A lot, actually.
The usual brown color of stool is a result of your body breaking down the hemoglobin lost by dying red blood cells.
If, for example, a patient were in liver failure
, this breakdown would not occur and the stool would be much more pale in color. There are many other conditions which can change stool color
. Not to mention, the body may struggle to absorb food colorings and dyes (think kids' cereal).
Answer assisted by Cole Livingston, Medical Student