That really interesting; in my personal experience, if I let my kefir culture to the point where it separates and becomes bitter, it seems to have a not-so-good effect on me. However, if I let it culture just to the point where it doesn't separate but has that slightly sweet flavor, it works great on my digestion. I have also read elsewhere that you shouldn't let your kefir culture to the point of separation. So there may be some truth to what this person is saying.