Yellow: Greasy, foul-smelling yellow poop indicates excess fat, which could be due to malabsorption disorder like celiac disease.
Black: It could mean that you are bleeding internally due to ulcer or cancer. Some vitamins containing iron or bismuth subsalicylate could cause black poop too. Pay attention if it’s sticky and see a doctor if you have any concerns.
Light-colored, White, or Clay-colored: It could mean a bile duct obstruction. Some medications can also cause your poop to be white.
Blood-stained or Red: Blood in your poop can mean you have cancer. ALWAYS see a doctor right away if you have red in your stool.