Stools that are formed, dark yellow in color and regular are the healthiest. Stool is the residue left after the nutrients in food are absorbed, and the observation of stool can help to understand the problems in the intestines. Diseases in the intestines can affect the shape and color of the stool, as well as the regularity of the bowel movements. Healthy stools should come out in long strips, look like bananas, not be too dry and thin, and not be accompanied by abdominal discomfort. The stool is mixed with bile, so it will be stained by bilirubin, which is a dark yellow color, so the color of the stool should be dark yellow. The color of stool is also affected by food. Excessive intake of green leafy vegetables and animal liver may result in green or black stool, but the nature of the stool remains unchanged. Regular bowel movements, once or twice a day or once every two days, are normal. If you have bowel movements more than three times a day or less than three times a week, it is a sign of intestinal problems.