Iron is an essential trace element that is important for the development, structure, and functioning of the brain. Iron has been both favorably and unfavorably implicated in neuropsychiatric disorders. For example, iron adequacy in pregnancy and early childhood has been suggested to reduce the risk of neurodevelopmental disorders and schizophrenia, but iron mechanisms have been implicated in neurodegenerative disorders, multiple sclerosis, and stroke. Supplemental iron may be indicated to treat restless legs syndrome, akathisia, and pica, but more commonly to treat iron deficiency associated with poor nutrition in major mental illness. Supplemental iron is commonly orally administered but is poorly absorbed by this route. It is therefore necessary to know what improves and what impairs iron absorption. This article explains that, for best absorption, oral iron supplements are ideally dosed as ferrous salts. The dose should be administered in the morning, on a fasting stomach, along with about 100 mg of vitamin C in the form of a tablet, or with a glass of orange or other citrus juice. If neither vitamin C nor citrus juice is available, as a poorer option, iron should be dosed with plain water. Absorption is markedly reduced if iron is administered in the afternoon, or with food such as cereals and other grains, or with beverages such as milk, tea, and coffee. Calcium supplements, antacids, H2 inhibitors, and proton pump inhibitors also reduce the absorption of orally administered iron. Some data suggest that alternate day dosing improves fractional iron absorption as well as reduces adverse effects of treatment. Finally, to reduce the risk of pill esophagitis, iron should be dosed with a full glass of liquid, and the patient should not recline or lie down for at least the next 30-60 min.
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