I have taken it on an empty stomach, first thing in the morning and had no problems with it. Then again, when I have had a bad case of heartburn, after eating, I have taken it to help with that.
To help with digestion, I would say it is better before you eat your meal.
I guess it would depend on the 'whys' or what you feel most comfortable with. (Sounds like sitting on the fence here, huh :D)