Breast Milk Antibodies

By Krista Gray, IBCLC. Last updated July 28, 2017.

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You may have heard that breast milk has living antibodies that help protect your baby from getting sick.  It’s true!  But, how does all of that work and how can you maximize the specific antibodies your baby receives?

How it works

Immunoglobulins in breast milk produce an antibody response specific to the germs and bacteria you and your baby contact.  The most famous one is sIgA, though there are several that do this amazing work. When a mother comes into contact with an antigen (whether she contacts it directly or her baby has come into contact with it and her body picks up on this from touching her baby and receiving these germs from him) her body immediately goes to work.  Cells in a mother’s body carry these invader germs to either the respiratory or intestinal tracts where her body works fast and furiously to produce IgA antibodies that are specific to exactly what she has come into contact with.  Once this antigen response has been made it travels to the mammary glands where your baby receives specific protection in the breast milk. 1  Secretory IgA lines your baby’s intestinal tract, urinary tract, and oral pharynx and helps fight these harmful pathogens.

How long does it work

When a baby is born, his immune system and gastrointestinal tract are immature.  Ideally, they will receive breast milk alone for the first six months of life, which coats, protects, and allows these systems to mature.  A newborn baby’s own IgA system is deficient and unable to make this antibody response in the beginning.  His body slowly matures and gains this ability, though it develops more slowly and great harm can be caused when foreign substances (including formula) pass through a baby’s immature system. 2 Babies need this protection from breast milk; and it cannot be replicated in formula since it is not a living, changing substance.

In short, sIgA is found in high levels in colostrum (a baby’s first milk to coat his system) and protection to your baby begins immediately upon commencing breastfeeding!  Even better, the protection doesn’t slow down during the duration of nursing.  As a mother’s body makes more milk, the dose of sIgA increases so that the level your baby receives remains constant throughout the duration of breastfeeding. 3 So no matter how long you breastfeed your baby, there will always be these amazing antibodies in your milk specific for your child.

How can I maximize protection for my baby?

In order for your body to make specific antibodies, you need to come in contact with the pathogens.  If you know your baby has been around a person who has a cold, for example, rather than washing your hands and your baby immediately following exposure, scoop your little one up, touch him, kiss him, nurse him. Make sure whatever he’s come into contact with you also touch.  Then your body will go to work and start the incredible process of making milk with antibodies specific to that pathogen.

Think about it, when your baby is small you can protect him more from many germs, but his immune system is also weaker and he needs protection from your milk.  As he grows, he begins to explore his world and put everything in his mouth.  Once he’s at play groups, nurseries, or friends’ homes, he is coming into contact with so many new pathogens every day!  He continues to need your amazing milk to help him have a quick response with specific antibodies.  His system could become tired and worn down, if his growing body is left to do it on his own. Or, if he’s still a young baby his system will be too immature to be capable of producing this immune response at all.  But together, through your breast milk and his maturing body, you make a great team providing optimum protection from sickness as he grows.

So as your baby grows and plays with other children and toys, rather than taking him straight home for a bath why don’t you spend time together cuddling and making sure your body picks up on everything he came in contact with before washing it all off?  Typically your baby will come in contact with much more than you because he plays with more and puts so much in his mouth. If you will take time to touch what he played with (perhaps while you are helping to tidy up?!) and then nurse your baby, your body will be set and immediately go to work making an immune response in your milk.

How awesome is that? Definitely another reason to breastfeed your baby!

Show 3 footnotes

  1. Riordan, J. & Wambach, K. (2010) Breastfeeding and Human Lactation, 4th ed. Jones and Bartlett Publishers, Sudbury, MA pp. 142-3.
  2. Rabet, L.M., et al. (2008) Breast-feeding and its role in early development of the immune system in infants: consequences for health later in life. Journal of Nutrition, vol. 138, no. 9 1782S-1790S
  3. Riordan, J. & Wambach, K. (2010) Breastfeeding and Human Lactation, 4th ed. Jones and Bartlett Publishers, Sudbury, MA p.143