Dark and sticky stools may be caused by dietary factors, gastric ulcer, gastric cancer and other reasons. 1. Dietary factors: Due to the consumption of food such as black rice, mulberry, animal’s blood, etc., black and sticky stools are often caused by the pigment contained in the food, which is usually normal and does not need special treatment. 2. Gastric ulcer: when bleeding is caused by gastric ulcer, iron contained in the blood can combine with hydrogen sulfide in the intestines to form black iron sulfide, which can lead to sticky and black stool. 3. Stomach cancer: As the condition of stomach cancer develops, it will cause the symptom of stomach bleeding, and the blood will be discharged through the digestive tract, which can lead to the symptom of sticky black stool. After excluding dietary factors, you need to go to regular hospital for relevant examination and treatment in time to avoid delaying your condition.