Liquid Gold: Breastfeeding & the Gut

Written by Clare Carrick ANutr (BHSc)

Scientifically reviewed by Dr Fathalla Ali, PHD Paediatrics


Breastfeeding is hard. Not enough people talk about how hard it can be. 


Sure, some people seem to be able to whip out a boob, stick it in their baby’s mouth and be on their merry way…There’s even some pretty incredible photos of yoga mums breastfeeding whilst doing the standing splits pose…but this is not reality for the majority of us. For most women, breastfeeding will look more like long days stuck under a baby on the couch, milk-stained clothes, sore nipples, trying out all the different breastfeeding ‘holds’, and worrying about whether there’s too much, or too little, milk…


We’re often told ‘breast is best’, but the reasons behind this are not always made clear! If you’re currently sitting on the fence about breastfeeding, or you’re planning on having a baby soon, here is some of the science behind what breastfeeding can do for your baby. Knowledge is power, and being equipped with this scientific information can help empower you to make a choice that will help you, and your baby, thrive. 


What Breastfeeding Does for Your Baby

Exclusive breastfeeding is recommended for about 6 months of life, and then alongside the introduction of solids for at least one year (1). These recommendations have been made because of the positive impact that breastfeeding has on both the mother and the baby’s health (1). Far from purely being a source of energy for your baby, breastmilk offers nutrients, immune-supporting components, and bioactive substances, all of which will help to protect your baby now, encourage healthy growth and development, and reduce their risk of developing disease later in life (2).  


Breastmilk and Your Baby’s Gut

Breastfeeding helps to continue the microbial connection between mother and baby, post birth, and propels the colonisation of baby’s microbiome (2). Breastmilk itself is host to its own microbiome, and contains substances that promote the growth and abundance of beneficial microbes in baby’s gut (2). 


Microbes love Breastmilk

One important substance in breastmilk are the Human Milk Oligosaccharides (HMOs) (3). HMOs ‘feed’ some of the most beneficial species of gut bugs, Bifidobacteria and Bacteroides, helping them to thrive and multiply within your baby’s gut (3, 4).  Bacteroides is vital for breaking down fibre, and its presence helps with the stability and adaptability of the infant gut (4). Bifidobacteria is famous for its important role in early infant growth, microbiome establishment, and immune system development, so there’s many reasons to love these bugs (5)! In addition to the benefits of the Bifidobacteria itself, scientists have identified a by-product, known as aromatic lactic acid, which also has positive effects on baby’s health (3). These aromatic lactic acids are produced when specific strains of the Bifidobacterium species ‘feed on’ the HMOs in the breastmilk…so it’s sort of like the ‘waste product’ of the Bifidobacterium feast…except that it’s not waste at all (3)! In fact, these Bifidobacteria-derived  aromatic lactic acids also seem to contribute to immune health, and help to maintain the internal balance in the body, otherwise known as ‘homeostasis’ (3).   


Breastfeed, If You Can

Of course, for a variety of reasons, breastfeeding is not always possible. It is important to recognise that breastfeeding is just one of many variables along the twisted path of parenthood, and is certainly not the be-all and end-all to your baby’s health! 

If, however, breastfeeding is possible for you, rest assured that your efforts are not going unrewarded, even if it does feel like it sometimes! And, in those 3am feeds, when it can feel so quiet and lonely, know that your milk is providing your baby billions of microbial friends that will help support and nurture your bub for the rest of their lives. What a gift!


  1. Lessen R, Kavanagh K. Position of the academy of nutrition and dietetics: promoting and supporting breastfeeding. Journal of the Academy of Nutrition and Dietetics. 2015 Mar 1;115(3):444-9.
  2. García-Mantrana I, Bertua B, Martínez-Costa C, Collado MC. Perinatal nutrition: How to take care of the gut microbiota?. Clinical Nutrition Experimental. 2016 Apr 1;6:3-16. 
  1. Laursen MF, Sakanaka M, von Burg N, Mörbe U, Andersen D, Moll JM, Pekmez CT, Rivollier A, Michaelsen KF, Mølgaard C, Lind MV. Bifidobacterium species associated with breastfeeding produce aromatic lactic acids in the infant gut. Nature microbiology. 2021 Nov;6(11):1367-82. 
  2. Marcobal A, Sonnenburg JL. Human milk oligosaccharide consumption by intestinal microbiota. Clinical Microbiology and Infection. 2012 Jul 1;18:12-5.

Bittinger, K., Zhao, C., Li, Y., Ford, E., Friedman, E. S., Ni, J., Kulkarni, C. V., Cai, J., Tian, Y., Liu, Q., Patterson, A. D., Sarkar, D., Chan, S., Maranas, C., Saha-Shah, A., Lund, P., Garcia, B. A., Mattei, L. M., Gerber, J. S., Elovitz, M. A., … Wu, G. D. (2020). Bacterial colonization reprograms the neonatal gut metabolome. Nature microbiology, 5(6), 838–847.

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