MO is likely to be a problem only if used every day, at the wrong time of day, for years. I hope that assuages your concern. I wish there were something else that would work but the very qualities of MO that you are concerned about are the ones needed to resolve this problem. See how easy it CAN be to resolve this. Something you said warned me that she might have candida complicating this problem.
Fruit is just a fun way to eat sugar.
200 years ago there was a lot of healthy things in fruit but no more. It avoids empty calories that the child will fill up on while you are trying to just offer healthy foods. Fruits are no longer healthy foods. My daughter is 8 and has constipation problems. This will work as well for her.