Supplementation with ascorbic acid (vitamin C) in a dose of 250–500 milligrams twice per day is often recommended to increase iron absorption due to its acidic nature, though it is uncertain whether this ultimately increases the effectiveness of treatment for iron deficiency anemia.[1][2]
Supplementation with high amounts of calcium, zinc, or magnesium in iron deficiency is cautioned against, as these may reduce iron absorption.[3]
In more serious cases of iron deficiency anemia, erythropoiesis-stimulating agents (ESAs) may be used. ESAs are medicines that help the bone marrow to produce red blood cells; they’re often used in conjunction with oral iron therapy for people who also have a condition such as chronic kidney disease that is causing their iron deficiency anemia. Blood transfusions may also be used; they rapidly elevate red blood cells and iron in the body, but this procedure is rare and only used for serious cases of iron deficiency anemia.[4]