At the suggestion of my local brew shop I tried backsweetening with BochaSweet, which turns out to be xylose. Not sure if it affects everyone the same way, but for me, it's a VERY effective laxative. Needless to say I won't be using it again.
Xylose or xylitol? I don't think I've ever found xylose sold anywhere, but I have used xylitol without any noticeable side-effect in my ciders.