The yellow colour of stool, which is oily and greasy, having a highly unpleasant smell, is a result of irregular fat metabolism. Proper digestion of fats takes place with the help of bile and pancreatic digestive enzyme. When there occurs a lacuna in proper fat digestion and absorption, it may lead to liver disorder, pancreatic and small intestinal problems, and bile dysfunction. This type of stool is greasy or oily; generally, it floats and is bulky. The medical term for this stool is steatorrhea. It may also appear pale yellow to light grey in color, hence stool test is required for confirmation of disease.
Causes of greasy stool
- Disease of gall bladder and biliary tract:
Disorder in proper bile formation and its release into the intestine leads to fat malabsorption. Bile is mainly responsible for fat absorption and activates the function of pancreatic juice to properly act on fat cells. People having the gall bladder removed find it very difficult for fat digestion. Bile is released in small quantity and is unable to cope with a large amount of fat. So, occurs incomplete fat digestion and absorption. It shows an effect on colour and texture of faeces resulting in greasy faeces. Yellow and oily faeces are found in patients suffering from the gallstone, which obstructs the passage of bile flow.
- Disease of pancreas:
Pancreatic disorder too seriously affects fat digestion and absorption. Pancreatitis, acute or chronic severely affects fat metabolism. In this case, pancreatic gland gets transformed into fibrotic tissues, which affect pancreatic enzyme production and release. Cystic fibrosis is another disease of the pancreas, causing secretion of too thick pancreatic juice which gets accumulated, instead of being released causing damage. Pancreatic cancer is also one of the reasons.
- Disease of small intestine:
Disorder in fat metabolism may occur, when there is any error occurring in the small intestine. It is the area where fat digestion occurs. Transport of fats through the lacteals gets impaired. Formation of micelles gets hampered, with small bowel bacterial overgrowth occurs, which is necessary for the absorption of fats in the epithelial lining of the small intestine. Celiac disease and Crohn’s disease severely affects fat metabolism. Surgical removal of a part of small intestine severely affects fat metabolism. Fatty diarrhea may also occur, called Whipple’s disease. So fats may come out in faeces, giving it a greasy appearance.
- Rapid gut transit time:
The transit time of chyme through the gut is fully regulated and controlled, So that digestive enzymes can act on it properly for absorption in intestinal tissues. The increase in transit time may affect digestion and absorption of nutrients especially fats. Diarrhea, short bowel syndrome, possibly irritable bowel syndrome and excessive use of laxatives may disturb transit time.
- Medication:
Greasy stool can occur due to the side effects of consuming excessive weight loss drugs. These drugs suppress fat absorption. These drugs can be consumed along with low-fat diet; otherwise, it can lead to oily diarrhea. Orlistat is a medicine or a diet pill, whose activity is to inactivate the enzyme which digests fats. A small amount of fat is unable to be absorbed in the gut and is excreted out with faeces causing it to be oily and greasy.
- Excess whole nuts in diet:
Greasy faeces may occur, after consuming excess whole nuts, or cashews. This problem does not occur in the case of nuts oil, flour etc. Lipids from whole nuts are very less absorbed.
- Natural fats:
Consumption of jojoba oil contributes a lot for greasy stool. It is least digestible. Eating escolar and oilfish often cause steatorrhea.
- Artificial fats:
Olestra which is a fat substitute leads to the greasy stool. This fat was restructured to hydrogenated form which is not liquid at physiological temperature. Excess consumption of olestra may lead to a loose and greasy stool.
Diagnostic approach
When greasy stool is identified, it is better to find out symptoms associated with it, such as weight loss, abdominal pain, jaundice etc. Stool test becomes compulsory in this case. Liver test finds out disorders in bile juice and blood test indicates an abnormality in bilirubin. Abdominal ultrasound is compulsory in disorder in a biliary system. ERCP is a method to detect disorders in the bile duct and pancreatic duct. It is also useful in the removal of gallstones from the bile duct. When there is a doubt of celiac disease, autoantibodies are examined in blood test and upper GI endoscopy should be performed and biopsy of the proximal small intestine.
Prevention
Diet modification:
Taking least amount of fats in the diet is the best cure of steatorrhea. In the severe case, the person is advised to take gluten free diet. Sometimes vitamin B12 may also be linked to being the cause of this disease, so vitamin B12 rich diet or its supplements should be taken. In certain cases if the cause is due to iron deficiency, then folic acid supplements should be taken.
Alcohol reduction:
Intake of alcohol should be on a reduced and controlled basis. If necessary, consumption of alcohol should be completely stopped.
