If the patient consumes a lot of greens, it may make the stool black. There are a lot of foods in life that can lead to black stools after consumption, such as pig’s blood, duck’s blood, oilseed rape, leeks and other foods, and it is a normal phenomenon to eat these to make the stools black. If the patient eats a lot of greens, it may lead to black stools, but if only a small amount of food, the black stools will not occur. However, black stool may also be caused by upper gastrointestinal bleeding, if the patient exists in the upper gastrointestinal bleeding disease, such as: gastric ulcer, esophagogastric fundic varices, upper gastrointestinal tract tumors and other diseases, will lead to black stool, but these belong to the pathological situation. If the patient consumed oil vegetables black stool, it is best to pay attention to the last two days of the stool condition, if the black stool persists, there may be gastrointestinal hemorrhagic disease, then it is best to go to the hospital for examination and treatment.