Red- or black-colored stool may indicate intestinal bleeding resulting from an anal fissure, hemorrhoids, non-cancerous polyps or colon cancer, notes About.com. A blocked bile duct can cause white- or clay-colored stool, while greasy yellow stool can suggest a fat malabsorbtion disorder such as celiac disease, according to Mayo Clinic.
Hemorroids are swollen or inflamed veins that occur in the lower rectum or around the anus. The condition commonly occurs in pregnant women, aging individuals and those with chronic constipation. Symptoms include a layer of bright red blood on stool, reports MedlinePlus.
The liver releases bile salts that give stool its normal brown color. Conditions that cause a reduction in bile production, such as hepatitis and cirrhosis, and those that cause bile duct blockage, such as gallstones and bile duct cysts, may lead to pale- or clay-colored stool, explains MedlinePlus.