Final answer:
Bilirubin is a brown pigment secreted into bile by the liver. It is a waste product of red blood cell breakdown and gives stool its characteristic color. In certain diseases, it can affect the color and content of stool.
Step-by-step explanation:
Bilirubin is a brown pigment that is secreted into bile by the liver. It is a byproduct of the breakdown of red blood cells and is excreted in feces. Bilirubin is responsible for the green color of bile, and it is eventually transformed into stercobilin, a brown pigment that gives stool its characteristic color.
In some disease states, bile does not enter the intestines, resulting in white stool with a high fat content.