Iron Vs. Iron Sulfate As a Supplement

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Iron is a mineral found in every cell of the human body. However, it is rarely found on its own, because pure iron carries a positive electrical charge which makes it unstable. For stability, iron attaches itself to other molecules that carry a negative charge which cancels out its own positive charge. One such example is the sulfate molecule found in iron sulfate, a type of iron supplement that is more commonly known as ferrous sulfate. Iron sulfate contains iron, but it is not pure or “elemental” iron.


Manufacturers prepare iron sulfate by dissolving iron filings in sulfuric acid. Once the iron is completely dissolved, the manufacturer adjusts the pH so it approaches neutral. As this happens, the iron sulfate becomes solid and falls to the bottom of the liquid. The resulting iron salts are then shaped and dried into tablets, syrup or chewable capsules.


Iron sulfate contains 20 percent iron by weight. The standard dose of iron sulfate is one 325 mg tablet one to three times per day. Each tablet contains 65 mg of elemental iron. For children or people who have difficulty absorbing iron, a doctor may prescribe the other forms of iron sulfate, such as syrup or chewable capsules, which come in a lower dose. In each case, the amount of elemental iron corresponds to 20 percent of the dose.


In order to absorb the iron, the hydrochloric acid in your stomach must dissolve the elemental iron from the sulfate molecule in the reverse of the process used to manufacture iron sulfate. To promote this, your doctor may tell you to take iron sulfate on an empty stomach, with a glass of acidic juice such as tomato or citrus juice or with a vitamin C -- also known as ascorbic acid -- supplement.


Most people obtain the iron they require from foods such as meat, poultry, seafood, egg yolks, legumes and fortified grains. You should not take iron sulfate unless your doctor tells you to do so. If he or she does recommend an iron supplement, he or she may recommend iron fumarate or iron gluconate, also known as ferrous fumarate and ferrous gluconate. These are two other types of iron supplements that contain 33 and 12 percent elemental iron, respectively.


Iron sulfate may cause side effects, such as stomach upset, nausea, vomiting, diarrhea or constipation. Ask your doctor what you should do about these. These side effects are often more pronounced with iron sulfate, compared to iron fumarate and iron gluconate. Over time, excess elemental iron may deposit in your internal organs, such as the heart, liver or kidney and joints, where it causes permanent damage. If your doctor tells you to take iron sulfate or another form of iron, always attend all followup appointments and ask when it is safe for you to stop.