as some of the others stated, prune juice is best for babies.
My child experienced severe attacks , she was bent over in pain screaming, and crying.
I was told by a doctor to give one teaspoon of mineral oil to relieve the painful cramps and it would lubricate the bowels and this will stop the cramping and helps them to go fast.
Babies are more sensitive and you must be careful with the juices, don't over do it because you could start a diaper rash from all the acid in the juices. prune juice once a week is good enough. Older ones, I gave a little mineral if I seen signs starting to arise. And of course, continue to give them healthy foods with fiber. (Oatmeal with raisins is good choice)