Apples and bananas help keep ME unconstipated, but for some reason "block up" my dds!??? I've heard that too that kids shouldn't eat too much of those and I don't know why!
Anyways, with my dds, I've found that peaches, blueberries, strawberries, prunes and wheat bread really help. But be warned: the blueberries, peaches and especially prunes can have quite a laxative effect if you give too much! Trust me LOL
Start off with small amounts until you find what works. They don't have to eat it everyday,but most days in my experience
Best of luck!