The breast milk and childhood gastrointestinal microbiotas and disease outcomes: a longitudinal study.

Few studies have studied the association between breast milk microbiota and gastrointestinal microbiota beyond early infancy. The present study confirms distinct microbiota profiles in breast milk, saliva swabs, and feces in infancy and indicates increasing resemblance between breast milk and the oral microbiota by increasing age. The fecal microbiota at 3 months was associated with later allergic disease; the saliva microbiota by age 5 differed between children with and without otitis media at the same age; and children with caries by age 5 had been fed breast milk with a higher abundance of caries-associated bacteria.