Normal poop is brown. The shade can range from light tan to dark chocolate, and all of those variations are healthy. That brown color comes from a pigment called stercobilin, which is produced when your gut bacteria break down bile from your liver. As long as your stool falls somewhere on the brown spectrum, your digestive system is doing its job.
Why Poop Is Brown
The color starts with your liver, which produces bile to help digest fats. Bile contains a yellow-green compound called bilirubin, a byproduct of old red blood cells being recycled. When bile enters your intestines, bacteria get to work on that bilirubin using a specific enzyme called bilirubin reductase. This enzyme transforms bilirubin into a colorless compound called urobilinogen, which then oxidizes further into stercobilin, a dark orange-brown pigment. Stercobilin is what gives feces its characteristic color.
This process depends on two things working properly: your liver producing and releasing enough bile, and your gut bacteria being present to do the chemical conversion. When either of those is disrupted, stool color changes.
Foods That Change Stool Color
Diet is the most common reason your poop looks different from one day to the next. Chlorophyll, the pigment in green plants, passes through your digestive system and can turn stool bright green. Spinach, kale, broccoli, avocados, and matcha are frequent culprits. This is completely harmless.
Beets contain a red pigment called betanin that can make stool look blood-red, which alarms a lot of people who forgot what they ate the night before. Blueberries contain pigments that can turn stool dark blue, deep green, or even near-black if you eat enough of them. Carrots, sweet potatoes, squash, and pumpkin are loaded with beta-carotene and can give stool an orange tint. Cherries, tomatoes, grapes, and plums can shift things toward red or purple.
Artificial food dyes are surprisingly powerful. Brightly frosted cupcakes, rainbow candy, or drinks with heavy coloring can produce vivid, unnatural-looking stool. If you eat enough mixed colors, they can even combine to produce black. Black licorice does the same thing on its own.
Medications and Supplements
Iron supplements commonly turn stool dark green or black. This is a well-known side effect and not a sign of bleeding. Bismuth subsalicylate (the active ingredient in Pepto-Bismol) reacts with trace sulfur in your digestive tract and can turn stool jet black. Some antibiotics tint stool yellow or green by disrupting the gut bacteria that normally produce stercobilin. In all of these cases, the color change is temporary and resolves when you stop taking the product.
Green Stool
Green poop is one of the most common color variations, and it’s almost always harmless. Beyond green vegetables, it can happen when food moves through your intestines faster than usual. Bile starts out green before bacteria convert it to brown, so if transit time is short (during a bout of diarrhea, for example), bile doesn’t get fully processed and stool stays green. Stress, a stomach bug, or anything that speeds up digestion can cause this.
Yellow, Greasy, or Pale Stool
Yellow stool that looks greasy, floats, smells worse than usual, or appears bulky and foamy points to fat malabsorption. This means your body isn’t properly digesting and absorbing the fat in your food. The undigested fat makes stool lighter in color, looser in texture, and noticeably more foul-smelling. Common causes include celiac disease, chronic pancreatitis, and an intestinal parasite called Giardia.
Pale, clay-colored, or putty-colored stool is different and more specific. It means bile isn’t reaching your intestines. Your liver releases bile salts into your stool, and without them, the brown pigment never forms. This can happen when gallstones block the bile duct, when the bile ducts are narrowed or scarred, or when a liver infection reduces bile production. Clay-colored stool that persists for more than a day or two deserves prompt medical attention because it signals a problem in your biliary system, the drainage network connecting your liver, gallbladder, and pancreas.
Black or Tarry Stool
If you haven’t taken iron, bismuth, or eaten blueberries, black licorice, or dark-colored foods, black stool is a red flag. Black, sticky, tarry stool with a distinctly foul smell is called melena, and it typically indicates bleeding in the upper digestive tract (the esophagus, stomach, or first part of the small intestine). The blood turns black because digestive enzymes break it down as it travels through the gut. It takes only about a half cup of blood to produce this effect. This is a medical emergency.
Red or Bloody Stool
Bright red blood in or on your stool generally comes from the lower digestive tract, meaning the colon or rectum. Small amounts are often caused by hemorrhoids or small tears near the anus. Larger amounts can indicate diverticulosis, abnormal blood vessels in the colon, polyps, or inflammatory conditions. Rectal bleeding is the single most common symptom of early-onset colorectal cancer, appearing in roughly 45% of cases, and is associated with at least a five-fold increase in risk. Persistent or recurring rectal bleeding, even small amounts, should not be dismissed as “just hemorrhoids” without proper evaluation, especially if it comes with abdominal pain, unexplained weight loss, or a change in bowel habits.
Normal Stool Colors in Babies
Newborn stool follows its own color timeline. In the first day or two, babies pass meconium: a black-green, sticky, tar-like substance that built up in the intestines before birth. This is completely normal and clears within a couple of days.
After that, stool color depends largely on how the baby is fed. Breastfed babies typically produce mustard-yellow, loose, slightly runny stool. Formula-fed babies tend to have darker yellow stool that’s a bit firmer. Formula with added iron can produce dark green stool, which is harmless. Frothy green stool in breastfed babies sometimes happens when the baby switches breasts frequently; feeding until one breast is fully drained before switching usually resolves it.
Once solid foods enter the picture, things get colorful. Green-brown, orange, and various shades of brown all become normal. As toddlers grow, their stool gradually transitions to look more like adult stool. The one color that’s never normal in babies is white or very pale gray, which signals the same bile flow problem it does in adults and needs immediate medical evaluation.
When Color Signals a Problem
Most stool color changes trace back to something you ate and resolve within a day or two. The colors that warrant attention are black (when not explained by diet or supplements), bright red, and white or clay-colored. These three suggest either bleeding or a bile flow obstruction, both of which have identifiable causes that need diagnosis.
Context matters as much as color. A single odd-colored stool after a meal of beets or a handful of supplements is not concerning. Persistent color changes over several days, especially paired with other symptoms like abdominal pain, unexplained weight loss, fatigue, or changes in how often you go, tell a different story. The combination of symptoms matters more than any single bowel movement.