The 2005 Dietary Guidelines for Americans suggests that nutrient needs should be met through the foods we eat whenever possible. However, fortified foods and dietary supplements may be necessary in some cases.
Iron is found in both animal and plant foods in two different forms — heme iron (from animals) and nonheme iron (from plants). When diet alone cannot restore deficient iron levels to a normal range, supplements may be needed.
Iron supplements are generally available in two forms: ferrous and ferric. Of the two, ferrous iron salts like ferrous sulfate and ferrous gluconate are best absorbed by the body. However, the amount of iron absorbed by the body decreases as the size of the dose increases. The U.S. Centers for Disease Control suggest that people taking an iron supplement space the dose out, rather than take it all at once.
Side effects of using an iron supplement can include:
- Nausea and/or vomiting
- Constipation or diarrhea
- Dark colored stool
- Abdominal pain or cramping
The CDC suggests starting with half the recommended dose and gradually increasing to the full dose to minimize side effects.
For adults with iron deficiency anemia, the recommended supplement is fifty to sixty milligrams of elemental iron (the amount of iron that is actually absorbed and usable) twice per day. A 300 milligram dose of ferrous sulfate taken twice daily provides approximately that amount. Three months of an iron supplement is the usual treatment for iron deficiency anemia, but this can vary depending on how an individual responds.
Because iron deficiency is uncommon among adult men and post-menopausal women, these individuals generally don’t need an iron supplement — except under the advice of a physician.
One thing to keep in mind is that iron toxicity is a possibility. The body excretes very little iron — when the body’s normal storage sites are full, iron can accumulate in tissues and organs. According to the Institute of Medicine of the National Academy of Sciences, the tolerable upper iron intake limit for healthy people is 40 milligrams per day for children between one and thirteen. Above the age of thirteen, the tolerable upper iron intake limit is 45 milligrams per day.
In children, taking 200 milligrams of iron has resulted in death. Be careful to keep iron supplements out of the reach of any children.