Iron is an essential mineral that contributes to many important physiologic
functions in the body. Much of the iron in the body is attached to hemoglobin
molecules in red blood cells, thereby delivering oxygen to all of the tissues.
Extra iron is stored in the liver, bone marrow, spleen, and muscles.
Significant deficiency in iron leads to anemia. The most common symptoms of
anemia are weakness and fatigue. Pregnant women, young women during their
reproductive years, and children tend to be at the highest risk of becoming
deficient in iron. Anemia may be mild, moderate, or severe and may be caused by
significant and/or prolonged blood loss such as that from a bleeding ulcer,
menstruation, severe trauma, surgery, or a malignant tumor. It can also be
caused by an iron-poor diet, inefficient absorption of dietary iron, pregnancy,
and the rapid growth that takes place during infancy, early childhood, and
On the other hand, excessive iron in the body can lead to a condition known
as hemochromatosis, which can cause diabetes, liver damage, and discoloration of
Anemia: The most important use of iron supplements is to treat anemia caused
by iron deficiency. This treatment is directed and supervised by a health care
provider, who may first search for the underlying reason for the low levels of
Exercise Capacity Low levels of iron can lead to diminished
exercise capacity, whether anemia is present or not. Therefore, if your iron
stores are low (as measured by your doctor), iron supplements (for example, in a
multivitamin or iron supplement) may improve endurance during aerobic
Attention-Deficit Hyperactivity Disorder (ADHD) Symptoms of
iron deficiency (including decreased attention, arousal, and social
responsiveness) are similar to symptoms of ADHD. There is little scientific
evidence, however, that iron supplementation in those who are deficient improves
behavior in children with ADHD. Since iron can be toxic in children who are not
deficient, there is little justification for its supplementation as a treatment
for ADHD in children with normal levels of this mineral. If iron levels are low,
a healthcare provider can determine whether replacement is needed.
Cough associated with ACE inhibitor use
One preliminary study suggested that iron supplementation may soothe and even
prevent cough associated with a class of medications known as
angiotensin-converting enzyme (ACE) inhibitors (such as enalapril, captopril,
and lisinopril). ACE inhibitors are medications commonly used to treat high
blood pressure and heart failure, but dry cough is a side effect that leads many
people to discontinue their use. Despite this encouraging information, it is
premature to conclude that taking iron with ACE inhibitors to reduce dry cough
is safe or effective.
Plus, it is important to note that taking ACE inhibitors at the same time as
iron may diminish the absorption of this nutrient. Therefore, if used together,
the two should be taken at least two hours apart. Also, iron is associated with
some risk for heart disease. For this reason, it should not be used by
individuals with high blood pressure or heart failure without the consent and
supervision of a physician.
The best dietary sources of iron are liver and other organ meats, lean red
meat, poultry, fish, and shellfish (particularly oysters). Iron from these
sources is readily absorbed in the intestines.
Other sources of iron include dried beans and peas, legumes, nuts and seeds,
whole grains, dark molasses, and green leafy vegetables. However, iron from
these sources must be accompanied by certain nutrients for proper absorption.
For example, vitamin C helps the absorption of this type of iron while calcium
(including all dairy products), bran, tea, and unprocessed whole grain products
block its absorption.
In the U.S. grain products such as breads and cereals are fortified with
Ferrous sulfate is the most common type of iron supplement. Other available
forms include ferrous fumarate, ferrous succinate, ferrous gluconate, ferrous
lactate, ferrous glutamate, and ferrous glycine.
In severe cases of anemia from low levels of iron, or if there is rapid blood
loss leading to iron deficiency, iron and blood will be administered
intravenously in a hospital setting.
How to Take It
Daily dietary recommendations for iron are listed below.
Infants birth to 6 months: 0.27 mg
Infants 7 to 12 months: 11 mg
Children 1 to 3 years: 7 mg
Children 4 to 8 years: 10 mg
Children 9 to 13 years: 8 mg
Males 14 to 18 years: 11 mg
Females 14 to 18 years: 15 mg
Males 19 years and older: 8 mg
Females 19 to 50 years: 18 mg
Females 51 years and older: 8 mg
Pregnant females: 27 mg
Breastfeeding females 14 to 18 years: 10 mg
Breastfeeding females 19 years and older: 9 mg
Because of the potential for side effects and interactions with medications,
dietary supplements should be taken only under the supervision of a
knowledgeable healthcare provider.
The most common side effect from iron supplements is stomach upset including
discomfort, nausea, diarrhea, constipation, and heartburn.
Although not entirely clear, there may be an association between high iron
stores and risk of heart disease, cancer (such as breast cancer), and
Alzheimer's disease. Similarly, for those with inflammatory bowel disease
(Crohn's disease and ulcerative colitis) the areas of the bowel that are
inflamed appear to have higher amounts of iron. This is thought to be because
iron acts as a pro-oxidant, stimulating the damaging effects in the body of
substances known as free radicals.
Iron overload disease, although most commonly an inherited condition called
hemochromatosis, may occur in people who consume excessive amounts of iron over
a long period of time. Symptoms include skin discoloration, diabetes, and liver
damage, amongst other potential complications. The FDA has established that
taking up to 45 mg of iron per day is safe. However, safety for amounts higher
than 45 mg per day is not known. Severe iron overdose occurs when amounts of
iron equivalent to 50 or 100 times greater than the recommended dietary dose are
ingested. Such iron toxicity can lead to destruction of cells in the
gastrointestinal tract, which can cause vomiting, bloody diarrhea, and even
death. Given the severity of potential adverse effects from excessive iron,
supplements should be kept in childproof bottles and out of the reach of
Intravenous iron, administered in the case of severe anemia in a hospital
setting, can lead to headache, fever, swollen lymph nodes, painful joints,
hives, worsening of rheumatoid arthritis, and in rare instances a
life-threatening allergic reaction known as anaphylaxis.
If you are currently being treated with any of the medications discussed
below, you should not use iron without first talking to your healthcare
Iron may interfere with the absorption of many different medications. For
this reason, it is best to take iron supplements at least two hours before or
two hours after taking medications. This is particularly true for the
medications listed below.
The following medications may reduce the absorption of iron:
Cholestyramine and Colestipol: These are two
cholesterol-lowering medications known as bile acid sequestrants.
Medications used to treat ulcers or other stomach problems:
Examples of anti-ulcer medications include cimetidine, ranitidine, famotidine,
and nizatidine. These medications belong to a class of drugs known as H2
receptor blockers. They change the pH in the stomach and subsequently alter the
absorption of iron. It is possible that this effect could occur with other
antiulcer medications including antacids and proton pump inhibitors (such as
omeprazole and lansoprazole).
Iron decreases the absorption of the following medications:
Tetracyclines: These are a class of antibiotics that include
doxycycline, minocycline, and tetracycline.
Quinolones: These are a class of antibiotics that include
ciprofloxacin, norfloxacin, ofloxacin, and levofloxacin.
ACE inhibitors: These are a class of medications used to treat
high blood pressure. Examples include captopril, enalapril, and lisinopril.
Iron may reduce the effectiveness or blood levels of the following
Carbidopa and Levodopa: Iron lowers blood levels of these
medications but it is unclear whether these changes lower the effectiveness of
Levothyroxine: Iron may decrease the effectiveness of this
thyroid replacement hormone. A healthcare practitioner should monitor thyroid
function closely in those taking iron supplements with thyroid medications.
Iron levels may be increased by:
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Review Date: April 2002
Reviewed By: Participants in the review process include: Ruth DeBusk, RD, PhD, Editor,
Nutrition in Complementary Care, Tallahassee, FL; Jacqueline A. Hart, MD,
Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University
and Senior Medical Editor Integrative Medicine, Boston, MA; Gary Kracoff, RPh
(Pediatric Dosing section February 2001), Johnson Drugs, Natick, Ma; Steven
Ottariono, RPh (Pediatric Dosing section February 2001), Veteran's
Administrative Hospital, Londonderry, NH. All interaction sections have also
been reviewed by a team of experts including Joseph Lamb, MD (July 2000), The
Integrative Medicine Works, Alexandria, VA;Enrico Liva, ND, RPh (August 2000),
Vital Nutrients, Middletown, CT; Brian T Sanderoff, PD, BS in Pharmacy (March
2000), Clinical Assistant Professor, University of Maryland School of Pharmacy;
President, Your Prescription for Health, Owings Mills, MD; Ira Zunin, MD, MPH,
MBA (July 2000), President and Chairman, Hawaii State Consortium for Integrative
Medicine, Honolulu, HI.
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