Black or Tarry Stools UF Health Melena vs hematochezia symptoms and differences Healthy Poop Chart: Is Your Poop Normal? Nikki Yelton RD Stool Colors and What They Can Tell You Your stool color can carry important clues about digestion, diet, or even disease. Most shades are harmless, but some changes signal the need for 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. A Quick Guide to Stool Color and What They May Mean NaturWarriors