.

Why is breast milk the ideal food for a baby?

Breast milk is the ideal food for a breastfeeding baby because it meets the following requirements:

• is a balanced and easily digestible diet;
• meets the individual needs of each specific baby;
• ensures optimal physical and neuropsychic development of the child;
• protects the baby from various pathogenic microbes;
• does not cause allergies;
• promotes the development of normal intestinal microflora;
• contains a number of important biologically active substances, such as enzymes, hormones, immunoglobulins;
• always has the optimal temperature for the child;
• Forms a close, trusting relationship between mother and baby.