Black farts in stool are related to physiological reasons such as eating too many animal blood products, and may also be related to pathological reasons such as gastrointestinal bleeding and inflammatory bowel disease, as follows. 1. Physiological reasons: if you eat too much animal blood products, drugs containing iron, melanin-rich foods, etc., accompanied by intestinal flora disorders, there will be black farts in the stool. 2. Pathological causes (1) Gastrointestinal bleeding: Gastrointestinal bleeding caused by peptic ulcer, erosive hemorrhagic gastritis, biliary tract injury, etc. If the bleeding is not large, coupled with impaired digestive function, it will lead to the appearance of black farts in stool. (2) Inflammatory bowel disease: if you suffer from Crohn’s disease, ulcerative colitis, patients may have mucus, pus and blood stools, black stools, the disease itself affects the digestive function, resulting in food staying in the gastrointestinal tract for too long, generating gas to cause excessive farts. There are more causes of black farts in the stool, it is recommended to consult a doctor for a clear diagnosis in time to avoid adverse effects.