This is the main friendly intestinal bacteria in breast-fed infants. It is able to outgrow potentially pathogenic organisms and has a role in reducing enteric upsets in infants.This probiotic bacterium is a specific inhabitant of the large intestine (colon) where it can be found at high concentrations in infants. This species is predominant in the feces of breast-fed infants. Like other bifidobacteria species, this organism produce acids that may retard the colonization of the colon by certain foreign or harmful bacteria. Research suggests that the presence of Bifidobacterium infantis in the colon helps reduce the incidence of infantile diarrhea.

Produces acetic acid and lactic acid, which lower the pH of the intestine and inhibit growth of undesirable bacteria. Acetic acid has a stronger antagonistic effect against gram-negative bacteria than lactic acid. These acids decrease the pH and inhibits the growth of pathogenic bacteria including Candida albicans and E.coli. They prevent the colonization of the intestine by invading pathogens by competition for nutrients and attachment sites to the epithelial surfaces.