system
Given the following post, respond as if you're commenting on Reddit:
human
Why is poo almost always brown, regardless of what we eat?

Edit: judging by the notifications I'm getting to my phone, the moderators are doing a hell of a job keeping this thread clean. You have my appreciation, mods!
gpt
The brown color of feces comes from the pigment stercobilin, one of the final products of heme (red blood cell) breakdown. Urobilin is similar; it also comes from heme catabolism. However it is yellow and excreted in the urine due to high water solubility. Changes in fecal color can indicate a wide range of issues, in the appropriate clinical context.