Breast milk (sometimes spelled as breastmilk) or mother's milk is
milk
Milk is a white liquid food produced by the mammary glands of lactating mammals. It is the primary source of nutrition for young mammals (including breastfeeding, breastfed human infants) before they are able to digestion, digest solid food. ...
produced by the
mammary glands
A mammary gland is an exocrine gland that produces milk in humans and other mammals. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in primates (for example, human ...
in the
breasts
The breasts are two prominences located on the upper ventral region of the torso among humans and other primates. Both sexes develop breasts from the same embryology, embryological tissues. The relative size and development of the breasts is ...
of women. Breast milk is the primary source of nutrition for newborn
infants, comprising fats, proteins, carbohydrates, and a varying composition of minerals and vitamins. Breast milk also contains substances that help protect an infant against infection and inflammation, such as
symbiotic bacteria and other microorganisms and
immunoglobulin A
Immunoglobulin A (IgA, also referred to as sIgA in its secretory form) is an antibody that plays a role in the immune function of mucous membranes. The amount of IgA produced in association with mucosal membranes is greater than all other ty ...
, whilst also contributing to the healthy development of the infant's
immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
and
gut microbiome
Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the g ...
.
Use and methods of consumption

The
World Health Organization
The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...
(WHO) and
UNICEF
UNICEF ( ), originally the United Nations International Children's Emergency Fund, officially United Nations Children's Fund since 1953, is an agency of the United Nations responsible for providing Humanitarianism, humanitarian and Development a ...
recommend
exclusive breastfeeding with breast milk for the first six months of an infant’s life. This period is followed by the incorporation of nutritionally adequate and safe complementary solid foods at six months, a stage when an infant’s nutrient and energy requirements start to surpass what breast milk alone can provide. Continuation of breastfeeding is recommended up to two years of age. This guidance is due to the protective benefits of breast milk, which include fewer infections such as diarrhea—a protection not afforded by
formula milk.
Breast milk constitutes the sole source of nutrition for exclusively breastfed newborns, supplying all necessary nutrients for infants up to six months. Beyond this age, breast milk continues to be a source of energy for children up to two years old, providing over half of a child's energy needs up to the age of one and a third of the needs between one and two years of age.
Despite the capability of most newborns to latch onto the mother's breast within an hour of birth, globally, sixty percent of infants are not breastfed within this crucial first hour. Breastfeeding within the first hour of life protects the newborn from acquiring infections and reduces risk of death during the neonatal period.
Alternatively, breast milk can be expressed using a
breast pump A breast pump is a mechanical device that Lactation, lactating women use to milking, extract milk from their breasts. They may be manual devices powered by hand or foot movements or automatic devices powered by electricity.
Breast pumps come in sev ...
and administered via
baby bottle
A baby bottle, nursing bottle, or feeding bottle is a bottle with a ''teat'' (also called a ''nipple'' in the US) attached to it, which creates the ability to drink via suckling. It is typically used by infants and young children, or if someone ...
, cup, spoon, supplementation drip system, or
nasogastric tube
Nasogastric intubation is a medical process involving the insertion of a plastic tube (nasogastric tube or NG tube) through the nose, down the esophagus, and down into the stomach. Orogastric intubation is a similar process involving the insertion ...
.
This method is especially beneficial for
preterm babies who may initially lack the ability to suck effectively. Using cups to feed expressed breast milk and other supplements results in improved breastfeeding outcomes in terms of both duration and extent, compared with traditional bottle and tube feeding.
For mothers unable to produce an adequate supply of breast milk, the use of
pasteurized donor human breast milk is a viable option. In the absence of pasteurized donor milk, commercial formula milk is recommended as a secondary alternative.
However, unpasteurized breast milk from a source other than the infant's mother, particularly when shared informally, carries the risk of
vertically transmitting bacteria, viruses (such as
HIV), and other microorganisms from the donor to the infant, rendering it an unsafe alternative.
Benefits
Breastfeeding offers health benefits to mother and child even after infancy. These benefits include proper heat production and adipose tissue development, a 73% decreased risk of
sudden infant death syndrome
Sudden infant death syndrome (SIDS), sometimes known as cot death or crib death, is the sudden unexplained death of a child of less than one year of age. Diagnosis requires that the death remain unexplained even after a thorough autopsy and ...
, increased
intelligence
Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. It can be described as t ...
, decreased likelihood of contracting
middle ear infections, cold and
flu resistance, a tiny decrease in the risk of
childhood leukemia, lower risk of childhood onset
diabetes
Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...
, decreased risk of
asthma
Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...
and
eczema
Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ...
,
decreased
dental problems,
decreased risk of
obesity
Obesity is a medical condition, considered by multiple organizations to be a disease, in which excess Adipose tissue, body fat has accumulated to such an extent that it can potentially have negative effects on health. People are classifi ...
later in life, and a decreased risk of developing
psychological disorders
A mental disorder, also referred to as a mental illness, a mental health condition, or a psychiatric disability, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. A mental disorder is ...
, including in
adopted children. In addition, feeding an infant breast milk is associated with lower insulin levels and higher leptin levels compared feeding an infant via
powdered-formula.
Many of the infection-fighting and immune system related benefits are associated with
human milk oligosaccharides.
Breastfeeding also provides health benefits for the mother. It assists the uterus in returning to its pre-pregnancy size and reduces post-partum bleeding, through the production of oxytocin (see Production). Breastfeeding can also reduce the risk of
breast cancer
Breast cancer is a cancer that develops from breast tissue. Signs of breast cancer may include a Breast lump, lump in the breast, a change in breast shape, dimpling of the skin, Milk-rejection sign, milk rejection, fluid coming from the nipp ...
later in life.
Lactation
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The process ...
may also reduce the risk for both mother and infant from both types of diabetes. Lactation may protect the infant from specifically developing Type 2 diabetes, as studies have shown that bioactive ingredients in human breast milk could prevent excess weight gain during childhood via contributing to a feeling of energy and satiety. The lower risk of child-onset diabetes may be more applicable to infants who were born from diabetic mothers.
The reason is that while breastfeeding for at least the first six months of life minimizes the risk of type 1 diabetes from occurring in the infant, inadequate breastfeeding in an infant prenatally exposed to diabetes was associated with a higher risk of the child developing diabetes later.
There are arguments that breastfeeding may contribute to protective effects against the development of type 1 diabetes because the alternative of bottle-feeding may expose infants to unhygienic feeding conditions.
Though it is almost universally prescribed, in some countries during the 1950s, the practice of
breastfeeding
Breastfeeding, also known as nursing, is the process where breast milk is fed to a child. Infants may suck the milk directly from the breast, or milk may be extracted with a Breast pump, pump and then fed to the infant. The World Health Orga ...
went through a period where it was out of vogue and the use of
infant formula
Infant formula, also called baby formula, simply formula (American English), formula milk, baby milk, or infant milk (British English), is a manufactured food designed and marketed for feeding to babies and infants under 12 months of age, ...
was considered superior to breast milk. However, it is since universally recognized that there is no commercial formula that can adequately substitute for breast milk. In addition to the appropriate amounts of
carbohydrate
A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...
,
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
, and
fat
In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food.
The term often refers specif ...
, breast milk provides
vitamin
Vitamins are Organic compound, organic molecules (or a set of closely related molecules called vitamer, vitamers) that are essential to an organism in small quantities for proper metabolism, metabolic function. Nutrient#Essential nutrients, ...
s,
minerals
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): M ...
,
digestive enzyme
Digestive enzymes take part in the chemical process of digestion, which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes ...
s,
and
hormones
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physiology and behavior. Hormones a ...
.
Breast milk also contains antibodies and lymphocytes from the mother that may help the baby resist infections. The immune function of breast milk is individualized, as the mother, through her touching and taking care of the baby, comes into contact with pathogens that colonize the baby, and, as a consequence, her body makes the appropriate antibodies and immune cells.
At around four months of age, the internal iron supplies of the infant, held in the hepatic cells of the liver, are exhausted. The
American Academy of Pediatrics
The American Academy of Pediatrics (AAP) is the largest professional association of pediatricians in the United States. It is headquartered in Itasca, Illinois, and maintains an office in Washington, D.C. The AAP has published hundreds of poli ...
recommends that at this time that an iron supplement should be introduced. Other health organisations such as the
NHS
The National Health Service (NHS) is the term for the publicly funded health care, publicly funded healthcare systems of the United Kingdom: the National Health Service (England), NHS Scotland, NHS Wales, and Health and Social Care (Northern ...
in the
UK have no such recommendation.
Breast milk contains less iron than formula, but the iron is more
bioavailable
In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation.
By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...
as
lactoferrin
Lactoferrin (LF), also known as lactotransferrin (LTF), is a multifunctional protein of the transferrin family. Lactoferrin is a globular proteins, globular glycoprotein with a molecular mass of about 80 Atomic mass unit, kDa that is widely repre ...
, which carries more safety for mothers and children than ferrous sulphate.
Both the AAP
and the NHS recommend
vitamin D
Vitamin D is a group of structurally related, fat-soluble compounds responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, along with numerous other biological functions. In humans, the most important compo ...
supplementation for breastfed infants.
Vitamin D can be synthesised by the infant via exposure to sunlight; however, many infants are deficient due to being kept indoors or living in areas with insufficient sunlight. Formula is supplemented with vitamin D for this reason.
Production
Under the influence of the hormones
prolactin
Prolactin (PRL), also known as lactotropin and mammotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secr ...
and
oxytocin
Oxytocin is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. Present in animals since early stages of evolution, in humans it plays roles in behavior that include Human bonding, ...
, women produce milk after
childbirth
Childbirth, also known as labour, parturition and delivery, is the completion of pregnancy, where one or more Fetus, fetuses exits the Womb, internal environment of the mother via vaginal delivery or caesarean section and becomes a newborn to ...
to feed the
baby
In common terminology, a baby is the very young offspring of adult human beings, while infant (from the Latin word ''infans'', meaning 'baby' or 'child') is a formal or specialised synonym. The terms may also be used to refer to Juvenile (orga ...
. The initial milk produced is referred to as
colostrum
Colostrum (, of unknown origin) is the first form of milk produced by the mammary glands of humans and other mammals immediately following delivery of the newborn. Animal colostrum may be called beestings, the traditional word from Old English ...
, which is high in the
immunoglobulin
An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...
IgA, which coats the
gastrointestinal tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...
. This helps to protect the newborn until its own
immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
is functioning properly. It also creates a mild laxative effect, expelling
meconium
Meconium is the earliest stool of a mammalian infant resulting from defecation. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the uterus: intestinal epithelial cells, lanugo, mucus, am ...
and helping to prevent the build-up of
bilirubin
Bilirubin (BR) (adopted from German, originally bili—bile—plus ruber—red—from Latin) is a red-orange compound that occurs in the normcomponent of the straw-yellow color in urine. Another breakdown product, stercobilin, causes the brown ...
(a contributory factor in
jaundice
Jaundice, also known as icterus, is a yellowish or, less frequently, greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving ...
). Male lactation can occur; the production or administration of the hormone prolactin is necessary to induce lactation (see
male lactation).
Actual inability to produce enough milk is rare, with studies showing that mothers from malnourished regions still produce amounts of milk of similar quality to that of mothers in developed countries. There are many reasons a mother may
not produce enough breast milk. Some of the most common reasons are an improper latch (i.e., the baby does not connect efficiently with the nipple), not nursing or pumping enough to meet supply, certain medications (including estrogen-containing
hormonal contraceptives), illness, and dehydration. A rarer reason is
Sheehan's syndrome, also known as postpartum
hypopituitarism, which is associated with prolactin deficiency and may require hormone replacement.
The amount of milk produced depends on how often the mother is nursing and/or
pumping: the more the mother nurses her baby or pumps, the more milk is produced.
It is beneficial to nurse when the baby wants to nurse rather than on a schedule. A
Cochrane review
Cochrane is a British international charitable organisation formed to synthesize medical research findings to facilitate evidence-based choices about health interventions involving health professionals, patients and policy makers. It includes ...
came to the conclusion that a greater volume of milk is expressed whilst listening to relaxing audio during breastfeeding, along with warming and massaging of the breast prior to and during feeding. A greater volume of milk expressed can also be attributed to instances where the mother starts pumping milk sooner, even if the infant is unable to breastfeed.
Sodium
Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...
concentration is higher in hand-expressed milk, when compared with the use of manual and electric pumps, and fat content is higher when the breast has been massaged, in conjunction with listening to relaxing audio. This may be important for
low birthweight infants.
If pumping, it is helpful to have an electric, high-grade pump so that all of the milk ducts are stimulated.
Galactagogues increase milk supply, although even herbal variants carry risks. Non-pharmaceutical methods should be tried first, such as pumping out the mother's breast milk supply often, warming or massaging the breast, as well as starting milk pumping earlier after the child is born if they cannot drink milk at the breast.
Composition
Breast milk contains fats, proteins, carbohydrates (including lactose and human milk oligosaccharides), and a varying composition of minerals and vitamins. The composition changes over a single feed as well as over the period of lactation.
Changes are particularly pronounced in
marsupial
Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...
s.

During the first few days after delivery, the mother produces
colostrum
Colostrum (, of unknown origin) is the first form of milk produced by the mammary glands of humans and other mammals immediately following delivery of the newborn. Animal colostrum may be called beestings, the traditional word from Old English ...
. This is a thin yellowish fluid that is the same fluid that sometimes leaks from the breasts during pregnancy. It is rich in protein and antibodies that provide passive immunity to the baby (the baby's immune system is not fully developed at birth). Colostrum also helps the newborn's digestive system to grow and function properly.
Colostrum will gradually change to become mature milk. In the first 3–4 days it will appear thin and watery and will taste very sweet; later, the milk will be thicker and creamier. Human milk quenches the baby's thirst and hunger and provides the proteins, sugar, minerals, and antibodies that the baby needs.
In the 1980s and 1990s, lactation professionals (De Cleats) used to make a differentiation between foremilk and hindmilk. But this differentiation causes confusion as there are not two types of milk. Instead, as a baby breastfeeds, the fat content very gradually increases, with the milk becoming fattier and fattier over time.
The level of
Immunoglobulin A
Immunoglobulin A (IgA, also referred to as sIgA in its secretory form) is an antibody that plays a role in the immune function of mucous membranes. The amount of IgA produced in association with mucosal membranes is greater than all other ty ...
(IgA) in breast milk remains high from day 10 until at least 7.5 months post-partum.
Human milk contains 0.8–0.9% protein, 4.5% fat, 7.1% carbohydrates, and 0.2% ash (minerals). Carbohydrates are mainly
lactose
Lactose is a disaccharide composed of galactose and glucose and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from (Genitive case, gen. ), the Latin word for milk, plus the suffix ''-o ...
; several lactose-based oligosaccharides (also called
human milk oligosaccharides) have been identified as minor components. The fat fraction contains specific
triglycerides
A triglyceride (from ''wikt:tri-#Prefix, tri-'' and ''glyceride''; also TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids.
Triglycerides are the main constituents of body fat in humans and oth ...
of
palmitic and
oleic acid
Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic acid is cl ...
(O-P-O triglycerides), and also lipids with trans bonds (see:
trans fat
Trans fat is a type of unsaturated fat that occurs in foods. Small amounts of trans fats occur naturally, but large amounts are found in some processed foods made with partially hydrogenated oils. Because consumption of trans fats is associated ...
). The lipids are
vaccenic acid, and
conjugated linoleic acid
Conjugated linoleic acids (CLA) are a family of isomers of linoleic acid. In principle, 28 isomers are possible. CLA is found mostly in the meat and dairy products derived from ruminants. The two C=C double bonds are conjugated (i.e., separated ...
(CLA) accounting for up to 6% of the human milk fat.
The principal proteins are alpha-
lactalbumin
Lactalbumin, also known as "whey protein", is the albumin contained in milk and obtained from whey. Lactalbumin is found in the milk of many mammals. There are alpha
Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet ...
,
lactoferrin
Lactoferrin (LF), also known as lactotransferrin (LTF), is a multifunctional protein of the transferrin family. Lactoferrin is a globular proteins, globular glycoprotein with a molecular mass of about 80 Atomic mass unit, kDa that is widely repre ...
(apo-lactoferrin), IgA,
lysozyme
Lysozyme (, muramidase, ''N''-acetylmuramide glycanhydrolase; systematic name peptidoglycan ''N''-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside hydrolase ...
, and
serum albumin
Serum albumin, often referred to simply as blood albumin, is an albumin (a type of globular protein) found in vertebrate blood. Human serum albumin is encoded by the ''ALB'' gene. Other mammalian forms, such as bovine serum albumin, are chem ...
. In an acidic environment such as the
stomach
The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...
, alpha-lactalbumin
unfolds into a different form and binds
oleic acid
Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic acid is cl ...
to form a complex called
HAMLET
''The Tragedy of Hamlet, Prince of Denmark'', often shortened to ''Hamlet'' (), is a Shakespearean tragedy, tragedy written by William Shakespeare sometime between 1599 and 1601. It is Shakespeare's longest play. Set in Denmark, the play (the ...
that kills
tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
cells. This is thought to contribute to the protection of breastfed babies against cancer.
Non-protein nitrogen-containing compounds, making up 25% of the milk's nitrogen, include
urea
Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest am ...
,
uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the Chemical formula, formula C5H4N4O3. It forms ions and salts known as urates and acid urates, such as ammonium acid urate. Uric acid is a product of the meta ...
,
creatine
Creatine ( or ) is an organic compound with the nominal formula . It exists in various tautomers in solutions (among which are neutral form and various zwitterionic forms). Creatine is found in vertebrates, where it facilitates recycling of ...
,
creatinine
Creatinine (; ) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass).
Biological relevance
Serum creatinine (a blood measurement) is an impor ...
,
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...
s, and
nucleotide
Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...
s. Breast milk has
circadian
A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (is entrai ...
variations; some of the nucleotides are more commonly produced during the night, others during the day.
Mother's milk has been shown to supply
endocannabinoid
Cannabinoids () are several structural classes of compounds found primarily in the ''Cannabis'' plant or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tetrahydrocannabinol (THC) (delta-9-THC), the primary psychoact ...
s (the natural neurotransmitters that
cannabis
''Cannabis'' () is a genus of flowering plants in the family Cannabaceae that is widely accepted as being indigenous to and originating from the continent of Asia. However, the number of species is disputed, with as many as three species be ...
simulates)
2-arachidonoylglycerol,
anandamide
Anandamide (ANA), also referred to as ''N''-arachidonoylethanolamine (AEA) is a fatty acid neurotransmitter belonging to the fatty acid derivative group known as N-acylethanolamine (NAE). Anandamide takes its name from the Sanskrit word ''ananda ...
,
oleoylethanolamide,
palmitoylethanolamide
Palmitoylethanolamide (PEA) is an endogenous fatty acid amide, and lipid modulator.
A main target of PEA is proposed to be the peroxisome proliferator-activated receptor alpha (PPAR-α). PEA also has affinity to cannabinoid-like G-coupled recept ...
,
N-arachidonoyl glycine,
eicosapentaenoyl ethanolamide,
docosahexaenoyl ethanolamide,
N-palmitoleoyl-ethanolamine,
dihomo-γ-linolenoylethanolamine,
N-stearoylethanolamine,
prostaglandin F2alpha ethanolamides
and prostaglandin F2 ethanolamides,
Palmitic acid esters of hydroxy-stearic acids (PAHSAs). They may act as an appetite stimulant, but they also regulate appetite so infants do not eat too much. That may be why formula-fed babies have a higher caloric intake than breastfed babies.
Breast milk is not
sterile
Sterile or sterility may refer to:
*Asepsis, a state of being free from biological contaminants
* Sterile (archaeology), a sediment deposit which contains no evidence of human activity
*Sterilization (microbiology), any process that eliminates or ...
and has
its own microbiome, but contains as many as 600 different species of
various bacteria, including beneficial ''
Bifidobacterium breve'', ''B. adolescentis'', ''B. longum'', ''B. bifidum'', and ''B. dentium'', which contribute to colonization of the infant gut. As a result, it can be defined as a probiotic food, depending on how one defines "
probiotic
Probiotics are live microorganisms that provide health benefits when consumed, generally by improving or restoring the microbiota in the gut. Probiotics are considered generally safe to consume, but may cause bacteria– host interactions ...
". Breast milk also contains a variety of
somatic cell
In cellular biology, a somatic cell (), or vegetal cell, is any biological cell forming the body of a multicellular organism other than a gamete, germ cell, gametocyte or undifferentiated stem cell. Somatic cells compose the body of an organism ...
s and
stem cell
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can change into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell ...
s and the proportion of each cell type differs from individual to individual.
The somatic cells are mainly
lactocytes and
myoepithelial cell
Myoepithelial cells (sometimes referred to as myoepithelium) are cells usually found in glandular epithelium as a thin layer above the basement membrane but generally beneath the lumen (anatomy), luminal cells. These may be positive for ACTA2, alph ...
s derived from the mother's mammary glands. The stem cells found in human breast milk have been shown to be able to differentiate into a variety of other cells involved in the production of bodily
tissues and a small proportion of these cross over the nursing infant's intestinal tract into the bloodstream to reach certain organs and transform into fully functional cells. Because of its diverse population of cells and multifarious functions, researchers have argued that breast milk should be considered a living tissue.
Breast milk contains a unique type of sugars,
human milk oligosaccharides (HMOs), which were not present in traditional infant formula, however they are increasing added by many manufacturers. HMOs are not digested by the infant but help to make up the
intestinal flora. They act as
decoy receptors that block the attachment of disease causing
pathogens
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.
The term ...
, which may help to prevent infectious diseases. They also alter
immune cell
White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cell (biology), cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood c ...
responses, which may benefit the infant. As of 2015 more than a hundred different HMOs have been identified; both the number and composition vary between women and each HMO may have a distinct functionality.
The breast milk of diabetic mothers has been shown to have a different composition from that of non-diabetic mothers. It may contain elevated levels of glucose and insulin and decreased polyunsaturated fatty acids. A dose-dependent effect of diabetic breast milk on increasing language delays in infants has also been noted, although doctors recommend that diabetic mothers breastfeed despite this potential risk.
Women
breastfeeding
Breastfeeding, also known as nursing, is the process where breast milk is fed to a child. Infants may suck the milk directly from the breast, or milk may be extracted with a Breast pump, pump and then fed to the infant. The World Health Orga ...
should consult with their physician regarding substances that can be unwittingly passed to the infant via breast milk, such as
alcohol
Alcohol may refer to:
Common uses
* Alcohol (chemistry), a class of compounds
* Ethanol, one of several alcohols, commonly known as alcohol in everyday life
** Alcohol (drug), intoxicant found in alcoholic beverages
** Alcoholic beverage, an alco ...
, viruses (
HIV or
HTLV-1), or medications. Even though most infants infected with HIV contract the disease from breastfeeding, most infants that are breastfed by their HIV positive mothers never contract the disease.
While this paradoxical phenomenon suggests that the risk of HIV transmission between an HIV positive mother and her child via breastfeeding is small, studies have also shown that feeding infants with breast milk of HIV-positive mothers can actually have a preventative effect against HIV transmission between the mother and child.
This inhibitory effect against the infant contracting HIV is likely due to unspecified factors exclusively present in breast milk of HIV-positive mothers.
Most women that do not breastfeed use
infant formula
Infant formula, also called baby formula, simply formula (American English), formula milk, baby milk, or infant milk (British English), is a manufactured food designed and marketed for feeding to babies and infants under 12 months of age, ...
, but breast milk donated by volunteers to human milk banks can be obtained by prescription in some countries. In addition, research has shown that women who rely on infant formula could minimize the gap between the level of immunity protection and cognitive abilities a breastfed child benefits from versus the degree to which a bottle-fed child benefits from them. This can be done by supplementing formula-fed infants with bovine
milk fat globule membrane
Milk fat globule membrane (MFGM) is a complex and unique structure composed primarily of lipids and proteins that surrounds milk fat globule secreted from the milk producing cells of humans and other mammals. It is a source of multiple bioactive co ...
s (MFGM) meant to mimic the positive effects of the MFGMs which are present in human breast milk.
Storage of expressed breast milk

Expressed breast milk can be
stored.
Lipase
In biochemistry, lipase ( ) refers to a class of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; howe ...
may cause thawed milk to taste soapy or rancid due to milk fat breakdown. It is still safe to use, and most babies will drink it. Scalding it will prevent rancid taste at the expense of antibodies. It should be stored with airtight seals. Some plastic bags are designed for storage periods of less than 72 hours. Others can be used for up to 12 months if frozen. This table describes safe storage time limits.
Comparison to other milks
All
mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
ian species produce milk, but the composition of milk for each species varies widely and other kinds of milk are often very different from human breast milk. As a rule, the milk of mammals that nurse frequently (including human babies) is less rich, or more watery, than the milk of mammals whose young nurse less often. Human milk is noticeably thinner and sweeter than cow's milk.
Whole cow's milk contains too little
iron
Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...
,
retinol
Retinol, also called vitamin A1, is a fat-soluble vitamin in the vitamin A family that is found in food and used as a dietary supplement. Retinol or other forms of vitamin A are needed for vision, cellular development, maintenance of skin and ...
,
vitamin E
Vitamin E is a group of eight compounds related in molecular structure that includes four tocopherols and four tocotrienols. The tocopherols function as fat-soluble antioxidants which may help protect cell membranes from reactive oxygen speci ...
,
vitamin C
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription di ...
,
vitamin D
Vitamin D is a group of structurally related, fat-soluble compounds responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, along with numerous other biological functions. In humans, the most important compo ...
,
unsaturated fat
An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is Monounsaturated fat, monounsaturated if it contains one double bond, and polyunsaturated fat, polyunsaturated i ...
s or essential
fatty acid
In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
s for human babies.
Whole cow's milk also contains too much
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
,
sodium
Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...
,
potassium
Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
,
phosphorus
Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...
and chloride which may put a strain on an infant's immature kidneys. In addition, the proteins, fats and calcium in whole cow's milk are more difficult for an infant to digest and absorb than the ones in breast milk.
The composition of marsupial and monotreme milk contains essential nutrients, growth factors and immunological properties to support the development of joeys and puggles.
Note: Milk is generally fortified with vitamin D in the U.S. and Canada. Non-fortified milk contains only 2 IU per 3.5 oz.
Effects of medications and other substances on milk content
Almost all medicines, or drugs, pass into breastmilk in small amounts by a concentration gradient.
The amount of the drug bound by maternal plasma proteins, the size of the drug molecule, the pH and/or pKa of the drug, and the lipophilicity of the drug all determine whether and how much of the drug will pass into breastmilk.
Medications that are mostly non-protein bound, low in molecular weight, and highly lipid-soluble are more likely to enter the breast milk in larger quantities.
Some drugs have no effect on the baby and can be used whilst breastfeeding, while other medications may be dangerous and harmful to the infant.
Some medications considered generally safe for use by a breastfeeding mother, with a doctor’s or pharmacist’s advice, include simple analgesics or pain killers such as Paracetamol, paracetamol/acetaminophen, anti-hypertensives such as the ACE inhibitor, ACE-inhibitors enalapril and captopril, anti-depressants of the SSRI and SNRI classes, and medications for gastroesophageal reflux such as omeprazole and ranitidine.
Conversely, there are medications that are known to be toxic to the baby and thus should not be used in breastfeeding mothers, such as chemotherapeutic agents which are cytotoxic like cyclosporine,
immunosuppressants like methotrexate,
amiodarone, or lithium.
Furthermore, drugs of abuse, such as cocaine, amphetamines, heroin, and marijuana cause adverse effects on the infant during breastfeeding. Adverse effects include seizures, tremors, restlessness, and diarrhea.
To reduce infant exposure to medications used by the mother, use topical therapy or avoid taking the medication during breastfeeding times when possible.
Hormonal products and combined oral contraceptives should be avoided during the early postpartum period as they can interfere with lactation.
There are some medications that may stimulate the production of breast milk. These medications may be beneficial in cases where women with hypothyroidism may be unable to produce milk.
A Cochrane review looked at the drug domperidone (10 mg three times per day) with results showing a significant increase in volume of milk produced over a period of one to two weeks. However, another review concluded little evidence that use of domperidone and metoclopramide to enhance milk supply works. Instead, non-pharmacological approaches such as support and more frequent breastfeeding may be more efficacious.
Finally, there are other substances besides medications that may appear in breast milk. Alcohol (drug), Alcohol use during pregnancy carries a significant risk of serious birth defects, but consuming alcohol after the birth of the infant is considered safe.
High caffeine intake by breastfeeding mothers may cause their infants to become irritable or have trouble sleeping.
A meta-analysis has shown that breastfeeding mothers who smoke expose their infants to nicotine, which may cause respiratory illnesses, including otitis media in the nursing infant.
Market
There is a commercial Market (economics), market for human breast milk, both in the form of a wet nurse service and as a milk product.
As a product, breast milk is exchanged by human milk banks, as well as directly between milk donors and customers as mediated by websites on the internet. Human milk banks generally have standardized measures for screening donors and storing the milk, sometimes even offering pasteurization, while milk donors on websites vary in regard to these measures. A study in 2013 came to the conclusion that 74% of breast milk samples from providers found from websites were colonized with gram-negative bacteria or had more than 10,000 colony-forming units/mL of aerobic bacteria.
Bacterial growth happens during transit.
According to the FDA, bad bacteria in food ''at room temperature'' can double every 20 minutes.
Human milk is considered to be healthier than cow's milk and infant formula when it comes to feeding an infant in the first six months of life, but only under extreme situations do international health organizations support feeding an infant breast milk from a healthy wet nurse rather than that of its biological mother.
One reason is that the unregulated breast milk market is fraught with risks, such as drugs of abuse and prescription medications being present in donated breast milk.
The transmission of these substances through breast milk can do more harm than good when it comes to the health outcomes of the infant recipient.
Fraud
In the United States, the online marketplace for breast milk is largely unregulated and the high premium has encouraged food fraud.
Human breast milk may be diluted with other liquids to increase volume including cow’s milk, soy milk, and water, thus undermining its health benefits.
A 2015 CBS article cites an editorial led by Dr. Sarah Steele in the ''Journal of the Royal Society of Medicine'', in which they say that "health claims do not stand up clinically and that Raw milk, raw human milk purchased online poses many health risks." CBS found a study from the Center for Biobehavioral Health at Nationwide Children's Hospital in Columbus, Ohio, Columbus that "found that 11 out of 102 breast milk samples purchased online were actually blended with cow's milk." The article also explains that milk purchased online may be improperly sanitized or stored, so it may contain food-borne illness and infectious diseases such as hepatitis and
HIV.
Consumption by adults
Restaurants and recipes
A minority of people, including restaurateurs Hans Lochen of Switzerland and Daniel Angerer of Austria, who operates a restaurant in New York City, have used human breast milk, or at least advocated its use, as a substitute for cow's milk in dairy products and food recipes. An icecreamist in London's Covent Garden, The Licktators, started selling an ice cream named Baby Gaga in February 2011. Each serving cost £14. All the milk was donated by a Mrs Hiley who earned £15 for every 10 ounces and called it a "great recession beater". The ice cream sold out on its first day. Despite the success of the new flavour, the Westminster Council officers removed the product from the menu to make sure that it was, as they said, "fit for human consumption." Tammy Frissell-Deppe, a family counsellor specialized in attachment parenting, published a book, titled ''A Breastfeeding Mother's Secret Recipes'', providing a lengthy compilation of detailed food and beverage recipes containing human breast milk. Human breast milk is not produced or distributed industrially or commercially, because the use of human breast milk as an adult food is considered unusual to the majority of cultures around the world, and most disapprove of such a practice.
In Costa Rica, there have been trials to produce human cheese, and custard from human milk, as an alternative to weaning.
Clínica busca cómo hacer queso de leche materna
'', Nación, 17 June 2007
Bodybuilders
While there is no scientific evidence that shows that breast milk is advantageous for adults, according to several 2015 news sources, breast milk is being used by bodybuilders for its nutritional value. In a February 2015 ABC News (United States), ABC News article, one former competitive body builder said, "It isn't common, but I've known people who have done this. It's certainly talked about quite a bit on the bodybuilding forums on the Internet." Calling bodybuilders "a strange breed of individuals", he said, "Even if this type of thing is completely unsupported by research, they're prone to gym lore and willing to give it a shot if there is any potential effect." At the time the article was written, in the U.S., the price of breast milk procured from milk banks that pasteurize the milk, and have expensive quality and safety controls, was about , and the price in the alternative market online, bought directly from mothers, ranges from , compared to cow's milk at about .
Erotic lactation
For sexual purposes, some couples have decided to Lactation#Without pregnancy, induced_lactation, relactation, induce lactation outside a pregnancy through a practice called "Erotic lactation".
Breast milk contamination
Breast milk is oftentimes used as an environmental bioindicator given its ability to accumulate certain chemicals, including organochlorine pesticides. Research has found that certain organic contaminants such as Polychlorinated biphenyl, PCBs, organochlorine pesticides, Polychlorinated dibenzodioxins, PCDDs, Polybrominated diphenyl ethers, PBDEs, and DDT can contaminate breastmilk.
According to research done in 2002, the levels of the organochlorine pesticides, PCBs, and dioxins have declined in breast milk in countries where these chemicals have been banned or otherwise regulated, while levels of PBDEs are rising.
[
]
Pesticide contamination in breastmilk
Pesticides and other toxic substances bioaccumulate; i.e., creatures higher up the food chain will store more of them in their body fat. This is an issue in particular for the Inuit, whose Inuit diet, traditional diet is predominantly meat. Studies are looking at the effects of polychlorinated biphenyls and persistent organic pollutants in the body; the breast milk of Inuit mothers is extraordinarily high in toxic compounds.
The CDC has provided some resources for breastfeeding mothers to reference for safe medication use, includin
LactMed
Mother to Baby
an
The InfantRisk Center
Contamination effects of organochlorine pesticides on infants
When a mother is exposed to organochlorine pesticides (OCP's), her infant can be exposed to these OCP's through breast milk intake. This result is supported by a study done in India, which revealed that in each lactation period there is a loss of OCPs from the mother's body involved in the nursing of their children. A longitudinal study was conducted to assess pesticide residues in human breast milk samples and evaluate the risk-exposure of infants to these pesticides from consumption of mother’s milk in Ethiopia. The estimated daily intake (EDI) of infants in the present study was above provisional tolerable daily intake (PTDI) during the first month of breastfeeding which indicates that there is a health risk for infants consuming breast milk at an early stage of breastfeeding in the study areas. Based on these studies, the exposure of women during pregnancy to these OCPs may lead to various health problems for fetus such as low birth weight, disturbance of thyroid hormone, and neurodevelopmental delay.
See also
*Breastmilk storage and handling
*Blocked milk duct
*Breastfeeding in public
*Breast milk jewelry
*Human milk banking in North America
*La Leche League International
*Lactation room
*Lactivism
*Mary Rose Tully
References
Further reading
*
External links
Drug Interactions with Human Milk
*
Human milk and lactation
' by Carol L. Wagner (Overview article, eMedicine, December 14, 2010)
– including comparison of human and cow's milk ones
Children's Health Topics: Breastfeeding
A comparison between human milk and cow's milk
an
The composition of cow's milk
* Meigs, EB (August 30, 1913
The comparative composition of human milk and of cow's milk
J.Biol.Chem 147–168
{{Authority control
Breast milk,
Breast
Breastfeeding
Body fluids
Neonatology
Midwifery
Milk by animal
Immunology
Babycare