The green color of folic acid stool is caused by the iron in folic acid not being completely absorbed, and it should also be alerted to indigestion. Folic acid is a water-soluble B vitamin, and many folic acid tablets also have iron added to them, so when the body takes folic acid supplements, the iron is not fully absorbed by the intestinal system and therefore changes the color of the stool, resulting in a darker stool color, and some people even change to green. The greenish color of stool when taking folic acid is normal as long as it is not accompanied by other symptoms. However, some people are suffering from indigestion. When indigestion occurs, the peristaltic function of the intestines is relatively enhanced, resulting in a shorter retention time of stool in the intestines. The bilirubin in the stool will change to bilirubin due to the oxidation of the acidic environment, so the color is also green, and these people will also have diarrhea.