Fructaid or Intoleran fructose dosing? Bulk xylose/glucose isomerase?

Fructaid only lists the milligrams of xylose/glucose isomerase while Intoleran only lists the IU so it's impossible to determine which one is more potent and which one is a better deal. Has anyone tried both and seen befter results with one or the other? Maybe have an estimate on how many capsules are equivalent to the other? Or has anyone bought bulk xylose isomerase from a reliable seller?