Researchers have discovered that a certain sugar found in breast milk may have protective benefit against the bacteria Group B streptococcus, which is a common cause of meningitis in newborns.

One in three women carry the bacteria and it can be passed on to a baby during childbirth or when breastfeeding. For a study published in the journal Clinical and Translational Immunology, Imperial College London researchers worked with 183 women from The Gambia and found that a breast milk sugar called lacto-n-difucohexaose I may have a hand in protecting newborns against Group B streptococcus.

Breast milk contains different types of sugar known as oligosaccharides. When consumed by a baby, these sugars are not digested, instead acting as food for friendly bacteria in their gut.

The exact combination of sugars found in breast milk will vary from woman to woman because human milk oligosaccharides are partly dictated by a woman's genes. There's a particular genetic system, though that aids in determining sugars found in breast milk known as the Lewis antigen system.

For the study, the researchers tested breast milk from the subjects for sugars known to be controlled by Lewis genes. The subjects and their babies were also tested for Group B streptococcus first at birth, then after six days, and then 60 to 89 days after the birth.

They found that those women with breast milk sugars associated with Lewis genes were not only less likely to have Group B streptococcus bacteria, but also had babies who were less likely to acquire the bacteria at birth.

Additionally, those babies who have acquired the bacteria at birth but have mothers who produced the breast milk sugar lacto-n-difucohexaose I were likelier to have flushed out the bacteria from their bodies within 60 and 89 days of being born. This suggests that the breast milk sugar offers protective benefit against the bacteria.

When the researchers specifically tested the effects of the breast milk sugar on the bacteria, they discovered that it does work better at wiping out Group B streptococcus than breast milk without lacto-n-difucohexaose I.

The breast milk sugar was also found to be an effective decoy, tricking the bacteria into thinking it's a human cell it can latch on to. And when it does so, it is promptly excreted from the body. This helps in clearing the Group B streptococcus' presence in the baby's gut, allowing friendly bacteria to flourish.

"Although this is early-stage research, it demonstrates the complexity of breast milk, and the benefits it may have for the baby," said Nicholas Andreas, the study's lead author.

Photo: Bridget Coila | Flickr

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