Types of Poop: What Doctors Need You to Know The Healthy @Reader's Digest A change in the colour of one's stools may sometimes be due to dietary changes; though it could also reveal something about one's health. Where stool appears or , it Hematochezia vs melena: Comparing symptoms, causes, and treatment Dark stool vs black stool the difference can be serious. Dark brown stool is often food or iron related. Black, tarry stool may indicate internal bleeding and needs urgent medical attention.