Poo refers to the stool, eat buckwheat noodles pull black stool is generally normal, can not rule out other abnormalities such as gastrointestinal bleeding. Soba contains pigment components, if the pigment can not be fully absorbed by the intestine, may be discharged with the stool, resulting in black stool, if there are no other uncomfortable symptoms, it is considered normal, usually 3 to 7 days after the stool will return to normal color. Eating buckwheat noodles black stools may also be the existence of other abnormalities, clinically more common is gastrointestinal bleeding, patients usually have gastric ulcer, portal hypertension and other medical history. Eat buckwheat noodles black stools, you can promptly go to the hospital for routine stool, gastroscopy and other related examinations to rule out gastrointestinal bleeding and other pathologic factors.