Eat blueberries stool may become black, this is because blueberries are rich in anthocyanins, anthocyanins are blue-violet, if you eat a lot of blueberries will make the color of the stool black, generally stop eating 1-2 days after the stool will return to normal color, will not continue to become black. If you do not eat blueberries after the stool also continued to black, and did not consume pig blood, duck blood, blood sausage and blood tonic drugs, should be considered upper gastrointestinal bleeding, need to go to the hospital in time for examination, can do blood and fecal occult blood test, can also do gastroenteroscopy. The regular diet should pay attention to the regularity and moderation, no matter what the food can not be too preferred, food should be diversified and pay attention to reasonable collocation. In short, eating blueberries black stool is a normal phenomenon, do not worry too much.