Just to kick things off, here’s a list of the contents of human breast milk. Which I’ve taken from BreastFeeding Thoughts on Facebook (please like their page if you want to learn more):

Key Molecules Breast Milk Glossary:

Generic terms:

Carbohydrates, in their simplest form they are a molecule containing a carbon, hydrogen and an oxygen. In human biology the carbohydrates that we are interested in are saccharides, which is an umbrella term for any sugar or starch.

Monosaccharides are simple single sugars units and include glucose and fructose. Disaccharides are two monosaccharides bound together and include lactose and sucrose
Oligosaccharides are small multi sugar units (typically 3-9 monosaccharides), they have an important role in cell to cell recognition and other functions. They help to block
antigens from sticking to the wall of the gastrointestinal tract. This blocking mechanism is particularly effective against pneumococcus which is extremely sticky.
Polysaccharides are larger multi sugar units and include starch and glycogen.

Fats are an essential nutrients required by the body for a range of functions. Functions of fats include storage of energy, transport, structural roles (fat soluble molecules such as certain vitamins are stored in fats). The break down of fats releases heat energy, which helps to keep us warm. Fats are also an important producer of hormones.

Amino acids are small organic chemical compounds, which are the individual building blocks for proteins. There are 22 amino acids, which used by humans for proteins synthesis. Essential amino acids are ones which the body cannot produce itself, other than in human milk. There are 9 essential amino acids, all present in human milk.

Proteins are three-dimensional structures comprised of amino acids. Proteins are essential biological molecules with a vast range of functions from cell to cell signalling, transport of other factors around the body (e.g. oxygen) and structural roles. Every protein consists of a specific sequence of amino acids. Every protein has a corresponding gene, which is essentially a set of instructions a cell uses to determine the order of amino acids. The order of amino acids will dictate the 3D shape of the protein and the structure of the protein dictates its function.

Enzymes are a specialised protein, which mediate chemical reactions in the body. A number of processes in the body require chemical reactions to occur, examples include the metabolism of glucose, the detoxification of drugs and harmful substances and the formation of waste products for excretion. Enzymes lower the energy requirements for these reactions to occur.

DNA/Genes: Every cell in the human body has a nucleus. The nucleus contains the all of the genetic material relating to that particular individual. Every cell contains the same genetic material, regardless of the cell type. The genetic material is database of instructions for creating proteins. The genetic material is expressed as chains of molecules called DNA, lots of DNA is random irrelevant ‘junk’ DNA with no real purpose, however, some is useful and these sections are called genes. DNA is converted in cells to RNA, which then instructs proteins within the cell to make new proteins.

COMPONENTS OF HUMAN MILK:

AMINO ACIDS:

Amino acids are the individual building blocks for proteins. Proteins make up approximately 20% of the human body. Breast milk contains the 9 essential amino acids, which the body cannot produce itself other than in breast milk (listed in bold), as well as others, which are critical for development in all areas.

Alanine
Arginine
Aspartate
Clycine
Cystine
Glutamate
Histidine
Isoleucine
Leucine
Lyscine
Methionine
Phenylalanine
Proline
Serine
Taurine. The second most abundant amino acid in human milk. It plays an important role in early brain maturation.
Theronine
Tryptophan
Tyrosine
Valine
Carnitine

NUCLEOTIDES:

Nucleotides are the subunits of nucleic acids such as DNA and RNA. The can also form cyclic structures which can be involved in cell signalling (activating or inhibiting activity in cells).

5’-Adenosine monophosphate (5”-AMP)
3’:5’-Cyclic adenosine monophosphate (3’:5’-cyclic AMP)
5’-Cytidine monophosphate (5’-CMP)

Cytidine diphosphate choline (CDP choline)
Important for the maintenance of cell membrane proteins particularly in the nervous system, some evidence to suggests it has a protective role against hypoxic brain damage, and helping to improve memory and learning.

Guanosine diphosphate (UDP)
Guanosine diphosphate – mannose
Uridine monophosphate (3’-UMP)
Uridine diphosphate (UDP)
Uridine diphosphate hexose (UDPH)
Uridine diphosphate-N-acetylhexosamine (UDPAH)

Uridine diphosphoglucuronic acid (UDPGA)
Important for the production of essential sugars, required for normal growth and development.

FATS/FAT BASED MOLECULES:

Triglycerides and Long-chain polyunsaturated fatty acids are fat based molecules. Fats in general have a number of functions including: energy storage, cell messaging, hormone production and structural roles.

Docosahexaenoic acid (DHA) A fatty acid shown to have an important role in infant brain development, particularly with association and short term memory.

Arachidonic acid (AHA) A fatty acid required for the synthesis of molecules involved in pain and inflammation. Also thought to play a role in infant brain development

Linoleic acid (Omega 6)/ Alpha-linolenic acid (ALA) (Omega 3) An essential fatty acid which is thought to have numerous roles in the body, from possible anti-cancer properties to the reduction of cholesterol levels.

Eicosapentaenoic acid (EPA)
Conjugated linoleic acid (Rumenic acid- active omega 6)
Free Fatty Acids
Oleic acid (possible adverse effects)
Palmitoleic acid
Heptadecenoic acid
Stearic acid
Palmitic acid
Lauric acid

Phosphatidylcholine
Important phospholipid (fat with a phosphate group bound), found in every cell in the body, thought to have a role reducing the risk of inflammatory bowel disease and tissue repair.

Phosphatidylethanolamine

Phosphatidylinositol
A phospholipid essential for cell structure, which is partially prevalent in brain tissue

Lysophosphatidylcholine
A compound derived from phospholipids, thought to have potential anti-cancer properties.

Lysophosphatidylethanolamine
Plasmalogens
Sphingolipids
Sphingomyelin
GM1
GM2
GM3
Glucosylceramide
Galactosylceramide
Lactosylceramide
Globotriaosylceramide (GB3)
Globoside (GB4)
Sterols
Squalene
Lanosterol
Dimethylsterol
Methosterol
Lathosterol
Desmosterol
Triacylglycerol (triglyceride)
Cholesterol
7-dehydrocholesterol
Stigma-and campesterol
7-ketocholesterol
Sitosterol
β-lathosterol

VITAMINS AND MINERALS:

In general vitamins and minerals are used in a variety of roles. Most are essential for growth and development and deficiency can lead to problems. With adequate nutrition it’s unusual to be deficient in these.

Vitamin A
An essential vitamin required for vision and healthy skin.
Beta carotene
Vitamin B6
Vitamin B8 (Inositol)
Vitamin B12
Needed for early development of the central nervous system.
Vitamin C
Vitamin D
Vitamin EImportant for the protection of delicate tissues against oxidant induced injury such as the lungs and retina.
a-Tocopherol
Vitamin K
Thiamine
Riboflavin
Niacin
Folic acid
Pantothenic acid
Biotin
Calcium. Essential mineral and is the most abundant mineral in the body, functions range from heart contractions to development of teeth and bones.
Sodium
Potassium
Iron
ZincShown to be protective against some rare but serious congenital conditions.
Chloride
Phosphorus
Magnesium
Copper
Manganese
Iodine
Selenium
Choline
Sulphur
Chromium
Cobalt
Fluorine
Nickel
Molybdenum (essential element in many enzymes)

GROWTH FACTORS/INFLAMMATORY MEDIATORS:

CytokinesCytokines are involved in the regulation of the immune system. In babies they have an important role in protection from disease.

Stem cells. These are a unique kind of cell which can divide and self-renew to create and repair different organs and systems. Early testing has shown these stem cells may be able to regenerate brain cells and they could have a part to play in early brain development or longer-term protection against conditions like Alzheimers. Stem cells are being used in research for a wide variety of diseases.

Interleukin-1β (IL-1β), IL-2, IL-4, IL-6, IL-8, IL-10
Interleukins are a group of chemical signalling molecules. Different Interleukins have different specific effects but in general they are involved in regulating the immune system and promoting a response to infection and inflammation.

Granulocyte-colony stimulating factor (G-CSF)This is a growth factor which stimulates the development of white blood cells involved in the protection of the body against infection.

Macrophage-colony stimulating factor (M-CSF)
This is a growth factor, which stimulates the development of white blood cells involved in the protection of the body against infection.

Interferon-γInvolved in coordinating T and B cells to combat infection, particularly against viral infection but has roles against other pathogens.

Epithelial growth factor (EGF)Stimulates the production of intestinal mucosa and gut wall lining – important barriers that prevent pathogens and allergens entering a babyʼs blood stream.

Transforming growth factor-α (TGF-α), TGF β1, TGF-β2. Members of the epidermal growth factor family, thought to be involved in the maturation of the intestinal system.

Insulin-like growth factor-I (IGF-I) (also known as somatomedin C), Insulin-like growth factor- II, thought to have a role in growth promotion.

Erythropoietin, Stimulates the development of red blood cells.

HMGF I (Human milk growth factor), HMGF II, HMGF III
Thought to be involved in stimulating growth via DNA synthesis and cellular proliferation

Nerve growth factor (NGF)
β-endorphinsThought to help to overcome stress on the neonatal system following a vaginal delivery.
Parathyroid hormone (PTH)
Parathyroid hormone-related peptide (PTHrP)
β-defensin-1
Calcitonin
Gastrin
Motilin
Bombesin (gastric releasing peptide, also known as neuromedin B)
Neurotensin
Somatostatin
Platelet derived growth factors (PDGF)
Vascular endothelial growth factor (VEGF)
Hepatocyte growth factor -α (HGF-α)
HGF-β
Tumour necrosis factor-α
Peptides (combinations of amino acids)

HORMONES:

Chemical messengers that carry signals from one cell, or group of cells, to another via the blood.

Cortisol, Insulin, Thyroxine and Cholecystokinin. Help develop the baby’s intestinal system and the intestinal defence system.

Thyroxine is essential for growth, and Cholecystokinin helps with digestion, sedation, and a feeling of well-being.

Triiodothyronine (T3), Thyroid stimulating hormone (TSH) (also known as thyrotropin), Thyroid releasing hormone (TRH)
Thyroxine is essential for normal metabolism, growth and brain development. Low levels can have serious impacts on the development of the baby

ProlactinEnhances the development of lymphocytes (T and B cells) and hence has a protective role against infection.

Oxytocin. Promotes emotional connection between mother and baby. Helps them both to relax and go back to sleep after a feed at night. Also reduces the risk of bleeding following vaginal delivery by promoting contraction of the uterus.

Corticosterone
Thrombopoietin
Gonadotropin-releasing hormone (GnRH)
GRH
Leptin. Regulates appetite, food intake and energy metabolism. The higher the milk leptin concentration, the lower the infants BMI indicating that leptin could have a part to plan in preventing obesity.

Ghrelin (aids in regulation of food intake)
Adiponectin
Feedback inhibitor of lactation (FIL)
Eicosanoids
PG-E1, PG-E2. Prostaglandins, important for mounting an inflammatory response to injury and infection. They are also protective towards cells.
PG-F2

Leukotrienes, Thromboxanes, Prostacyclins
Mediators of inflammatory response required to fight infection and promote healing.

ENZYMES (catalysts that support chemical reactions in the body):

Enzymes are proteins, which lower the energy required to carry out a biochemical reaction, they are essential for every life sustaining process.

Amylase. Helps the baby to digest the starches found in milk, thought to promote better digestion of solid foods one the baby is weaned of milk.

Arysulfatase
Catalase
Histaminase
Lipase. Helps babies to digest fat when their own pancreatic function is still immature.

Lysozyme. This is found in significant concentrations in breast milk. It has both bactericidal and anti-inflammatory actions, destroying bacteria by disrupting their cell walls. Though to protect the infant against diarrhoeal diseases. It increases in concentration in breast milk as babies get older and more mobile and increases further after 12 months. It is particularly effective against E. Coli and salmonella.

PAF-acetylhydrolase
Phosphatase
Xanthine oxidase

Antiproteases. Thought to bind themselves to macromolecules such as enzymes and as a result prevent allergic and anaphylactic reactions.

a-1-antitrypsin
a-1-antichymotrypsin

ANTIMICROBIAL FACTORS: (Cellular and humoral). Used by the immune system to identify and neutralise foreign objects, such as bacteria and viruses.

In general these factors have an important role in resistance to harmful infections and training the immune system against attacking itself and causing problems such as inflammatory bowel disease, asthma and allergies.

Leukocytes (white blood cells). These are the cells found in blood which fight infections and other harmful objects

Phagocytes. These cells absorb harmful molecules and organisms and consequently destroy them, they also then have a role in protection from future infection.

Basophils, Neutrophils, Eoisinophils, Macrophages
Important in protection against infection

Lymphocytes- T cells and B cells
These cells are responsible for targeted destruction of harmful organisms. B cells produce antibodies, which give us immunity, while T cells organise the immune system into a specific infection fighting force.

Antibodies produced in human milk are highly targeted against infectious agents in the motherʼs environment. When a mother comes into contact with pathogens by either inhaling or ingesting (notably from contact with her baby’s saliva on her breast), ʻPeyerʼs patchesʼ in the lungs or small intestine manufacture specially sensitised lymphocytes (white blood cells) that then migrate to breast and create tailor-made sigA antibodies against that pathogen.
Mucosal pathogens are a major killer of children below the age of 5 years, being responsible for more than 14 million deaths annually. Diarrheal disease alone claim a toll of 5 million children per year in the developing countries.

Epidemiological data suggest that the risk of dying from diarrhea could be reduced 14-24 times in breast-fed children. A beneficial clinical effect is also apparent in the industrialised world, even in relation to relatively common diseases such as otitis media and acute lower respiratory tract infections.

sIgA (Secretory immunoglobulin A) (the most important anti-infective factor)
IgA2, IgG, IgD, IgM, IgE

Maternal immunoglobulins, these are essentially for coordinating a targeted immune response against infection and also give some immunity to infections.

Complement C1, Complement C2, Complement C3, Complement C4, Complement C5, Complement C6, Complement C7, Complement C8, Complement C9:
The complement proteins are part of the body’s defence mechanism against potentially harmful agents such as bacteria. They are involved in the detection of a harmful agent and the mobilisation of the immune system against that agent

Mucins. Attach to bacteria and viruses to prevent them from clinging to mucosal tissues

Alpha-lactoglobulin. A protein that induces death in cancerous cells (Human α-Lactalbumin made lethal to tumor cells (HAMLET)).
Some evidence to suggest that this could lower the risk of childhood cancers such as lymphoma and leukaemia.
Human milk is currently being used to develop anti-cancer drugs.

Lactadherin
Alpha-2 macroglobulin
Lewis antigens
Ribonuclease
Haemagglutinin inhibitors

Bifidus Factor
Increases growth of Lactobacillus bifidus, which is a good bacteria and protective in the gut. It encourages the growth of friendly bacterias which creates a low Ph environment in the babies gut. This discourages replication of dangerous bacteria.

Lactoferrin. Binds to iron, which prevents harmful bacteria from using the iron to grow. It is an iron-binding protein that helps the baby absorb its own iron stores but also crucially ties up the iron so it is not available to harmful micororganisms that need iron to survive. Bacteria like E.coli and Staphylococci need iron to survive and are significantly stunted in to presence of lactoferrin. As is candida which causes thrush infection.

Lactoperoxidase. B12 binding protein Deprives microorganisms of vitamin B12 (antibacterial function)

Fibronectin. Makes phagocytes more aggressive, regulates inflammation, and repairs damage caused by inflammation.