Breast Milk Sugars Give Infants a Protective Coat
A large part of human milk cannot be digested by babies and seems to have a purpose quite different from infant nutrition — that of influencing the composition of the bacteria in the infant’s gut.
The details of this three-way relationship between mother, child and gut microbes are being worked out by three researchers at the University of California, Davis — Bruce German, Carlito Lebrilla and David Mills. They and colleagues have found that a particular strain of bacterium, a subspecies of Bifidobacterium longum, possesses a special suite of genes that enable it to thrive on the indigestible component of milk.
This subspecies is commonly found in the feces of breast-fed infants. It coats the lining of the infant’s intestine, protecting it from noxious bacteria.
Infants presumably acquire the special strain of bifido from their mothers, but strangely, it has not yet been detected in adults. “We’re all wondering where it hides out,” Dr. Mills said.
The indigestible substance that favors the bifido bacterium is a slew of complex sugars derived from lactose, the principal component of milk. The complex sugars consist of a lactose molecule on to which chains of other sugar units have been added. The human genome does not contain the necessary genes to break down the complex sugars, but the bifido subspecies does, the researchers say in a review of their progress in today’s Proceedings of the National Academy of Sciences.
Breast Milk Sugars Give Infants a Protective Coat - NYTimes.com
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