What happened to eating pig blood and black stool?

Black stools after eating pig blood are generally caused by excessive intake of hemoglobin.

Black stools after eating pig blood are usually a normal physiological phenomenon. Pig blood contains a large amount of hemoglobin. If ingested too much in a short period of time, it will produce more iron-containing compounds after digestion and decomposition by the gastrointestinal tract. After the above iron-containing compounds enter the intestinal tract, they can react with sulfides in the intestinal tract to form ferrous sulfide. After mixing with excreta, they can cause stools to turn black. The stool blackening caused by eating pig blood generally does not last for a long time and usually disappears within 1-2 days after stopping eating.