The mysteries of breast milk

We know more about the composition of coffee and meat than we do about our first and most important food: breast milk. But scientist Dr. Eleni Tsompanidou is overturning popular knowledge about breast milk bacteria. ‘Bad bacteria does a lot of good.’
By Tatiana Coba

Two years ago, microbiologist Eleni Tsompanidou gave birth to her second child at the University Medical Center of Groningen (UMCG). In the IC maternity ward she overheard a conversation between expectant mothers who had decided not to breastfeed their babies. They were worried that breastfeeding would change the appearance of their nipples.

At that moment, Tsompanidou knew she wanted to research the benefits of breastmilk, and use her research to educate mothers. ‘These women actually put appearance ahead because they didn’t realize why breastfeeding is so important’, says the Greek researcher.

Fresh sample

With the assistance of her student, Melanie Prins, Tsompanidou analyzed the bacteria in eleven samples of breast milk at the UMCG laboratory. Once a week, Prins picks up a fresh sample of breast milk from a local mother. She packs the bottle in ice and rushes it back to the UMCG on her bike. ‘The fresher the sample, the better’, she explains.

‘When I learnt Eleni was conducting research on breast milk, I immediately felt like taking part in it. As a mother I was very misinformed about this subject. There is a huge need for more evidence-based sources, so any effort to understand better breast milk is very important to make better informed choices’, says Sílvia Fernandes, one of the breast milk donors.

Not so fast

At the lab, Prins carefully extracts the milk and pours it, painstakingly, into different containers; too much force or velocity will ruin the sample. Tsompanidou then spreads the liquid onto glass petri dishes. Tsompanidou lets the milk bacteria grow in the petri dishes for two weeks before she analyses it.

Her findings are surprising, and fly in the face of popular knowledge: first, the samples show that not all bacteria in breast milk are ‘good’ bacteria; and second, they reveal that the mother’s gut is not the only source of bacteria, as previously believed.

Immune system

Breast milk bacteria can help train an infant’s developing immune system. But it’s interesting to see  that ‘not all bacteria passed in the breast milk are good bacteria; there are also really low quantities of bad bacteria. These kinds of bacteria in the milk says to the baby’s system “I am good, you have to keep me, or: I am bad, you have to attack me”’, explains Tsompanidou.

‘Their goal is to train the immune system of the baby, so that later in life, when the real ´bad guys´ want to attack the kid, the body already knows how to fight them’, she adds.

Also, breastfeeding helps the baby to fight common diseases by providing ‘reinforcements’. When a baby contracts a cold, his saliva passes that information to the breast; magically, the mother’s body responds by producing antibodies.

Extra support

These are then administered to the baby via breast milk. ‘It is like an extra support for the baby to fight diseases’, explains Tsompanidou. For this reason, she recommends mothers breastfeed as long as they can.

Moreover, breast milk provides human milk oligosaccharides (HMO), ‘food’ for good bacteria like bifidobacterium. Studies have shown that HMOs can shorten the duration of rotavirus infection, a leading causes of severe diarrhea in infants.

The source of the bacteria present in breast milk is a controversial topic in this field. A popular theory suggests that maternal gut bacteria passes through the breast to the baby, but Tsompanidou’s findings contradict that theory.  Most of the bacteria in breast milk comes from the infant’s mouth and the mother’s skin — not the gut.

Only one sample

‘From eleven samples, only one sample had gut the bacteria bifidobacterium and lactobacillus. But in all eleven we found oral and skin samples’, she says.

A more precise understanding of  breast milk microbiota brings us a step closer to promoting a healthy gut and improving the infant immune system — a benefit that lasts a lifetime. This makes babies better at fighting skin diseases, asthma, type 1 diabetes and several autoimmune diseases.

Fifteen years ago, scientists believed breast milk was almost sterile, or at least free from bacteria or other living microorganisms. This led them to underestimate the importance of breast milk for human development.

But now, thanks in part to Tsompanidou, the the scientific community is more able than ever to have a ‘significant impact on health, not only in infancy and childhood, but also later on in life’.

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