In general, if you eat too many blueberries your stool may turn gray-green. Because blueberries contain anthocyanins and other substances, eating too much of the fruit will cause more anthocyanins to combine with digestive enzymes in the digestive tract and oxidize and decompose, causing the stool to turn grayish green or dark green. This is normal. Or may also be due to eat more blueberries, so that the burden on the gastrointestinal tract increased, the digestive function declined, indigestion caused by the color of the stool turned gray-green. At this time should be appropriate to reduce the intake. When too many blueberries are not cleaned or bad, with bacteria into the body, digestive tract infections occur, may also make the stool color turned gray-green. This is usually accompanied by symptoms such as abdominal pain and diarrhea. When consuming blueberries, it is important to wash them well and not to consume too much of them. When there is a gray-green stool should pay attention to distinguish, whether the shape of the stool changes, there is no abdominal pain, diarrhea symptoms, if abnormal to go to the hospital in a timely manner.