Red blood cells are needed by the body to transport oxygen to your cells, which your cells need to use glucose efficiently to make energy. If you are anemic, you have too few red blood cells. Although a lack of iron can cause anemia, there are many other different causes of anemia, which means that taking iron supplements may not be able to adequately treat the condition.
Although iron is needed for red blood cells to be made, there are other vitamins that are needed for your body to effectively make red blood cells. Folate and vitamin B12 are two nutrients that are essential for red blood cell production, and a lack of either of these nutrients can result in anemia, the Mayo Clinic explains. As a result, anemia can be caused by a lack of folate or vitamin B12 in your diet; in addition, some people have trouble absorbing dietary vitamin B12, which can result in vitamin B12 deficient anemia.
There are some genetic disorders that can also cause you to be anemic, regardless of your iron intake. Sickle cell anemia, for example, is a disorder caused by genetic mutations in hemoglobin, which is a protein which allows red blood cells to carry oxygen. Patients with sickle cell anemia have increased destruction of their red blood cells, resulting in anemia, KidsHealth.org notes. Other genetic disorders that can cause anemia are thalassemia, hereditary spherocytosis and glucose-6-phosphate deficiency.
A number of other conditions can cause you to be anemic. For example, blood loss, due to heavy menstrual periods or internal bleeding, can cause you to become anemic, even if you take iron supplements. Other conditions, such as ulcerative colitis, rheumatoid arthritis, kidney failure and cancer, can also cause your red blood cell levels to decrease, MedLinePlus indicates. Bone marrow disorders, such as aplastic anemia, can cause your body to be unable to make enough red blood cells.
A number of tests can help you determine why you are anemic, even with iron supplementation. A blood smear allows physicians to look at your red blood cells under a microscope and identify abnormalities in the red blood cells, which can reveal vitamin B12 deficiencies, genetic abnormalities and other diseases that can cause anemia. You may also need to have the B12 and folate levels of your blood tested to see if they are the cause of your anemia.