Bleeding in the gastrointestinal tract and colon cancer can cause black poop (also known as melena). But black stool doesn't always mean there is an underlying health concern. Dark-colored foods, iron ...

Here's what you need to know: Is it OK if your poop is green? According to mayoclinic.org, all shades of brown and even green poop are considered to be normal. It is rare for the color of your poop to ...