what leavening brings to flour, nutrition-wise
So I was reading "Cooked" by Michael Pollan, which is a wonderful book about the natural history of food preparation. He has a long chapter about bread. He begins with a remarkable thought. He quotes a food chemist at UC Davis saying that you could not survive on wheat flour, but you could on bread. There is no elaboration given to this, but it seems that the reason is something like the microbial action of the yeast (and sourdough in particular) renders the flour more digestable. Does anyone have any biochemical insight about that? References perhaps? I find that kind of remarkable. I mean, in what way can our bodies not completely digest unleavened flour?