If your baby’s in day care, you’re probably worried about all those germs her sniffly cohorts are exposing her to. Happily, a new study suggests that probiotics—those healthy gut bacteria—may help your little one escape infection.

In the best-designed study to date, infants who drank formula laced with either Lactobacillus reuteri or Bifidobacterium lactis, two commonly used probiotics, had significantly fewer episodes of fever and diarrhea than those on standard formula.

“Breastfeeding offers such protection naturally, but if your baby is on formula, adding probiotics can help—most likely by stimulating certain elements of the immune system,” says Zvi Weizman, study author and head of pediatric gastroenterology at Ben-Gurion University, in Beer Sheva, Israel. If you’re interested in giving probiotics to your baby, ask your pediatrician for dosage and brand advice.