Question: Both of my 2-year old, twin granddaughters had very dark green, almost black loose stools today. Is it something they ate, or is their diet lacking certain vitamins or nutrients? Normally, they are very consistent, although one day last week they were both constipated. At my house, they eat a variety of fresh fruits and vegetables, including broccoli, spinach, carrots, pineapple, bananas, apple sauce, etc.
Dr.Bill: If this is a one-time occurrence, especially if there is no fever, blood in the stool, or pain, then this seems like a harmless problem. Many times children’s stools are affected by what they eat. Other times a simple viral infection can also cause a change in stool color and consistency. A stool’s color normally comes about as a result of the bacteria that are living in our gut. A longer or shorter transition time will affect both color and consistency. If a person is having exceptionally foul smelling stools without any other problem, I usually advise eating yogurt or any food with active cultures/probiotics.

Black tar-like stools may indicate some sort of GI bleed and needs to be taken seriously, especially if associated with pain, fever, and/or lethargy. Also, if a child has prolonged diarrhea lasting two weeks or more, I recommend some sort of work-up to rule out any serious problems. External exposure to poorly cooked/prepared food or river/lake water can cause some serious intestinal infections. These are usually associated with fever, blood in the stool, severe diarrhea and weight loss.

In your situation, I would advise you to watch and see. If your grandchildren develop any of the above mentioned symptoms or act sick, then they should be seen by their pediatrician.