Although mothers today commonly opt to breastfeed their babies, many infants are still fed formula. Now, a study published online in Pediatric Research last December suggests that soy formulas may inhibit intestinal development in babies.

During animal studies, researchers determined that many common soy formulas on the market today contain high concentrations of an isoflavone called “genistein,” which may put babies at risk. In fact, the study authors found that genistein levels in some formulas were higher than those proven to affect menstrual levels in women. The study concluded that, while clinical data suggest that soy formula is safe, it is not “without effect.”