I'm not surprised the ginger is linked to her eating better. I have a very slow digestive tract and ginger is one of the greatest natural healers in the digestive area...if it is working don't knock it. Ginger is what the call a warming food as is cinnamon and certain other foods and ithas the effect of keeping the digestive area moving so that you don't get nausea or fullness so much so maybe your daugther is a bit the same and not feeling the hunger normally.
You can get the organic ginger which will have no sulphur or anything bad for that matter. I get mine from Macro Whole Foods. I am not sure where in Melbourne you are Kerry but there is one in Richmond, Black Rock, Glen Waverley and Brighton (I think). You would also be able to get "better" ginger from a health food store or maybe even try the Darrel Lea crystalized and ginger and see what they use.