The most common causes of iron deficiency anemia in adults are as follows: First, insufficient intake: because some people are picky eaters and partial eaters, causing the body to have an impaired intake of iron, such as lean meat, pig blood, duck blood, pig liver and other substances with a low intake, which in turn causes iron deficiency. Second, blood loss factors: women’s long-term excessive menstrual flow is a very important cause of iron deficiency anemia in adults. Third, bleeding hemorrhoids: Hemorrhoids are also a long-term chronic blood loss process, which is likely to cause iron deficiency. Fourth, digestive diseases: diseases such as peptic ulcers and tumors of the digestive tract cause chronic blood loss, which in turn leads to iron deficiency anemia.