Luckily, breast milk helps not in the growth of bad bacteria rather in good gut bacteria known as "Bifidobacterium longum". B. longum is a beneficial bacterium present in human colon that ferments a wide variety of carbohydrates such as lactose and the sugars in some vegetables.

A new study shows that B. longum has successfully adapted to the unique aspect of infant's gut by producing an enzyme called LnBX that enables the bacteria to grow on sugar that is abundant in breast milk. According to Science Daily, the new study defines a symbiosis between gut microbes and humans.

Human milk sugars are known to selectively help in the growth of beneficial gut microbes such as bifidobacteria, which helps in the prevention of diarrhea and pathogenic infection in babies. The sugar present in breast milk referred as lacto-N-tetraose is broken down by bifidobacteria by producing an enzyme, this proof strongly suggests the symbiotic relationship between microbes and humans.

LnbB and LnbX are the enzymes produced by "Bifidobacterium bifidum" and "Bifidobacterium longum" respectively. These two enzymes were isolated by study authors Takane Katayama and Shinya Fushinobu from the University of Tokyo. From the tests conducted, the findings suggest that different strains and species of bifidobacteria have independently evolved molecularly to digest human milk sugar. The said finding equally describes the co-existent of these bacteria in the gut of babies feeding on breast milk.

Meanwhile, according to Power of Probiotics, "Bifidobacterium longum" is already available commercially. B. longum has anti-inflammatory properties that protect the cells from toxins. It is a probiotic that is present in breast milk and one of the first microbes to colonize the infant's gut.

The researchers plan to extend their study whether other bifidobacteria species produce diverse enzymes to digest breast milk sugars. Furthermore, the researchers will also try to find any metabolites from the said microbes promoting health to babies.