Various types of potatoes. A staple food, or simply a staple, is a food that is eaten routinely and in such quantities that it constitutes a dominant portion of a standard diet for a given people, supplying a large fraction of energy needs and generally forming a significant proportion of the intake of other nutrients as well.
Constipation is defined medically as fewer than three stools per week and severe constipation as less than one stool per week. Constipation usually is caused by the slow movement of stool through the colon.
But bleeding can also cause black, tarry stools or maroon (dark red) stools. Bright red blood usually means bleeding from low in the colon or rectum. Dark red blood usually means bleeding higher up in the colon or small bowel and black tarry stools (melena) is seen with bleeding from the stomach (ulcers, for example).