Bowel movements are not exactly dinner party conversation. You may even be too embarrassed to talk about them with your doctor. That’s a mistake, though. A change in your poop’s color might be something you ate or a medicine you’ve taken, or it might indicate a serious medical condition. Read on to find out what your poop’s color might say about your health.
What’s normal?
The brown color of normal stools come from bile salts, says Sharecare’s Chief Medical Officer Keith Roach, MD. “Bile is released by the liver and stored in the gallbladder, and then added to the small intestine just after food passes through the stomach. It helps break down food components,” says Dr. Roach.
Here’s what to watch for if your BM is suddenly showing colors of the rainbow:
Green
The cause behind green poo sounds a lot worse than it actually is. Green indicates the presence of biliverdin, says Roach. “Biliverdin is an incomplete breakdown of bile salt,” he says. That usually means food has gone through the digestive system too fast for bacteria in the intestine to change the bile from green to brown. “A very fast transit time is associated with some laxatives, as well as diarrhea,” says Roach.
A diet heavy in leafy greens can also turn your bowel movements green, according to Roach. “Especially kale, because it’s hard for your body to break down,” he says. Green food coloring can also turn your stool green, as well as certain medicines. “Iron supplements would be the big one,” Roach says.
Black
Black stool usually means there’s bleeding up high in the digestive tract, usually in the esophagus, the stomach or the small intestine. Even a bad nosebleed can cause black stool, says Roach, if you swallow enough blood. A black, tarry stool with blood in it is called a melena, he says.
Other culprits of black stool include iron supplements (again), black licorice or bismuth in the form of Pepto-Bismol. “At least once a year I have a young adult come in terrified because they have a black stool,” he says. “If they’ve taken Pepto-Bismol lately, it’s usually case closed.”
Still, there are plenty of worrisome reasons why your stool might turn black. Bottomline? Unless you’ve taken Pepto-Bismol recently and your poo quickly returns to a normal brown color, have it checked out.
Red
Red stool usually indicates bleeding in the lower GI tract. If it’s bright red, that could be from hemorrhoids. If it’s a darker red, that comes from the colon. “For colonic bleeding, we think polyps,” says Roach. “Arteriovenous malformation, or AVM, can also do it. AVM is where an artery connects directly to a vein. The structure is delicate and fragile, and when a stool passes by it, it could cause bleeding.”
Don’t panic just yet. Red food coloring can also cause red stool, but the most common cause outside of colonic bleeding is beets, says Roach. Fun fact: Beets can also turn your urine pink.
Yellow
Yellow poop, especially if it looks greasy and smells awful, means there’s a problem with fat absorption. That’s bad news, says Roach. “That usually means the pancreas isn’t working properly,” he says. “The pancreas makes an enzyme called lipase, which breaks down fat in the gut. Without that, fat comes out in your stool and when you can’t absorb fat, you lose weight to the point of malnutrition.”
Yellow bowel movements may also be a sign of celiac disease, an autoimmune disorder in which eating gluten—found in certain grains such as wheat, rye and barley – causes the immune system to attack the small intestine, interfering with the absorption of nutrients. If you’re diagnosed with celiac disease, “get on a good gluten-free diet and it will take care of the stools,” says Roach.
White
A white stool means there’s no bile salt in the BM at all. “That means there’s a blockage that is not letting the bile out,” Roach says. Bile must pass through various ducts in its journey from the liver to the gallbladder to the small intestine, and any one of those ducts could get blocked. Gallstones, cancer of the bile duct and cancer of the pancreas can all cause white stools. If your poop looks chalky, it’s almost certainly a bile duct blockage of some sort. See your doctor promptly if your BM pales in color.
