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Breastfeeding, bacteria and your baby's gut

Does your baby like to pick up anything and everything and put it into her mouth? You know what? This may actually be a way to keep her healthy!

Breastfeeding and bacteria. It may not be a combination you may think of as being important for a new baby. But it actually may be very important.

In 2003, scientists completed the Human Genome Project. It was thought that this project would help us understand how genes are connected to disease thus offering science a new way of preventing and treating disease. It was expected that humans would have about 100,000 genes but it was discovered that we only have about 20,000 genes (about the same as a basic roundworm!). In fact, the gut microbiome in our body is far more complex than our genetic makeup. The gut microbiome is the collection of healthy microorganisms, such as bacteria, that live in the gut. About 90% of our cells are of microbial (eg bacterial) origin, and only 10% of human origin. We are actually far more bacterial than human.

More and more research is showing how our gut microbiome may play an important role in many aspects of our physical and emotional wellbeing. It seems that our gut microbiome may be able to influence many cells of our body and in doing so influence our overall health. An unhealthy and less diverse gut microbiome has been observed in a number of conditions including obesity, diabetes, metabolic syndrome and allergy.

Our environment and events that do or don’t occur, especially in our early years, can influence our gut microbiome. Inheritance is so much more than about what we inherit from our parents. Our gut microbiome has the potential to influence which genes are switched on and which are switched off. Some genes may even be switched on a little, right up to a lot.

Also, our genes carry ‘memories’ from past generations (called ‘epigenetics’). So, who we are today is a result of who our past generations were – up to three generations back at least! So what we do in our lifetime can potentially influence our children, their children and so on.

Our first dose of bacteria is received while we are inside our mother’s uterus (even the placenta has its own microbiome) then via our mother’s vaginal and intestinal microflora (if we are born vaginally) and finally via breastfeeding and skin-to-skin contact. The microbiome of a baby born vaginally is more diverse and healthy as compared to that of a baby born via caesarean section.

Significant differences exist in the gut microbiota of babies exclusively breastfed compared to those given formula. Exclusive breastfeeding helps a baby to develop a healthy and diverse gut microbiome. Bacteria (probiotics) from the mother get passed on to the baby during breastfeeding (from the mother’s skin and her breastmilk).

Breastmilk contains about 200 different types of oligosaccharides (prebiotics), which provide food for the good bacteria in the gut.

Who would have thought bacteria could be such a good thing?


© Australian Breastfeeding Association July 2019


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Last reviewed: 
Aug 2019