This version is aimed at Health Professionals or anyone wanting more detail. There is a shorter version for parents here

Exclusive Breastfeeding and Why…

by Charlotte Young, iwantmymum.com

Many of the health reasons cited for breastfeeding require exclusive breastfeeding, which means solely breastmilk. No water, solids or formula. Current guidelines by the UK Government, the World Health Organisation (WHO) and UNICEF are to breastfeed exclusively for 6 months – why?

A newborn’s gastrointestinal tract is sterile; there are no bacteria or other microbes. If born normally, a baby is exposed to his mother’s bacteria first and has protection from antibodies delivered via the placenta. As baby breastfeeds, he receives additional antibodies from colostrum and breastmilk.

If babies are born by caesarean section however, they are likely to be initially exposed to environmental microbes from the air or hospital staff. As mum may not carry antibodies to these foreign microbes, baby is more vulnerable to infection. Other babies at greater risk are preterm infants, and full term infants with any condition that requires separation from their mother or the giving of a breastmilk substitute.

The immune system of a baby is very different from that of an older child or adult. There are three main immunoglobulins and only one crosses the placental barrier, providing baby with some immunity at birth to specific viral infections. The other two take several years to reach adult levels; IgA in particular is at very low levels in the newborn and develops slowly.

In addition to a lack of antibodies, the infant’s system has immature immune responses to specific antigens. What makes babies even more vulnerable still is that until around six months of age they have what is often referred to as an “open gut”. This means the spaces between the cells of the small intestine will allow large molecules to pass directly into their bloodstream.

Because of all these factors, neonates demonstrate a marked susceptibility to infections, particularly those which gain entry through the mucosa of the respiratory and gastro-intestinal systems. So minor infections have the potential to become generalised very easily.

Human infants are meant to drink human milk; there are very good reasons for this. Firstly it is rich in immunoglobulins, providing the infant with passive immunity until his own system is mature enough to take over. IgA is at higher levels than others, perfectly complementing baby’s own low level.

Mum also creates antibodies specifically tailored to protect against pathogens acquired from her baby’s immediate surroundings. New antibodies are produced whenever she comes in contact with harmful microbes, or when baby breastfeeds, passing into mother’s body via saliva on her nipple. This signals her immune system to provide or produce the antibodies, which are passed back at subsequent feedings.

If baby is not breastfeeding, he has only his own very low antibody levels support him; this, compounded by an immature immunological system, make him extremely vulnerable to infection.

If breastmilk is all that has ever entered baby’s gut, it is often referred to as a “virgin gut”. This is because it is a unique environment only found in an exclusively breastfed baby.

Antibodies and other constituents of breastmilk create this environment. Acidity levels differ dramatically from than of a non breastfed baby and so does the profile of bacteria present. Positive bacteria thrive, aiding digestion and interfering with the growth of pathogenic bacteria. In this environment, the immunoglobulins mum passes are not destroyed in the gut; instead IgA coats the mucosal surfaces, preventing harmful pathogens from being absorbed into baby’s bloodstream. These antibodies “ignore” good bacteria, but cling to and destroy harmful pathogens (disease causing microbes). In basic terms they “seal” the open gut from harmful bacteria, whilst allowing beneficial constituents to move freely. Other antibodies enter the bloodstream, moving throughout the body, and searching for any foreign substances that may cause harm. This serves as a first line of defence and assists the immature immune system.

Whereas the “open gut” is of benefit to the breastfed baby, allowing antibodies to slip easily into the blood stream, in the artificially fed infant it only serves to allow less desirable microbes such as pathogens or potentially harmful food proteins to enter directly into baby’s bloodstream.

Only small amounts of formula or solid foods cause a shift that destroys this environment, changing acidity and destroying the immunoglobulins that coat mucosal surfaces. Just one formula supplement per 24 hours will result in an almost immediate shift from breastfed to formula-fed gut flora - in which good bacteria (Bifidobacteria) are no longer dominant. (Mackie, Sghir, Gaskins, 1999. Bullen, Tearle, Stewart, 1977)

Following formula supplementation, even if breastmilk was given exclusively again, thereafter it would take 2-4 weeks for the intestinal environment to return again to a state favouring Grampositive Flora .(Brown & Bosworth, 1922; Gerstley, Howell, Nagel, 1932). If breastmilk subsitutes are used in the first few days postpartum, the gut flora may never reach normal levels.

The introduction of solid food also causes a major shift in the gut ecosystem, with a rapid rise in the number of Enterobacteria (which can cause for example Salmonella and E-Coli) and Enterococci (an extremely antibioticresistant germ responsible for infections including urinary tract infections and meningitis). This is followed by progressive colonisation of Bacteroides (extremely antibiotic resistant, generally opportunistic germs which can cause a variety of infections throughout the body), Clostridia (which cause for example tetanus, botulism, diarrhoea and colitis and Clostridium difficile (C.DIFF) which can cause infection and diarrhoea.

Around the middle of the first year, in readiness for the introduction of solids, the spaces between the cells of the small intestines are reduced (“closed gut”), thus preventing large food proteins entering the bloodstream. Introducing foods that are sources of “good bacteria” or encourage them to thrive (alongside breastmilk) is important to continued health.

Constituents that actively assist an infant in fighting disease:

Stem Cells: Have a remarkable ability to develop into many different cell types in the body, serving as a sort of internal repair system. Stem cells from other sources (see link above) are already being used to treat leukaemia and could soon help treat eye conditions. Scientists are also researching their potential in the longer term for treating conditions such as spinal injuries, diabetes and Parkinson’s disease

Lysozyme: This enzyme enhances the ability of IgA to fight against certain disease-causing organisms

Oligosaccharides: These are molecules which prevent harmful bacteria from multiplying and causing an infection. They bind with bacteria, forming a compound that the baby excretes from the body.

Milk lipids (fats): Milk lipids damage the outer surface of certain types of viruses. When the viruses are damaged, they are unable to replicate and cause an infection in the baby.

Immunoglobulins: IgA, IgG, IgM and IgD are all found in human milk. Of these the most important is IgA, which appears to be both synthesised and stored in the breast. It ‘paints’ the intestinal epithelium and protects the mucosal surfaces against entry of pathogenic bacteria and enteroviruses. It affords protections against E. coli, salmonellae, shigellae, streptococci, staphylococci, pneumococci, poliovirus and the rotaviruses.

Proteins: A protein called Lactoferrin is present in breast milk. When this protein binds to iron, it prevents disease-causing bacteria from consuming it. Bacteria need iron to survive. Therefore, lactoferrin helps kill the bacteria and infection is prevented. It also helps prevent the immune system from overreacting. Lactoferrin is currently being investigated as a treatment for auto-immune conditions, such as rheumatoid arthritis, multiple sclerosis and septic shock.

Researchers have isolated a protein called alpha lactalbumin in breastmilk. When this is mixed with oleic acid (found in breastmilk and the gut of an exclusively breastfed infant) it creates what they have named HAMLET (Human Alpha lactalbumin Made LEThal to tumours). In fact this protein can destroy over FORTY types of cancer.

Another protein called Mucin is present in breast milk. Mucin attaches to bacteria and viruses that enter the baby’s body. When this happens, other cells in the immune system will destroy the disease-causing substance.

Cytokines are believed to play a significant role in the immune-modulation and immune-protection of breast milk. Most of the cytokines that are known to be deficient in the neonate have been found in significant amounts in breast milk

Fibronectin and Interferon also help destroy viruses that enter the baby’s body.

Anti-infective factors: During the first 10 days there are more white cells per ml of human milk than there are in blood.

Macrophages and neutrophils are amongst the most common leukocytes in human milk, and they surround and destroy harmful bacteria by their phagocytic activity. The macrophages also manufacture lysozyme, increasing its amount in the infant’s gastrointestinal tract. Lysozyme is an enzyme that destroys bacteria by disrupting their cell walls. Macrophages in the digestive tract can rally lymphocytes into action against invaders

Lymphocytes give rise to antibodies and kill infected cells directly or send out chemical messages that mobilise still other components of the immune system (see T cells).

T cells are a sub-group of lymphocytes that play an important role in establishing and maximizing the capabilities of the immune system. These cells are unusual in that they have no cytotoxic or phagocytic activity; they cannot kill infected host cells (also known as somatic cells) or pathogens, and without other immune cells they would usually be considered useless against an infection. T cells are involved in activating and directing other immune cells, and are particularly important in the immune system.

Linoleic acid: Associated with anti-cancer properties, can reduce the risk for cardiovascular disease and help fight inflammation.

Today, some patients suffering from immunological diseases - such as HIV, leukaemia or hepatitis - or those receiving therapy that reduces the immune system, such as chemotherapy, are drinking breast milk in the hope that it can help adults, just as it helps sick babies.

It has also been taken by cancer patients who claim it slows the progression of the disease and in the U.S., some milk banks provide it to adults with a prescription from their doctor.
Supplementation of the Breastfed Baby: “Just One Bottle Won’t Hurt”—or Will It? by Marsha Walker, RN, IBCLC

WHO: The Optimal Duration of Exclusive Breastfeeding: A Systematic Review WHO/NHD/01.08 (2002)

http://en.wikipedia.org/wiki/Gut_flora

http://www.gentlebirth.org