Iron-deficiency anemia is one of the most common nutrient deficiencies, according to the World Health Organization. For some people, increasing the iron in their diet is not enough, and an iron supplement is prescribed. The most common types of supplements are in a form of a ferrous iron salt. The ferrous form of iron is absorbed better than the ferric form. The term elemental iron describes the amount of actual iron available for absorption.
Ferrous Sulfate
This is the most common type of iron supplement prescribed. Iron is bound to a sulfur molecule to form the compound. Ferrous sulfate contains 20 percent elemental iron. For example, a 325-mg tablet will provide 65 mg of elemental iron. It is best to wait 2 hours after eating and take the medication on an empty stomach. Common side effects of ferrous sulfate are constipation, stomach upset and dark stools. The liquid version may also stain teeth.
Ferrous Fumarate
Ferrous fumarate, the type of compound in the commercial brand Hemocyte, is 33 percent elemental iron. A 325-mg tablet will provide 106 mg of elemental iron. The cost is typically higher than ferrous sulfate, but dosing is reduced from three pills to two pills because of the additional available iron per tablet.
Ferrous Gluconate
Ferrous gluconate is formed with iron and gluconic acid. It is only 12 percent elemental iron, so a 325-mg tablet will provide 35 mg of elemental iron. Fergon is a well-known consumer brand. Interestingly, ferrous gluconate is a black dye that is also used as a food additive when processing black olives.
Iron Polysaccharide
Niferex, by Schwarz Pharma, is one brand of iron supplement that uses a polysaccharide iron complex. Capsules are 100 percent elemental iron and are not bound to a salt as the ferrous compounds are. Capsules come in dosages of 50, 100 and 150 mg of iron. The cost for a one-month supply, per the 2001 Red Book for Pharmacists, was 2 to 5 times more than that of ferrous iron salts.
Carbonyl Iron
Carbonyl iron comes in a 50-mg tablet that is taken three times a day. The absorption of carbonyl iron varies, depending upon the production of gastric acid produced in the stomach, which is required to make the mineral soluble. Carbonyl iron enters the blood stream more gradually than other forms of iron because it dissolves more slowly. The cost is comparable to a slow-release tablet of ferrous sulfate, but is significantly more than most forms of iron supplements.
About this Author
Denise Reynolds is a registered dietitian, licensed in both North and South Carolina. She holds a Bachelor of Science degree in human nutrition from Winthrop University. Reynolds writes primarily about health and nutrition topics such as diabetes, heart disease, food allergies, and weight loss, either through lifestyle changes or weight loss surgery.
