Eating Oreo black stool may be related to dietary factors, gastrointestinal bleeding and other factors. 1. Dietary factors: Oreo cookies are made with chocolate, darker color, not easy to be digested after entering the intestinal tract, which can lead to darker stools and black color after being discharged; or eating Oreos while eating iron, blood products (e.g. duck’s blood), etc., which can also lead to black stools. At this time, after stopping eating about 1~2 days after the stool color can return to normal. 2. Gastrointestinal bleeding: After gastrointestinal bleeding, the oxidation of blood can lead to black stools, which has nothing to do with eating chocolate, and when gastrointestinal bleeding occurs, the problem is more serious and needs timely treatment. When the above situation occurs, you also need to observe whether there are other discomforts in the body, if there are abdominal pain, body weakness, diarrhea and other discomforts, you should go to the regular hospital in time, under the guidance of professional physicians as soon as possible treatment.