From Mayoclinic.org
Stool comes in a range of colors. All shades of brown and even green are considered normal. Only rarely does stool color indicate a potentially serious intestinal condition.
Stool color is generally influenced by what you eat as well as by the amount of bile — a yellow-green fluid that digests fats — in your stool. As bile pigments travel through your gastrointestinal tract, they are chemically altered by enzymes — changing the pigments from green to brown.
Consult your doctor if you're concerned about your stool color. If your stool is bright red or black — which may indicate the presence of blood — seek prompt medical attention.
| Stool color | What it may mean | Possible dietary causes |
|---|---|---|
| Green | Food may be moving through the large intestine too quickly, such as due to diarrhea. As a result, bile doesn't have time to break down completely. | Green leafy vegetables, green food coloring, such as in flavored drink mixes or ice pops, iron supplements. |
| Light-colored, white or clay-colored | A lack of bile in stool. This may indicate a bile duct obstruction. | Certain medications, such as large doses of bismuth subsalicylate (Kaopectate, Pepto-Bismol) and other anti-diarrheal drugs. |
| Yellow, greasy, foul-smelling | Excess fat in the stool, such as due to a malabsorption disorder, for example, celiac disease. | Sometimes the protein gluten, such as in breads and cereals. But see a doctor for evaluation. |
| Black | Bleeding in the upper gastrointestinal tract, such as the stomach. | Iron supplements, bismuth subsalicylate (Kaopectate, Pepto-Bismol), black licorice. |
| Bright red | Bleeding in the lower intestinal tract, such as the large intestine or rectum, often from hemorrhoids. | Red food coloring, beets, cranberries, tomato juice or soup, red gelatin or drink mixes. |
