Stool Color Change
Stool and its color can tell us quite a lot about health of an individual. It is the final waste product of our digestive tract and it is therefore no surprise that a number of diseases influence the coloration of feces.
This is normal colored stool. The brown color is present due to bile pigments in the stool (especially products of bilirubin pigment). We can not, of course, say that a person with brown color of feces has a healthy digestive tract, but it is more likely than by other stool colors.
Light colored stool is usually caused by more or less lack of bile pigments in faeces. It is usually associated with diseases of liver, gallbladder and biliary tract. More information is present in article about pale stool.
This stool consistency and color is classically associated with impaired absorption of fat that is referred to as steatorrhea. There are a number of reasons of fats malabsorption. Usually it is a part of general malabsorption disorders occurring in diseases of liver, gallbladder, biliary tract, pancreas or small intestine. More can be found in the text about fatty stools.
This can be a very dangerous condition. Black stool can be naturally colored by food (e.g. large amount of blueberries) or by charcoal and iron supplements. However, if it is diarrheal foul smelling black stool, it is probably so-called melena. Melena is a result of bleeding into upper part of the digestive tract anywhere between pharynx and upper part of the small intestine. This condition requires immediate medical examination!
Green stool (especially if it is diarrheal) usually occurs in intestinal infections such as salmonellosis. Solid green-black feces are typical for iron supplements. Green stool is also normal in newborns.
We should rather talk about the red ingredient in the stool. It may be a food effect (tomato paste, food colorings, etc.), but often it is red blood in stool. It is professionally referred to as enterorrhagia and it means a gastrointestinal bleeding occurring somewhere between the lower part of the small intestine and rectum. The most common causes are hemorrhoids; other causes are mentioned in text about blood in the stool.