"But peanuts are hardly representative of the average food. Everyone knows--via "visual observation of stool samples," to use the New England Journal of Medicine's way of saying "a glance before flushing"--that chunks of peanuts make their way through the alimentary canal undigested. Nuts are known for this. Peanuts (and corn kernels) are so uniquely and reliably hard to break down that they are used as "marker foods" in do-it-yourself tests of bowel transit time*--the time elapsed between consumption and dismissal."