Breast milk sugar may protect babies against deadly infection

A type of sugar found in some women's breast milk may protect babies from a potentially life threatening bacterium, a new study has found.
These bacteria, called Group B streptococcus, are a common cause of meningitis in newborns and the leading cause of infection in the first three months of life globally.
The bug is carried naturally in the vagina and bowels by up to one in three women and can be transferred to the baby during childbirth or in breast milk.
The new research at Imperial College London on 183 women in The Gambia found that naturally-occurring sugars in a woman's breast milk may have protective effects against Group B streptococcus.

Each woman's breast milk contains a mixture of many different types of sugar, called human milk oligosaccharides, researchers said.
These are not digested in the baby's tummy and act as food for the 'friendly bacteria' in a baby's intestine.

The type of sugars a woman produces in her breast milk are partly dictated by her genetic make-up.
A type of genetic system in particular, called the Lewis antigen system, plays an important role in determining breast milk sugars.
The team tested all the mothers' breast milk for the sugars that are known to be controlled by these Lewis genes.
They also tested women and their babies for Group B streptococcus at birth, six days later, and then between 60 and 89 days after birth.

They found women who produced breast milk sugars linked to the Lewis gene were less likely to have the bacteria in their gut, and their babies were also less likely to get the bacteria from their mothers at birth.
In addition, among the babies who had the bacteria in their guts at birth, the infants whose mothers produced a specific sugar in their breast milk, called lacto-n-difucohexaose I, were more likely to have cleared the bacteria from their body by 60-89 days after birth.
This suggests this breast milk sugar, which is linked to the Lewis gene, may have a protective effect.

The researchers then went on to show in the laboratory that breast milk containing this particular sugar - lacto-n-difucohexaose I - was better at killing the Group B streptococcus bacteria compared to breast milk without this specific sugar.
The research was published in the journal Clinical and Translational Immunology.