Digestive residues (fat, nitrogen, sugar, water)

The digestive residues test measures the amounts of fat, nitrogen (as a measure of protein), sugar and the water content in stool. They show how completely food was broken down and absorbed in the small intestine.

How digestion and absorption work together

Fat is dissolved with the help of bile acids and split by pancreatic lipase. Protein is broken down by pepsin from the stomach and by protein-splitting enzymes from the pancreas. Double sugars such as milk sugar are split by enzymes on the surface of the small-intestinal lining. Only the building blocks are absorbed; whatever is left reaches the colon.

Raised digestive residues – what happens in the body?

More fat in stool makes it bulky, shiny and foul-smelling; the fat-soluble vitamins A, D, E and K are lost with it. When more protein reaches the colon, bacteria ferment it into ammonia, indole and iso fatty acids. Unabsorbed sugar is fermented by bacteria – gases and acids are produced, and the sugar binds water in the gut, making stool softer. Possible reasons are lower enzyme output from the pancreas, too few bile acids, a changed small-intestinal lining or very fast gut transit.

Low digestive residues – what does it mean?

Low amounts of fat, nitrogen and sugar are the normal case: food was largely absorbed. A low water content means firm stool and often goes along with slow gut transit.

The interpretation is given in your report.