- Foods containing heme iron are the best for increasing or maintaining healthy iron levels. Such foods include (in decreasing order of iron-richness) clams, oysters, organ meats, beef, pork, poultry, and fish.
- Non-heme iron is less well absorbed. About 60% of the iron in meat is non-heme (although meat itself helps absorb non-heme iron). Eggs, dairy products, and iron-containing vegetables (including dried beans and peas) have only the non-heme form. Other sources of non-heme iron include iron-fortified cereals, bread, and pasta products, dark green leafy vegetables (such as chard, spinach, mustard greens, and kale), dried fruits, nuts, and seeds.
Iron supplements can significantly reduce symptoms in people with restless legs syndrome who are also iron deficient. Patients should use them only when dietary measures have failed. Iron supplements do not appear to be useful for RLS patients with normal or above normal iron levels.
Supplement Forms. To replace iron, the preferred forms of iron tablets are ferrous salts, usually ferrous sulfate (Feosol, Fer-In-Sol, Mol-Iron). Other forms include ferrous fumarate (Femiron, FerroSequels, Feostat, Fumerin, Hemocyte, Ircon), ferrous gluconate (Fergon, Ferralet, Simron), polysaccharide-iron complex (Niferex, Nu-Iron), and carbonyl iron (Elemental Iron, Feosol Caplet, Ferra-Cap). Specific brands and forms may have certain advantages.
Regimen. A reasonable approach for patients with RLS is to take 65 mg of iron (or 325 mg of ferrous sulfate) along with 100 mg of vitamin C on an empty stomach, 3 times a day.
IMPORTANT: As few as 3 adult iron tablets can poison, and even kill, children. This includes any form of iron pill. No one, not even adults, should take a double dose of iron if they miss one dose.
Tips for taking iron are:
- For best absorption, take iron between meals. (Iron may cause stomach and intestinal disturbances, however. Some experts believe that you can take low doses of ferrous sulfate with food and avoid the side effects.)
- Always drink a full 8 ounces of fluid with an iron pill.
- Keep tablets in a cool place. Bathroom medicine cabinets may be too warm and humid, which may cause the pills to disintegrate.
Side Effects. Common side effects of iron supplements include the following:
- Constipation and diarrhea -- these are rarely severe, although iron tablets can aggravate existing digestive problems such as ulcers and ulcerative colitis.
- Nausea and vomiting may occur with high doses, but you can control this by taking smaller amounts. Switching to ferrous gluconate may help some people with severe digestive problems.
- Black stools are normal when taking iron tablets. In fact, if they do not turn black, the tablets may not be working effectively. This tends to be a more common problem with coated or long-acting iron tablets.
- If the stools are tarry looking as well as black, if they have red streaks, or if cramps, sharp pains, or soreness in the stomach occurs, bleeding in the digestive tract may be causing the iron deficiency, and the patient should call the doctor immediately.
- Acute iron poisoning is rare in adults, but can be fatal in children who take adult-strength tablets.
Interactions With Other Drugs. Certain medications, including antacids, can reduce iron absorption.
Review Date: 10/15/2010
Reviewed By: Reviewed by: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.