Hi there. Yes, I've read that things like that can result in behavioral issues. Your hands are tied though if her mom won't alter her diet. Sadly, it sounds like it is too disruptive to continue watching her. I'd give the mom notice to begin looking for another arrangement. good luck
Some foods have been known to trigger behavior issues. You might want to get this issue checked out by your child's pediatrician. However, it sounds as if your child is making a conscious decision to misbehave. It definitely sounds as if discipline is warranted.
She's the baby sitter Marklakewood. The mother of the child will not alter her diet to even find out if it has an effect. That is an unworkable situation.