Green stool can also be caused by taking iron supplements or eating certain foods such as green leafy vegetables. Green stool can also indicate a problem with food digestion due to a disease, disorder or other abnormal process. The normal color of stool or feces is generally light to dark brown. Stool gets its color from bile, which is a yellow-green fluid produced in the liver that helps to digest your food. As food passes through your digestive tract, digestive enzymes break down the bile, resulting in various shades of brown stool.