@szelisk If you don’t mind my asking, how old are you? The reason I ask is because Microscopic colitis was first discovered in the mid-70’s, when the first sub-type (collagenous) was identified). The second (lymphocytic) was identified in 1989. I point this out because the study you refer to is not a major study. It is only one study. Microscopic colitis went for decades after it was identified still being relatively unknown to many doctors, mainly because it’s associated with women. I’ve had it for 35+ years. I am now in my 70’s. I have followed these “studies” and not much research until fairly recently has been done, most still hypothesis. I have collagenous colitis but it is not anywhere in my family history- near or far.