Mercola.com says the following about xylitol (link below):
"Studies show that prolonged use or large intake may produce the following side effects: weight gain similar to that associated with high/prolonged sucrose intake, diarrhea, tumor growth, and liver/kidney/brain dysfunction. Many manufacturers have withdrawn xylitol from their product formulation!"
It is certainly not to be consumed as a health food as all the research indicates it is not safe.
JV.
As far as I am concerned the best Sugar substitute is stevia which is positively good for you.