This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Disease of the pancreas is usually impossible to diagnosticate with accuracy until it is far advanced, and but little can be expected from dietetic treatment. Since the pancreatic juice is on every account the most important of all the digestive fluids, being a universal digestive agent for all foods, and the most vigorous one, its absence or deterioration results promptly in emaciation, which becomes extreme. When the presence of disease of this gland, such as a cyst, is established, it is best to withhold all fats and carbohydrates from the diet. They are not digested in the stomach, and when the pancreatic juice fails, they merely ferment in the small intestine and do positive harm. Milk, pancreatinised meat preparations, beef peptonoids, and egg albumin, with alcoholic stimulants, must constitute the chief reliance for nourishment.
It is of interest to note that the continued presence of fat or oil in the stools is regarded as a strong diagnostic point in favour of the absence of pancreatic fluid. As a positive test this may have some value, but not as a negative one, for if bile is present in normal quantity the fat of food may still be emulsified and, to some extent, absorbed. In a half dozen cases of undoubted pancreatic cyst in which the diagnosis was established by aspiration or autopsy, I have known doses of several ounces of olive oil administered for diagnostic purpose to give no residue in the stools. The absence of fat in the feces does not therefore necessarily exclude pancreatic disease.