Human breast milk: A review on its composition and bioactivity
Nicholas J. Andreas1, Beate Kampmann1 3, Kirsty Mehring Le-Doare1 2 3
1
Centre for International Child Health, Department of Paediatrics, Imperial College London, St.
Mary’s Hospital, Praed Street, London, W2 1NY, UK
2
Wellcome Trust Centre for Global Health Research, Norfolk Place, London, UK
3
MRC Unit-The Gambia, Vaccines & Immunity Theme, Atlantic Road, Fajara, The Gambia
n.andreas11@imperial.ac.uk
b.kampmann@imperial.ac.uk
k.mehring-le-doare@imperial.ac.uk
Corresponding author: Nicholas J. Andreas, Department of Paediatrics, Imperial College London, St.
Mary’s Hospital, Praed Street, London, W2 1NY, UK. Tel.: +44 207594 2063.
Keywords: Human milk, Child Nutrition Science, Neonate, Immunity
Conflicts of interest statement: NJA has received support from Medela and Danone to attend an
educational conference, but declared no other conflicts of interest. KLD has received support from
the Wellcome Trust and Thrasher Research Fund for her work. BK is funded by the MRC and has
received support from other funders, such as the Wellcome Trust, the BMGF and the Thrasher
Foundation.
Abbreviations: Group-B streptococcus, GBS; HMO, human milk oligosaccharides; secretory IgA, SIgA;
toll-like receptor, TLR; Transforming growth factor beta, TGF-β;
Acknowledgements: We acknowledge the support of the Imperial College Biomedical Research
Centre and the Wellcome Trust for our work. Also, we would like to acknowledge Jessica Birt,
Amadou Faal, Asmaa Al-Khalidi, and Mustapha Jaiteh.
Abstract
Breast milk is the perfect nutrition for infants, a result of millions of years of evolution, finely attuning
it to the requirements of the infant. Breast milk contains many complex proteins, lipids and
carbohydrates, the concentrations of which alter dramatically over a single feed, as well as over
lactation, to reflect the infant’s needs.
In addition to providing a source of nutrition for infants, breast milk contains a myriad of biologically
active components. These molecules possess diverse roles, both guiding the development of the
infants immune system and intestinal microbiota.
Orchestrating the development of the microbiota are the human milk oligosaccharides, the synthesis
of which are determined by the maternal genotype. In this review, we discuss the composition of
breast milk and the factors that affect it during the course of the breast feeding.
Understanding of the components of breast milk and their functions will allow for the improvement
of clinical practices, infant feeding and our understanding of immune responses to infection and
vaccination in infants.
Introduction
Breast milk is an extremely complex and highly variable biofluid that has evolved over millennia to
nourish infants and protect them from disease whilst their own immune system matures. The
composition of human breast milk changes in response to many factors, matching the infant’s
requirements according to its age and other characteristics (1, 2). Therefore, the composition of breast
milk is widely believed to be specifically tailored by each mother to precisely reflect the requirements
of her infant (3).
The many antimicrobial and immunomodulatory components of breast milk are suggested to
compensate for the deficiencies in the neonatal immune system, and impair the translocation of
infectious pathogens across the gastrointestinal tract (4). In addition, breastfed infants are also known
to possess a more stable and less diverse intestinal microbiota than formula fed infants, but possess
more than twice the number of bacterial cells (5). This may be partially due to alterations at the level
of the gut mucosa due to bioactive substances in human milk.
Demonstrating the bioactivity of breast milk, a study on shed epithelial cells in the faeces of infants
has shown that gene expression in the neonatal gastrointestinal tract is influenced by breastfeeding,
with differential expression found between formula fed and breast fed infants in genes regulating
intestinal cell proliferation, differentiation and barrier function (6).
Breast milk contains bioactive factors that are capable of inhibiting inflammation, as well as enhancing
specific-antibody production, including the compounds PAF-acetylhydrolase, antioxidants,
interleukins 1, 6, 8, and 10, transforming growth factor (TGF), secretory leukocyte protease inhibitors
(SLPI), and defensin 1 (4). Breast milk also contains factors with the potential to mediate
differentiation and growth of B cells, including high concentrations of intracellular adhesion molecule
1 and vascular adhesion molecule 1; and lower concentrations of soluble S-selectin, L-selectin and
CD14, (4).
Additionally, pattern-recognition receptors, which are crucial factors in the recognition of
microorganisms in the neonatal respiratory tract and gut, are present in breast milk. Factors such as
the Toll-like receptors (TLR-2 and TLR-4) provide efficient microbial recognition, working in synergy
with the co-receptor CD14 and soluble CD14, which are found in high quantities in breast milk (7).
Further regulation by soluble toll-like receptor 2 (sTLR-2) which regulates cell activation via cell surface
TLR2 has also been noted in breast milk but not in infant formula (8). Similarly, an as yet unnamed
80kDA protein identified in breast milk appears to inhibit TLR2-mediated but activates TLR-4 mediated
transcriptional responses in human intestinal epithelial and mononuclear cells (9). Reduced TLR-2
responsiveness at birth has been proposed to facilitate the normal establishment of beneficial
microbiota such as bifidobacteria.
Various studies have examined the influences of maternal characteristics on breast milk composition.
Important factors known to influence breast milk composition–such as the gradual increase in fat
concentrations throughout a feed, have well defined effects. However, other potential influences,
such as the mode of delivery and maternal BMI, have less high quality evidence supporting their role.
The difficulties in accurately assessing the composition of breast milk (e.g. sampling time) hinder
efforts to elucidate the true value of these effects. Furthermore, there is a profound lack of knowledge
regarding how alterations in breast milk composition may subsequently impact infant and later health
outcomes.
Metabonomics, the study of multiple metabolites in biofluids, using techniques including mass
spectrometry and 1H NMR spectroscopy, is capable of measuring components in extremely low
concentrations. This may assist in unravelling the factors influencing breast milk composition, as well
as identifying previously unidentified components and their influence on human health (10, 11).
In this review we discuss the nutritional and non-nutritional components of breast milk and the effect
of breast milk components on infant colonisation with potentially pathogenic bacteria and factors
which are known to influence its composition.
Lipid
Lipids are the largest source of energy in breast milk, contributing 40-55% of the total energy of breast
milk (12). These lipids are present as an emulsion. The vast majority of lipids secreted are
triacylglycerides, contributing towards 98% of the lipid fraction. The remainder predominantly
consists of diacylglycerides, monoacylglycerides, free fatty acids, phospholipids and cholesterol. These
components are packaged into milk fat lipid globules, with the phospholipids forming the bulk of the
membrane of the globules and the triacylglycerols found in the core (13), Figure 1. These globules
usually range from 1-10 µm across, with an average diameter in mature milk of 4µm (14).
Figure 1: An optical microscopy image of milk fat lipid globules, displaying the structure of milk.
Adapted with permission from (15), American Chemical Society.
Breast milk contains over 200 fatty acids; however, many of these are present in very low
concentrations, with others dominating, for example oleic acid accounts for 30-40g/100g fat in breast
milk (16). De novo synthesis of fatty acids accounts for approximately 17% of the total fat in breast
milk (17). Long chain polyunsaturated fatty acids, molecules with a chain length of more than 20
carbon atoms-plus 2 or more double bonds, constitute ~2% of the total fatty acids present in breast
milk (18).
The positions occupied by fatty acids along the glycerol backbone are highly conserved, with the fatty
acids commonly appearing in specific positions, Figure 2 (19). For example, fatty acids present in the
highest concentrations in breast milk; oleic, palmitic and linoleic acid, are commonly found at the sn1, sn-2 and sn-3 position respectively (19). Interestingly, the distribution of fatty acids along glycerol
influences their availability; with palmitic acid at the sn-2 position being absorbed more readily.
Significantly, this positional preference is not replicated by many artificial formulas, and has been
observed to influence the infants plasma lipid profile, including cholesterol concentration (20).
Glycerol
sn-1 position
Fatty acids
R
1
sn-2 position
R
2
sn-3 position
R
3
Figure 2: Structure of triacylglycerol with the sn positions annotated.
Adapted with permission
from (21).
Short chain fatty acids (SCFA) found in breast milk are also an important source of energy (22), as well
as being essential for normal maturation of the gastrointestinal tract (23). Sphingomyelins, present in
the milk fat globule membrane, are especially important for central nervous system myelinisation, and
have been shown to improve the neurobehavioral development of low-birth-weight infants (24).
Breast milk lipids have been shown to inactivate a number of pathogens in vitro, including Group-B
streptococcus (GBS). This suggests that lipids provide additional protection from invasive infections at
the mucosal surface, particularly medium chain monoglycerides (25).
Breast milk protein
Breast milk contains over 400 different proteins which perform a variety of functions; providing
nutrition, possessing antimicrobial and immunomodulatory activities, as well as stimulating the
absorption of nutrients (26, 27). Proteins present in milk can be divided into three groups, caseins,
whey and mucin proteins (28). Whey and casein are classified according to their solubility, with the
soluble whey proteins present in solution, whilst caseins are present in casein micelles, suspended in
solution (29). Mucins are present in the milk fat globule membrane (27). Proteins present in significant
quantities in the whey fraction are α-lactalbumin, lactoferrin, IgS, serum albumin and lysozyme (27).
Three types of casein are present in human milk α-, β- and κ-casein. κ-casein stabilises the insoluble
ɑ- and β-caseins forming a colloidal suspension, the casein micelle shown in Figure 3. Caseins do not
form disulfide bonds causing the micelles to form a tangled web structure (30). The total protein
content of human breast milk consists of ~13% casein, the lowest casein concentration of any studied
species, corresponding to the slow growth rate of human infants (31).
Figure 3: Structure of a casein micelle of bovine origin, image from a scanning electron microscope.
Reprinted with permission from Elsevier, International Dairy Journal, Volume 14, Issue 12, Dalgleish
et al., 2004.
Lactocytes produce approximately 80-90% of breast milk protein. The majority of the breast milk
proteins not synthesised by lactocytes are taken up from the maternal circulation via transcytosis,
passing into the lumen (32).
Non-protein nitrogen
Non-protein nitrogen, consisting of molecules such as urea, creatinine, nucleotides, free amino acids
and peptides, contribute towards ~25% of the total nitrogen present in milk (33). This understudied
fraction of breast milk contains many bioactive molecules. For example, nucleotides are considered
as conditionally essential nutrients during early life, and perform key roles in various cell processes,
such as altering enzymatic activities, and acting as metabolic mediators (34). Furthermore, nucleotides
are known to be beneficial for the development, maturation and repair of the gastrointestinal tract
(34), as well as the development of the microbiota (35), and immune function (36).
Antibody in breast milk
Immunoglobulins, present in particularly high concentrations early in lactation, are found in breast
milk as secretory IgA (SIgA), the most predominant form, followed by SIgG. These provide
immunological protection to the infant, whilst its own immune system matures (37). The decrease in
antibody reflects the infants’ decreased requirement as their immune system becomes more
functional. Also, this reflects the increasing inability of the infant gut to absorb whole proteins, as gut
permeability to macromolecules decreases over the first few days of life (38).
Protection from invasive pathogens at the mucosal surface relies heavily on breast milk antibodies, as
neonatal secretions only contain trace amounts of SIgA and SIgM (39). In concordance with this, IgA is
found in breast fed infants faeces on the second day of life, compared to 30% of formula-fed infants
(formula does not contain IgA), whose faeces only contains IgA at one month post-partum (40). The
antibodies found in breast milk occur as a result of antigenic stimulation of maternal mucosaassociated lymphoid tissue (MALT) and bronchial tree (bronchomammary pathway) (41). Therefore,
these antibodies target the infectious agents encountered by the mother during the perinatal period,
meaning they also target the infectious agents most likely to be encountered by the infant. For
example, maternal immunization with a Neisseria meningococcal vaccine demonstrated elevated N.
meningitidis-specific IgA antibodies in breast milk, up to six months post-partum (42).
SIgA is hypothesised to function as the primary protective agent of breast milk (43, 44). In colostrum
SIgA concentrations are around 12 mg/ml whilst mature milk contains only ~1 mg/ml, highlighting the
protective role of colostrum. Breastfed infants ingest approximately 0.5-1.0 g of SIgA per day (45).
SIgA protects against mucosal pathogens via a number of mechanisms, both immobilizing pathogens,
and thereby preventing adherence to epithelial cell surfaces, as well as neutralizing toxins and
virulence factors. SIgA antibodies against bacterial adhesion sites like pili are also found in breast milk
(4, 46). As SIgA is relatively resistant to proteolysis, it is able to provide protection against pathogens
in the gastrointestinal tract (4).
Breast milk contains SIgA antibodies specific for many different enteric and respiratory pathogens. For
example, breast milk contains antibodies protective against Vibrio cholerae, Campylobacter, Shigella,
Giardia lamblia and respiratory tract infections (47-49). SIgA antibodies against bacterial adhesion
sites like pili have been found in breast milk (4, 46). For example, adherence of S. pneumoniae and
Haemophilus influenza to human retropharyngeal cells is blocked by SIgA antibody in breast milk (46).
Group B Streptococcal antibody in breast milk
Several antibody classes present in breast milk appear to protect against neonatal GBS infection (50).
The administration of GBS specific IgM antibodies via breast milk have been shown to protect against
GBS infection in animal models (51). A similar ability to protect against GBS may be obtained from
breast milk SIgA, however, SIgA does not appear to be taken up into the neonatal circulation, (52)
except in preterm infants (53), suggesting SIgAs effectiveness is limited to the mucosal surfaces of the
gastrointestinal tract in term infants.
However, even if SIgA does not cross into neonatal circulation, these antibodies may still afford
protection to neonates, via other mechanisms. SIgA may interfere with the carbohydrate-mediated
attachment of GBS to nasopharyngeal epithelial cells, reducing the colonizing organism load, and
therefore reducing the morbidity and mortality caused by GBS (54).
IgA antibodies to capsular polysaccharide (CPS) type III GBS have been detected in 63% of a cohort of
70 Swedish mothers (55), whilst IgG antibody concentrations to type Ia, II or III have been found in
concentrations approximately 10% of those found in maternal serum (54). To date, no human studies
have demonstrated a correlation between GBS-antibody levels in breast milk and infant colonization.
However, using a rodent model, maternal immunization with GBS CPS-II and CPS-III antibody was
shown to increase pup survival when pups were exposed to breast milk containing high titers of
antibody in comparison to low titers (51, 56).
Carbohydrate
A huge variety of different and complex carbohydrates are present in milk with lactose, a disaccharide
consisting of glucose covalently bound to galactose, being the most abundant by far. Indeed, lactose
is present in the highest concentration in humans compared to any other species, corresponding to
the high energy demands of the human brain. Human milk oligosaccharides (HMO) also make up a
significant fraction of breast milk carbohydrate, but are indigestible by the infant, their function
instead is to nourish the gastrointestinal microbiota (57).
Human Milk Oligosaccharides
Human milk oligosaccharides (HMO) are an important component of human milk carbohydrate, and
are the third largest component in breast milk, totalling on average 12.9g/L in mature milk and 20.9g/L
at 4 days post-partum (57). HMO contain between 3 to 22 saccharide units per molecule, and are
made up of 5 different sugars, found in varying different sequences and orientations. The
monosaccharides which make up the oligosaccharides are L-fucose, D-glucose, D-galactose, Nacetylglucosamine and N-acetylneuraminic acid. There are known to be over 200 different types of
oligosaccharide in human milk, all of which feature lactose at the reducing end (58).
HMO function as prebiotics, encouraging the growth of certain strains of beneficial bacteria, such as
bifidobacterium infantis, within the infant gastrointestinal tract, protecting the infant from
colonisation by pathogenic bacteria (59). HMO play an important role in preventing neonatal
diarrhoeal and respiratory tract infections (60, 61).
The production of HMO is genetically determined, different profiles of milk oligosaccharide occur as a
result of specific transferase enzymes expressed in the lactocytes. Two such genes, important for
determining the HMO profile a mother produces, are the Secretor, and Lewis blood group genes. The
Secretor gene encodes for the enzyme α(1,2)-fucosyltransferase (FUT2), responsible for linking fucose
in a α1-2 linkage to elongate the HMO chain. The enzyme FUT3 is encoded for by the Lewis blood
group gene; this enzyme catalyses the reaction between fucose in a α1-3/4 linkage, creating further
fucosylated oligosaccharides, Figure 4. As a result of the different expressions of these enzymes, there
are four main phenotypes in relation to HMO profile; Se+/Le+, Se-/Le+, Se+/Le- and Se-/Le- (62).
Furthermore, HMO have been observed to modulate intestinal epithelial cell responses, as well as
acting as immune modulators, altering both the environment of the intestine, by reducing cell growth,
and inducing differentiation and apoptosis (63), as well as immune responses, potentially shifting Tcell responses to a balanced Th1/Th2-cytokine production (64).
One study investigating breast milk HMO profile demonstrated Se+/Le+ mothers produced all types of
fucosylated oligosaccharides, whilst Se-/Le+ mothers did not produce α1,2-fucosylated structures,
such as 2’-fucosyllactose. Se+/Le- mothers secreted α1,2- and α1,3-fucosylated oligosaccharides, but
not HMO containing α1,4-fucose residues (65). However, it was noted that in Se-/Le+ mothers, α1,3fucosylated oligosaccharides, such as 3’-fucosyllactose, were between two to fivefold higher than in
Se+/Le+ mother’s breast milk. This suggests there is an increase in FucT3 activity in non-secretor
mothers, meaning that the total oligosaccharide production is relatively equal between the different
groups (65).
One mechanism by which HMO protect infants against gastrointestinal infection is by acting as
receptor decoys. A crucial step in the initiation of infection is the binding of pathogens to
carbohydrates present on intestinal epithelial cells. HMO inhibit this process due to their analogous
shapes to cell surface carbohydrates: pathogens recognise and bind to HMOs anchoring the bacteria
in the mucosal layer and prevent cell adhesion to epithelial cells. Once bound, pathogens pass
harmlessly from the gastrointestinal tract. An observational study found a significant association
between levels of specific 2-linked fucosylated oligosaccharides in human milk and rates of
Campylobacter diarrhoea infection in breast fed infants. Furthermore, infants who received milk
containing a low concentration of lacto-N-difucohexaose had an increased incidence of calicivirus
diarrhoea (66). HMO also prevent the adherence of S. pneumonia (67) and Escherichia coli (68),
suggesting HMO are capable of delivering protection against many bacterial and viral infections. GBS
type Ib and II polysaccharides are virtually identical to certain HMO present in breast milk (56, 69, 70)
raising the possibility of cross-reactivity with HMO (71).
Different pathogen receptors have different affinities for specific carbohydrate structures, as the
structures of the HMO produced are genetically determined: mothers possessing different genotypes,
and therefore different HMO profiles, may protect their infants against certain infections to a greater
or lesser extent, depending on the presence of specific HMOs. Likewise, the different HMO produced
alters the types of microbiota colonising infants, as well as the timing of the establishment of the
microbiota (72).
Figure 4: Structure of 2’- and 3’-fucosyllactose. Reproduced from (73).
Influences on breast milk composition
Breast milk composition is extremely complex, varying with the time of day, stage of the nursing
process, and many other factors, with the lipid being most variable in terms of concentration (74).
Time associated changes in breast milk composition
Length of Lactation
Milk is commonly classified into colostrum, transitional milk and mature milk, however, these are not
distinct classes of milk, but refer to the gradual alteration in the content of milk throughout lactation
(33). Colostrum, the first milk produced, is significantly different from mature milk, containing high
concentrations of whey protein, whilst the caseins are almost undetectable (27). The average content
of protein in breast milk gradually decreases from the second month to the seventh month, after
which the speed of reduction of protein content levels off. Colostrum contains low concentrations of
both lactose and fat in comparison to mature milk (33, 75). Lactose production is highest in the forth
to seventh month, after which it decreases, whilst a gradual increase in the concentration of lipid
occurs over lactation (76).
Colostrum is dramatically different to mature breast milk in terms of its bioactive properties,
containing high concentrations of secretory immunoglobulin (77). These qualities suggest that the
primary role of colostrum is not nutritional, but immunologic, protecting the baby as it emerges from
the relatively sterile environment of the womb, to being exposed to many environmental pathogens.
In agreement with this, the concentration of HMO in colostrum is particularly high, being
approximately double that of mature milk, with concentrations reducing from ~21 g/L to ~13 g/L from
day 4 to day 120 post-partum (78).
As well as its immunologic and nutritional roles, colostrum appears to also act as a growth promoter.
Colostrum contains many growth factors, again often in greater concentrations than in mature milk,
for example, epidermal growth factor (79), TGF-β (80) and colony stimulating factor-1 (81) are all
found in higher concentrations in colostrum than mature breast milk.
Time since last feed
One of the most significant predictors of milk fat concentration is the length of time since the last
feed; the longer this interval is, the lower the concentration of fat in the milk. In keeping with this, fat
concentrations at the end of the previous feed, as well as the volume of milk received at the previous
feed, have been found to be particularly important predictors of milk fat concentration (82).
Stage of the nursing process
The stage of the nursing process results in a large alteration in the composition of breast milk,
responsible for some of the largest variabilities seen in milk composition. There is a gradual increase
in the fat content from the beginning, known as fore milk, to the end of a feed, hind milk, whilst lactose
shows an inverse correlation to the change in fat content (83).
Diurnal variation
A diurnal variation in milk fat concentration occurs, with a peak fat content occurring at midmorning,
and a low overnight, varying from ~5g/100ml to ~3g/100ml (33).
Maternal characteristics altering breast milk composition
Age of Mother
Protein concentration is highest in breast milk of mothers aged 20-30, however, maternal age does
not seem to influence either lipid or lactose concentrations (76), and maternal age does not have a
large impact on breast milk composition.
Diet
The influence of maternal diet on breast milk composition is complex. Depending on the type of
nutrient, maternal diet can have virtually no impact on a nutrients concentration, whilst for other
nutrients, maternal diet can result in large variations (84).
Previous research on the macronutrient content of breast milk from mothers of different ethnicities
found little variation based on diet (85), and the variation in milk lipid concentration appears to be
independent of maternal diet (86). However, the specific fatty acids which form the lipid fraction are
sensitive to maternal diet. These fatty acids are either endogenously synthesised by the mammary
gland, or taken up from the maternal plasma, and both of these fatty acid sources are influenced by
maternal diet (87).
Numerous studies investigating the fatty acid profile of breast milk have noted that it can be altered
by manipulating the maternal diet (87-89), especially the monounsaturated omega-6 and omega–3
fatty acids. Dietary fatty acids are transferred rapidly to breast milk, and within 2 to 3 days breast milk
changes to mimic that of dietary fat (90).
The mammary gland is capable of synthesizing the medium-chain fatty acids (MCFAs) 10:0, 12:0 and
14:0. Women receiving a high carbohydrate, low fat diet have been observed to increase MCFA
synthesis in order to maintain the quantity of triacylglycerides in breast milk (91).
Ethnicity
An analysis summarising research on the composition of milk of mothers from seven countries
suggests breast milk composition is relatively consistent across different ethnicities. Of the variation
which was observed, fat content was seen to vary by the greatest amount. Importantly, the magnitude
of inter-individual variation between mothers of the same ethnicity was as great as that observed
between mothers of different ethnicities (33).
Weight gain during pregnancy
A correlation between maternal weight gain during pregnancy and breast milk fat content has been
reported, however, this was only observed to be significant at four months post-partum. The authors
hypothesise that this phenomenon may be due to the laying down of fat stores during pregnancy,
which are used as an energy reserve during lactation and subsequently more quickly diminished in the
low weight gain group of mothers (92). Despite this finding, two further studies were unable to identify
an association between maternal weight gain during pregnancy and breast milk fat content (93), (94).
Birth weight
Milk fat concentration increases when a deviation from normal birth weight occurs; i.e. there is a ushaped association between fat content and infant birth weight, with a 20-30% increase observed at
the lowest and highest infant birth weights. Protein and carbohydrate concentration do not appear to
change significantly in relation to infant birth weight (2). However, this study did not collect
information on length of gestation; therefore, this influence may simply be a marker of the maturity
of the infant.
Summary
Studying the composition of breast milk can be challenging, in such a dynamic fluid without a
benchmark against which to compare. However, if we are to improve the understanding of the biology
of the lactating mother and her infant, as well as improving the quality of formula milks produced,
investigating this is a necessity. Also, exactly how the composition of breast milk alters, and the
downstream effects this may have on subsequent adult health will be of great interest in regard to
the programming of the human metabolism during this early period.
Many unknowns remain. Although some preliminary data exists, exactly how different profiles of HMO
influence the species and types of bacteria which colonise the infants gastrointestinal tract, and how
these microbiota subsequently influence the biology of the host are all questions of great interest.
Likewise, just how infant genotype influences the environment of the intestine, and how this
influences the species of microbiota present is yet to be delineated. Furthermore, many components
of breast milk alter during digestion, taking on new properties, and the consequences of this for infant
immunity from infection and infant growth have not been sufficiently examined.
Breast milk is vital in protecting infants from neonatal sepsis and for the promotion of infant growth
and development. Its role in the mediation of potentially pathogenic gut organisms is just emerging
and components such as HMO may prove useful adjuncts to antimicrobial therapy.
References
1.
Fujita M, Roth E, Lo YJ, Hurst C, Vollner J, Kendell A. In poor families, mothers' milk is richer
for daughters than sons: a test of Trivers-Willard hypothesis in agropastoral settlements in Northern
Kenya. American journal of physical anthropology. 2012;149(1):52-9.
2.
Michaelsen KF, Skafte L, Badsberg JH, Jorgensen M. Variation in macronutrients in human
bank milk: influencing factors and implications for human milk banking. J Pediatr Gastroenterol Nutr.
1990;11(2):229-39.
3.
The Surgeon General's Call to Action to Support Breastfeeding. Publications and Reports of
the Surgeon General. Rockville (MD)2011.
4.
Hanson LA, Korotkova M. The role of breastfeeding in prevention of neonatal infection.
Semin Neonatol. 2002;7(4):275-81.
5.
Bezirtzoglou E, Tsiotsias A, Welling GW. Microbiota profile in feces of breast- and formulafed newborns by using fluorescence in situ hybridization (FISH). Anaerobe. 2011;17(6):478-82.
6.
Donovan SM, Wang M, Monaco MH, Martin CR, Davidson LA, Ivanov I, et al. Noninvasive
molecular fingerprinting of host-microbiome interactions in neonates. FEBS Lett. 2014;588(22):41129.
7.
Labeta MO, Vidal K, Nores JE, Arias M, Vita N, Morgan BP, et al. Innate recognition of
bacteria in human milk is mediated by a milk-derived highly expressed pattern recognition receptor,
soluble CD14. J Exp Med. 2000;191(10):1807-12.
8.
Levy O. Innate immunity of the newborn: basic mechanisms and clinical correlates. Nat Rev
Immunol. 2007;7(5):379-90.
9.
LeBouder E, Rey-Nores JE, Raby AC, Affolter M, Vidal K, Thornton CA, et al. Modulation of
neonatal microbial recognition: TLR-mediated innate immune responses are specifically and
differentially modulated by human milk. J Immunol. 2006;176(6):3742-52.
10.
Andreas NJ, Hyde MJ, Gomez-Romero M, Lopez-Gonzalvez MA, Villasenor A, Wijeyesekera A,
et al. Multiplatform characterization of dynamic changes in breast milk during lactation.
Electrophoresis. 2015.
11.
Villasenor A, Garcia-Perez I, Garcia A, Posma JM, Fernandez-Lopez M, Nicholas AJ, et al.
Breast milk metabolome characterization in a single-phase extraction, multiplatform analytical
approach. Anal Chem. 2014;86(16):8245-52.
12.
Koletzko B, Rodriguez-Palmero M, Demmelmair H, Fidler N, Jensen R, Sauerwald T.
Physiological aspects of human milk lipids. Early human development. 2001;65 Suppl:S3-S18.
13.
Lopez C, Menard O. Human milk fat globules: polar lipid composition and in situ structural
investigations revealing the heterogeneous distribution of proteins and the lateral segregation of
sphingomyelin in the biological membrane. Colloids and surfaces B, Biointerfaces. 2011;83(1):29-41.
14.
Michalski MC, Briard V, Michel F, Tasson F, Poulain P. Size distribution of fat globules in
human colostrum, breast milk, and infant formula. Journal of dairy science. 2005;88(6):1927-40.
15.
Zou XQ, Guo Z, Huang JH, Jin QZ, Cheong LZ, Wang XG, et al. Human milk fat globules from
different stages of lactation: a lipid composition analysis and microstructure characterization. J Agric
Food Chem. 2012;60(29):7158-67.
16.
Koletzko B, Mrotzek M, Bremer HJ. Fatty acid composition of mature human milk in
Germany. Am J Clin Nutr. 1988;47(6):954-9.
17.
Prentice A, Jarjou LM, Drury PJ, Dewit O, Crawford MA. Breast-milk fatty acids of rural
Gambian mothers: effects of diet and maternal parity. J Pediatr Gastroenterol Nutr. 1989;8(4):48690.
18.
Laryea MD, Leichsenring M, Mrotzek M, el-Amin EO, el Kharib AO, Ahmed HM, et al. Fatty
acid composition of the milk of well-nourished Sudanese women. Int J Food Sci Nutr.
1995;46(3):205-14.
19.
Martin JC, Bougnoux P, Antoine JM, Lanson M, Couet C. Triacylglycerol structure of human
colostrum and mature milk. Lipids. 1993;28(7):637-43.
20.
Innis SM, Quinlan P, Diersen-Schade D. Saturated fatty acid chain length and positional
distribution in infant formula: effects on growth and plasma lipids and ketones in piglets. Am J Clin
Nutr. 1993;57(3):382-90.
21.
Alvarez HM, Steinbuchel A. Triacylglycerols in prokaryotic microorganisms. Appl Microbiol
Biot. 2002;60(4):367-76.
22.
Donohoe DR, Garge N, Zhang X, Sun W, O'Connell TM, Bunger MK, et al. The microbiome
and butyrate regulate energy metabolism and autophagy in the mammalian colon. Cell metabolism.
2011;13(5):517-26.
23.
Peng L, Li ZR, Green RS, Holzman IR, Lin J. Butyrate enhances the intestinal barrier by
facilitating tight junction assembly via activation of AMP-activated protein kinase in Caco-2 cell
monolayers. J Nutr. 2009;139(9):1619-25.
24.
Tanaka K, Hosozawa M, Kudo N, Yoshikawa N, Hisata K, Shoji H, et al. The pilot study:
Sphingomyelin-fortified milk has a positive association with the neurobehavioural development of
very low birth weight infants during infancy, randomized control trial. Brain Dev-Jpn. 2013;35(1):4552.
25.
Isaacs CE, Litov RE, Thormar H. Antimicrobial activity of lipids added to human milk, infant
formula, and bovine milk. J Nutr Biochem. 1995;6(7):362-6.
26.
Molinari CE, Casadio YS, Hartmann BT, Livk A, Bringans S, Arthur PG, et al. Proteome
mapping of human skim milk proteins in term and preterm milk. J Proteome Res. 2012;11(3):1696714.
27.
Lonnerdal B. Human milk proteins: key components for the biological activity of human milk.
Adv Exp Med Biol. 2004;554:11-25.
28.
Lonnerdal B. Nutritional and physiologic significance of human milk proteins. Am J Clin Nutr.
2003;77(6):1537S-43S.
29.
Jensen R. Handbook of Milk Composition. San Diego: Academic Press, Inc.; 1995.
30.
Holt C, Horne DS. The hairy casein micelle: Evolution of the concept and its implications for
dairy technology. Neth Milk Dairy J. 1996;50(2):85-111.
31.
Lonnerdal B, Woodhouse LR, Glazier C. Compartmentalization and quantitation of protein in
human milk. J Nutr. 1987;117(8):1385-95.
32.
Neville M AJWC. Lactation: Physiology, Nutrition and Breastfeeding. New York: Plenum
Press; 1983.
33.
Jenness R. The composition of human milk. Semin Perinatol. 1979;3(3):225-39.
34.
Uauy R, Quan R, Gil A. Role of nucleotides in intestinal development and repair: implications
for infant nutrition. J Nutr. 1994;124(8 Suppl):1436S-41S.
35.
Singhal A, Macfarlane G, Macfarlane S, Lanigan J, Kennedy K, Elias-Jones A, et al. Dietary
nucleotides and fecal microbiota in formula-fed infants: a randomized controlled trial. Am J Clin
Nutr. 2008;87(6):1785-92.
36.
Gutierrez-Castrellon P, Mora-Magana I, Diaz-Garcia L, Jimenez-Gutierrez C, Ramirez-Mayans
J, Solomon-Santibanez GA. Immune response to nucleotide-supplemented infant formulae:
systematic review and meta-analysis. Br J Nutr. 2007;98 Suppl 1:S64-7.
37.
Hurley WL, Theil PK. Perspectives on immunoglobulins in colostrum and milk. Nutrients.
2011;3(4):442-74.
38.
Vukavic T. Timing of the gut closure. J Pediatr Gastroenterol Nutr. 1984;3(5):700-3.
39.
Brandtzaeg P. Induction of secretory immunity and memory at mucosal surfaces. Vaccine.
2007;25(30):5467-84.
40.
Jatsyk GV, Kuvaeva IB, Gribakin SG. Immunological protection of the neonatal
gastrointestinal tract: the importance of breast feeding. Acta Paediatr Scand. 1985;74(2):246-9.
41.
Goldman AS. Modulation of the gastrointestinal tract of infants by human milk. Interfaces
and interactions. An evolutionary perspective. The Journal of nutrition. 2000;130(2S Suppl):426S31S.
42.
Shahid NS, Steinhoff MC, Roy E, Begum T, Thompson CM, Siber GR. Placental and breast
transfer of antibodies after maternal immunization with polysaccharide meningococcal vaccine: a
randomized, controlled evaluation. Vaccine. 2002;20(17-18):2404-9.
43.
Krakauer R, Zinneman HH, Hong R. Deficiency of secretory Ig-A and intestinal malabsorption.
Am J Gastroenterol. 1975;64(4):319-23.
44.
Dickinson EC, Gorga JC, Garrett M, Tuncer R, Boyle P, Watkins SC, et al. Immunoglobulin A
supplementation abrogates bacterial translocation and preserves the architecture of the intestinal
epithelium. Surgery. 1998;124(2):284-90.
45.
Lawrence RM, Lawrence RA. Breast milk and infection. Clin Perinatol. 2004;31(3):501-28.
46.
Svanborg Eden C CB, Hanson LÅ, et al. . Anti-piliantibodies in breast milk. Lancet 1979.
Lancet. 1979;ii:1235.
47.
Walterspiel JN, Morrow AL, Guerrero ML, Ruiz-Palacios GM, Pickering LK. Secretory antiGiardia lamblia antibodies in human milk: protective effect against diarrhea. Pediatrics.
1994;93(1):28-31.
48.
Edmond K, Zaidi A. New approaches to preventing, diagnosing, and treating neonatal sepsis.
PLoS Med. 2010;7(3):e1000213.
49.
Cruz JR, Gil L, Cano F, Caceres P, Pareja G. Breast milk anti-Escherichia coli heat-labile toxin
IgA antibodies protect against toxin-induced infantile diarrhea. Acta Paediatr Scand. 1988;77(5):65862.
50.
Le Doare K, Kampmann B. Breast milk and Group B streptococcal infection: Vector of
transmission or vehicle for protection? Vaccine. 2014;32(26):3128-32.
51.
Heiman HS WL. Transplacental or enteral transfer of maternal immunization-induced
antibody protects suckling rats from type III group B streptococcal infection. Pediatr Res
1989;26(6):629-32.
52.
Stephens S, Kennedy CR, Lakhani PK, Brenner MK. In-vivo immune responses of breast- and
bottle-fed infants to tetanus toxoid antigen and to normal gut flora. Acta Paediatr Scand.
1984;73(4):426-32.
53.
Weaver LT WN, Taylor CE, Greenwell J, Toms GL. . The ontogeny of serum IgA in the
newborn. . Pediatr Allergy Immunol 1991;2:2-75.
54.
Weisman LE, Dobson FM. The potential impact of group B streptococcal antibodies in breast
milk. Adv Exp Med Biol. 1991;310:345-51.
55.
Lagergard T, Thiringer K, Wassen L, Schneerson R, Trollfors B. Isotype composition of
antibodies to streptococcus group B type III polysaccharide and to tetanus toxoid in maternal, cord
blood sera and in breast milk. Eur J Pediatr. 1992;151(2):98-102.
56.
Gray BM, Egan ML, Pritchard DG. Specificity of monoclonal antibodies against group B
streptococcus type II and inhibition of their binding by human secretions. Pediatr Res. 1988;24(1):6872.
57.
Coppa GV, Gabrielli O, Pierani P, Catassi C, Carlucci A, Giorgi PL. Changes in carbohydrate
composition in human milk over 4 months of lactation. Pediatrics. 1993;91(3):637-41.
58.
German JB, Freeman SL, Lebrilla CB, Mills DA. Human milk oligosaccharides: evolution,
structures and bioselectivity as substrates for intestinal bacteria. Nestle Nutrition workshop series
Paediatric programme. 2008;62:205-18; discussion 18-22.
59.
Ward RE, Ninonuevo M, Mills DA, Lebrilla CB, German JB. In vitro fermentation of breast milk
oligosaccharides by Bifidobacterium infantis and Lactobacillus gasseri. Applied and environmental
microbiology. 2006;72(6):4497-9.
60.
Newburg DS, Walker WA. Protection of the neonate by the innate immune system of
developing gut and of human milk. Pediatr Res. 2007;61(1):2-8.
61.
Morrow AL, Ruiz-Palacios GM, Altaye M, Jiang X, Guerrero ML, Meinzen-Derr JK, et al.
Human milk oligosaccharide blood group epitopes and innate immune protection against
campylobacter and calicivirus diarrhea in breastfed infants. Adv Exp Med Biol. 2004;554:443-6.
62.
Thurl S, Henker J, Siegel M, Tovar K, Sawatzki G. Detection of four human milk groups with
respect to Lewis blood group dependent oligosaccharides. Glycoconj J. 1997;14(7):795-9.
63.
Kuntz S, Kunz C, Rudloff S. Oligosaccharides from human milk induce growth arrest via G2/M
by influencing growth-related cell cycle genes in intestinal epithelial cells. Br J Nutr.
2009;101(9):1306-15.
64.
Eiwegger T, Stahl B, Haidl P, Schmitt J, Boehm G, Dehlink E, et al. Prebiotic oligosaccharides:
in vitro evidence for gastrointestinal epithelial transfer and immunomodulatory properties. Pediatr
Allergy Immunol. 2010;21(8):1179-88.
65.
Pratico G, Capuani G, Tomassini A, Baldassarre ME, Delfini M, Miccheli A. Exploring human
breast milk composition by NMR-based metabolomics. Nat Prod Res. 2013.
66.
Morrow AL, Ruiz-Palacios GM, Altaye M, Jiang X, Guerrero ML, Meinzen-Derr JK, et al.
Human milk oligosaccharides are associated with protection against diarrhea in breast-fed infants. J
Pediatr. 2004;145(3):297-303.
67.
Andersson B, Porras O, Hanson LA, Lagergard T, Svanborg-Eden C. Inhibition of attachment
of Streptococcus pneumoniae and Haemophilus influenzae by human milk and receptor
oligosaccharides. J Infect Dis. 1986;153(2):232-7.
68.
Cravioto A, Tello A, Villafan H, Ruiz J, del Vedovo S, Neeser JR. Inhibition of localized
adhesion of enteropathogenic Escherichia coli to HEp-2 cells by immunoglobulin and oligosaccharide
fractions of human colostrum and breast milk. J Infect Dis. 1991;163(6):1247-55.
69.
Wilkinson HW. Immunochemistry of purified polysaccharide type antigens of group B
streptococcal types Ia, Ib, and Ic. Infect Immun. 1975;11(4):845-52.
70.
Kobata A. Structures and application of oligosaccharides in human milk. Proc Jpn Acad Ser B
Phys Biol Sci. 2010;86(7):731-47.
71.
Pritchard DG, Gray BM, Egan ML. Murine monoclonal antibodies to type Ib polysaccharide of
group B streptococci bind to human milk oligosaccharides. Infect Immun. 1992;60(4):1598-602.
72.
Lewis ZT, Totten SM, Smilowitz JT, Popovic M, Parker E, Lemay DG, et al. Maternal
fucosyltransferase 2 status affects the gut bifidobacterial communities of breastfed infants.
Microbiome. 2015;3:13.
73.
Pereira CL, McDonald FE. Synthesis of Human Milk Oligosaccharides: 2 '- and 3 'Fucosyllactose. Heterocycles. 2012;84(1):637-55.
74.
Lawrence RA LR. Breastfeeding A Guide for the Medical Profession. 6 ed2005.
75.
Saint L, Smith M, Hartmann PE. The yield and nutrient content of colostrum and milk of
women from giving birth to 1 month post-partum. Br J Nutr. 1984;52(1):87-95.
76.
Kader MM, Bahgat R, Aziz MT, Hefnawi F, Badraoui MH, Younis N, et al. Lactation patterns in
Egyptian women. II. Chemical composition of milk during the first year of lactation. J Biosoc Sci.
1972;4(4):403-9.
77.
Castellote C, Casillas R, Ramirez-Santana C, Perez-Cano FJ, Castell M, Moretones MG, et al.
Premature delivery influences the immunological composition of colostrum and transitional and
mature human milk. J Nutr. 2011;141(6):1181-7.
78.
Coppa GV, Pierani P, Zampini L, Carloni I, Carlucci A, Gabrielli O. Oligosaccharides in human
milk during different phases of lactation. Acta Paediatr Suppl. 1999;88(430):89-94.
79.
Okada M, Ohmura E, Kamiya Y, Murakami H, Onoda N, Iwashita M, et al. Transforming
growth factor (TGF)-alpha in human milk. Life sciences. 1991;48(12):1151-6.
80.
Saito S, Yoshida M, Ichijo M, Ishizaka S, Tsujii T. Transforming growth factor-beta (TGF-beta)
in human milk. Clinical and experimental immunology. 1993;94(1):220-4.
81.
Flidel-Rimon O, Roth P. Effects of milk-borne colony stimulating factor-1 on circulating
growth factor levels in the newborn infant. J Pediatr. 1997;131(5):748-50.
82.
Jackson DA, Imong SM, Silprasert A, Ruckphaopunt S, Woolridge MW, Baum JD, et al.
Circadian variation in fat concentration of breast-milk in a rural northern Thai population. Br J Nutr.
1988;59(3):349-63.
83.
Hytten FE. Clinical and chemical studies in human lactation. Br Med J. 1954;1(4855):175-82.
84.
Innis SM. Impact of maternal diet on human milk composition and neurological development
of infants. Am J Clin Nutr. 2014;99(3):734S-41S.
85.
Lonnerdal B, Forsum E, Gebre-Medhin M, Hambraeus L. Breast milk composition in Ethiopian
and Swedish mothers. II. Lactose, nitrogen, and protein contents. Am J Clin Nutr. 1976;29(10):113441.
86.
Ballard O, Morrow AL. Human milk composition: nutrients and bioactive factors. Pediatr Clin
North Am. 2013;60(1):49-74.
87.
Innis SM. Human milk and formula fatty acids. J Pediatr. 1992;120(4 Pt 2):S56-61.
88.
Brenna JT, Varamini B, Jensen RG, Diersen-Schade DA, Boettcher JA, Arterburn LM.
Docosahexaenoic and arachidonic acid concentrations in human breast milk worldwide. Am J Clin
Nutr. 2007;85(6):1457-64.
89.
Koletzko B, Thiel I, Abiodun PO. The fatty acid composition of human milk in Europe and
Africa. J Pediatr. 1992;120(4 Pt 2):S62-70.
90.
Insull W, Jr., Hirsch J, James T, Ahrens EH, Jr. The fatty acids of human milk. II. Alterations
produced by manipulation of caloric balance and exchange of dietary fats. The Journal of clinical
investigation. 1959;38(2):443-50.
91.
Novak EM, Innis SM. Impact of maternal dietary n-3 and n-6 fatty acids on milk mediumchain fatty acids and the implications for neonatal liver metabolism. American journal of physiology
Endocrinology and metabolism. 2011;301(5):E807-17.
92.
Michaelsen KF. Nutrition and growth during infancy. The Copenhagen Cohort Study. Acta
Paediatr Suppl. 1997;420:1-36.
93.
Butte NF, Garza C, Stuff JE, Smith EO, Nichols BL. Effect of maternal diet and body
composition on lactational performance. Am J Clin Nutr. 1984;39(2):296-306.
94.
Dewey KG FD, Strode MA, Lonnerdal B. Human lactation II maternal and environmental
factors. New York:: Plenum Press,; 1986.