I've been aware of this debate (whether nutritional yeast is good or bad for you) for years. I was told that contemporary nutritional yeast is different in kind than the old Brewer's yeast I was given as a child -- that the yeast-promoting elements have been removed, and the nutrients remain. Who knows. I was also told that the Europeans feel more comfortable using nutritional yeast then we do. They don't worry as much about it increasing a yeast/Candida problem. They find that it is health promoting.
Meanwhile, I learned muscle-testing from taking an applied kinesiology class (hope I'm spelling that right) and learned how to use a pendulum. I use both those methods to determine whether a substance strengthens or weakens my system. Strangely enough, Dr. Schulze 's Superfood only checks out positively for me if I add more nutritional yeast to it. Otherwise, I get a bit unbalanced and irritable. So there you go. Different strokes for different folks.