Welcome to BreyersYogurt.com:
"Probiotics are living microorganisms normally found in certain areas of the body, primarily the digestive tract. Humans are not born with them; we accumulate them in the gut from birth and throughout life.
Unlike the harmful bacteria that cause infections and trigger allergic reactions, probiotics actually do the opposite—they protect against harmful bacteria, in addition to helping with the many tasks involved in digestion. Probiotic bacteria even produce their own natural antibiotics, called bacteriocins, which destroy bad bacteria."