Main Page | See live article | Alphabetical index The reddish-brown color of human feces is derived from stercobilin, a tetrapyrrole chemical compound created by bacterial action on bilirubin and subsequent oxidation. External links http://www.chem.qmul.ac.uk/iupac/tetrapyrrole/TP/D6.html This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.