Bloody or tarry stools refer to a stool sample that’s either dark red or black in color. Bloody or tarry stools can indicate bleeding or other injuries in your gastrointestinal tract. You may also have dark, discolored bowel movements after eating dark-colored foods. Notify your doctor any time you have bloody or black-colored stool to rule out serious medical conditions.

Causes of Black, Tarry Stools
Bleeding in the upper portion of your digestive system can cause black, tarry stools. Ulcers or another form of irritation in your esophagus or stomach known as gastritis can cause bleeding. When the blood mixes with digestive fluids, it takes on the appearance of tar.

Certain medications can also lead to black-colored stools. Iron supplements and bismuth-based medications, for example, can darken your stools. Sometimes, serious blood and circulation abnormalities in your digestive system can cause black, tarry stools. These can include the following:
-- Bowel ischemia is a reduction of blood flow to the intestines.
-- Vascular malformation is misshapen veins.
-- Varices are large, protruding veins in the intestines.

Prevention of Bloody or Tarry Stools
You can help lessen the occurrence of bloody or tarry stools by drinking plenty of water and eating lots of fiber. Water and fiber help soften stool, which can ease the passage of stool from your body. Some foods that have fiber include:
-- raspberries
-- pears
-- whole grains
-- beans
-- artichokes