Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
Stool (feces or poop) is the waste product of digestion.
Food mixes with bile from the liver and digestive enzymes from the pancreas allowing protein, carbohydrates, and fats in the diet to be broken down to form a slurry.
This liquid mixture then passes through the small intestine where nutrients are absorbed into the blood stream, and the leftover liquid waste is delivered to the colon.
In the colon, water is absorbed and results in stool formation.
Normal stool contains bacteria and undigested or partially digested food, especially cellulose from plant material, and bile.
Bacteria are capable of breaking down this undigested food for their own personal use, and some of the products of their activity are absorbed back into the body.
There is moderate variation among individuals with respect to stool color, quantity and form; however, changes in color, form,
texture, and quantity can be an indicator of GI health or disease especially if there are changes.
What is the color of normal stool?
Stool (feces) color is most commonly brown. When stool color changes an
person often becomes concerned. The presence of the bilirubin in the bile (a breakdown product of the hemoglobin in red blood cells that are normally destroyed after a useful life of several weeks) is generally responsible for stool color. Bilirubin concentration can vary the color of stool from light yellow to almost black. Changes in the chemical structure of the bilirubin can cause stool to turn green or yellow. Yellow stool also may occur if stool is dilute or there is a reduction in the amount of bilirubin that is produced by the liver. Bacteria and digestive enzymes in the intestine can act on the bilirubin and change its color. Most stool-to-stool changes in color have little meaning. However, some changes, particularly if the changes are consistent over time and not present in only one stool, can be important.
What are the causes of stool color,
texture, and form changes?
Blood in the stool can be bright red, maroon in color, black and tarry, or occult (not visible to the naked eye). Causes of blood in stool range from harmless, annoying conditions of the gastrointestinal tract such as hemorrhoids to serious conditions such as cancer.