Breastmilk protects premature babies against deadly infection – but only if it contains antibody

Breastmilk protects premature babies from a potentially deadly bacterial infection – so long as the milk contains a bacteria-binding antibody, a new study reveals. 

Necrotizing entercolitis (NEC) is the second most common cause of death for premature babies, but mother’s milk can protect them against it. 

But some infants are born so early that their mother’s breasts are not yet producing milk, so donor milk is often considered the next best choice. 

Not all breastmilk is equal though. 

In order to protect against NEC, it needs to contain the special bacteria-neutralizing antibody, and new University of Pittsburgh research suggests donor milk should be tested to ensure preterm babies bet the best protection possible.  

Breastmilk contains an antibody that protects premature infants from a deadly gut disease caused by bacteria – but some mothers of very early babies can’t yet feed. New research suggest donor milk is the best substitute, but it needs to be tested for Iga to protect babies 

On the whole, nearly 10 percent of infants that are born early develop necrotizing entercolitis (NEC), a horrific disease cause by bacteria that leads to such serious inflammation that the wall of the bowel can get destroyed. 

It’s often fatal, but breastmilk contains antibodies that bind to the killer bacteria, neutralizing them and protecting the premature baby’s gut.   

The common mantra of neonatal healthcare is ‘breast is best’ – especially the mother’s own breast. 

It’s been linked to all manner of benefits for newborns, but scientists are still in the process of working out what exactly in breastmilk is so protective, and why. 

In the case of NEC, premature babies who are fed formula, rather than breastmilk, are at between two- and three-fold greater risk of developing the devastating disease. 

Breastmilk from all mammals contains five groups of antibodies, called immunglobulins. Babies are born with only partially-developed immune systems, and these antibodies build the next phase of immunity in newborns. 

The new research suggests that one of the five, immunoglobulin A (IgA) is particularly essential to shielding the 15 million babies born premature every year from NEC bacteria.

‘It’s been well known for a decade that babies who get NEC have particular bacteria – Enterobacteriaceae – in their guts, but what we found is that it’s not how much Enterobacteriaceae there is, but whether it’s bound to IgA that matters,’ said senior study author Dr Timothy Hand, an, assistant professor of pediatric infectious diseases at University of Pittsburgh. 

‘And that’s potentially actionable.’ 

IgA and other components of breastmilk help to create a newborn’s gut microbiome. 

To assess differences between healthy preterm infants and those that develop NEC, Dr Hand and his team analyzed fecal samples from 30 such babies and 39 full-term babies. 

There they saw that samples from healthy babies contained enterobacteriaceae, but they were mostly bound to neutralizing IgA. 

IgA comes solely from breastmilk, so, unsurprisingly, the infants that were fed formula might have had the same amount of the bacteria, but they weren’t tied up by IgA. 

The scientists confirmed their work by looking at mother mice bred to produce IgA-lacking milk. 

NEC was far more common in both mouse pups fed formula and those whose mothers could not produce milk with IgA.  

In other words, breastmilk without IgA doesn’t shield newborns from NEC, but formula with added IgA may not contain the other advantageous nutrients and antibodies that are critical to a preterm baby’s survival. 

‘What we showed is that IgA is necessary but may not be sufficient to prevent NEC,’ said Dr Hand. 

‘What we’re arguing is that you might want to test the antibody content of donor milk and then target the most protective milk to the most at-risk infants.’ 

Although his research team’s findings only apply directly to preterm babies, Dr Hand says it raises broader questions about the links between breastmilk, infant health and the gut microbiome. 

‘What we’d really like to know is in the vast majority of infants what is it that this antibody doing to the infant,’ he said. 

‘Is [breastmilk] shaping the microbiome in a way that’s more diverse and better for long-term health?’ he wonders. 

‘This is evidence that mom is trying to shape the microbiome of her infants, and this same phenomenon should also work in full-term infants, toward their health.’