Stools after eating red dragon fruit are usually red in color rather than blackish-green. Due to the different food intake every day, the color of the stool will also be different. Red stool after eating red dragon fruit is a normal physiological phenomenon, this is because red dragon fruit contains a large amount of beet red pigment. After eating red dragon fruit, part of the pigment and dietary fiber is not fully absorbed by the intestinal tract, into the large intestine, and food debris convergence to form red stool. If the stool is blackish green, it may be related to the consumption of chlorophyll-rich foods. However, black-green stools can also be seen in some people with gastrointestinal diseases, gastrointestinal bleeding or long-term constipation. In addition, taking some medications containing iron can also cause the stool to turn black. Patients with black-green stools should consult the hospital in time to find the cause of the disease according to their own recent situation and exclude the interference of dietary factors, so as to avoid delaying the condition.