system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does poop turn brown no matter what color food I eat?
gpt
Drink a litre of Powerade, it will change. 

Brown is the normal color of poo. There is a pigment called bilirubin that is formed when the red blood cells in the liver and bone marrow break down. This ends up (by a complicated process) in the intestines where bacteria begins to form and eat which turns the poo brown.