Fructooligosaccharides are put in probiotics to (supposedly) feed the beneficial bacteria. My daughter's pediatrician recommended a brand of probiotic with it in it (HMF), but I have been doing research on FOS because I've heard conflicting info about it. Some sites states that it might not be beneficial and can feed harmful bacteria like Klebsiella.

Anyone have an opinion on this?

There are probiotics made without it, but they're definitely more difficult to find. My daughter's pediatrician also said to get her an L.reuteri probiotic, but the ones at the health food store has FOS.