Eating folic acid may lead to black stools. Folic acid is a B vitamin, and some folic acid has iron added to it, which is excreted along with the stool after eating because the iron is not completely absorbed by the body. After passing through the digestive system, iron reacts with the digestive juices in the intestine and is oxidized to ferrous sulfate. Since ferrous sulfate has a black color, it will affect the color of the stool and the phenomenon of black stools. Black stools from folic acid are normal and do not affect your health, so you do not need to pay special attention to it. For people with more serious symptoms, you can take appropriate digestive drugs, such as stomach and appetite tablets, to improve. The use of digestive drugs can increase the digestion of folic acid in the intestines and promote the absorption of folic acid in the intestines, so it can help improve the symptoms and make better use of the folic acid.