Hydrogen breath test..

Question for those who have had this test or know more about it than me (prettysoulful?)

My doc agreed to order me the test and before I schedule I was wondering is there an optimal time of day to take this test and should I fast or should I eat things that would normally cause a flare? I want the test to be accurate of course but these dr.s and lab techs dont seem to know much about particular parameters for such tests.

thanks