Which Iron Supplement is Best?

With countless iron supplements crowding the shelves, patients are often overwhelmed and unsure which one to choose. Here’s what you need to know.

The most widely used oral iron supplements are ferrous sulfate, ferrous fumarate, and ferrous gluconate, primarily due to their affordability, availability, and effectiveness. Among these, ferrous sulfate is the most researched and frequently used in clinical settings, with proven success in treating and preventing iron deficiency anemia. Keep in mind, guidance from the American Gastroenterological Association supports the use of ferrous sulfate, fumarate, or gluconate due to their comparable efficacy.

Patients frequently express concerns about gastrointestinal side effects such as constipation, diarrhea, nausea, and stomach pain. Remember, the tolerability of oral iron depends on the dose of elemental iron rather than the formulation. While some believe that polysaccharide-iron complex, carbonyl iron, or ferrous bisglycinate may cause less stomach irritation, there is insufficient evidence to support this claim, and these options are usually more expensive.

For patients worried about gastrointestinal side effects, here are a few strategies to consider. Enteric-coated or controlled-release iron may offer better tolerance. Taking iron every other day, especially for those with mild anemia, is supported by clinical studies and may lessen gastrointestinal side effects.

Lastly, while iron is absorbed more effectively on an empty stomach, taking it with food can help minimize side effects. This is because certain dietary components such as calcium, polyphenols, and tannins can bind iron in the gut. If iron needs to be taken with food, patients should avoid consuming it alongside dairy, coffee, tea, or cereals.

To dive deeper into the safety and effectiveness of iron, check out our latest update.