With the exception of newborns and infants, yellow stools rare and can be caused by various digestive disorders and biliary or liver problems. Pancreatic insufficiency and malabsorption system disorder can also be a cause. Usually, yellow stool indicates a serious liver, intestinal, or stomach condition. In infants, it is normal for a change in stool consistency and color. Soft, yellowish, mustard-colored stool is normal.
Yellow colored stool can indicate that food is quickly passing through the digestive tract. Yellow stool can also be found in people with GERD (gastroesophageal reflux disease), a more serious form of gastroesophageal reflux.
Yellow stool can also result from insufficient bile output. Bile salts released from the liver breaks down the food within your digestive system. It also gives stool its brownish color. When bile output is diminished, waste appears yellow. If there is a greater reduction in bile output, the stool loses almost all of its color, becoming pale or grey. If the yellow stool color appears suddenly, a bacterial infection in the intestines may be the culprit.
The pancreas releases enzymes into the intestines to help with the digestion of fat, protein, and carbohydrates. When pancreatic enzymes are not present in the intestine, fat cannot be fully digested. If there is a high enough amount of undigested fat, bowel movement may become a yellowish hue. The stool also appears greasy and has a foul odor. The most common pancreatic diseases that cause yellow stools are pancreatic tumors that block the pancreatic duct through which the enzymes reach the intestines. Yellow bowel movement can also be caused by chronic pancreatitis, typically due to alcohol damage, which destroys the pancreas ability to make enzymes. When the pancreas does not produce enough enzymes for proper digestion, the condition is called pancreatic insufficiency. If both blood and undigested fat is present in the stool, the stool may become silver.
A parasite infection known as giardia, a diarrheal illness caused by a microscopic parasite also produces diarrhea that is yellow in color.
Finally, in some instances, a change in stool color to yellow can be an indication of pancreatic cancer.
Whenever you notice yellow stool, you should immediately contact your physician for diagnosis.