Probiotics—those bacteria that are good for your digestive tract—are short-lived, rarely taking residence or colonizing the gut. But a new study from researchers at the University of California, Davis, finds that in breast milk-fed babies given the probiotic B. infantis, the probiotic will persist in the baby’s gut for up to one year and play a valuable role in a healthy digestive system. The study was published in the journal Pediatric Research.