Strategies to Maximize Oral Iron Absorption

Optimal Timing and Administration

• Take iron supplements on an empty stomach when possible, as this maximizes absorption 1, 2
• If taking iron with meals is necessary due to gastrointestinal side effects, pair it with meat protein to improve absorption 1, 2
• Avoid taking iron more than once daily, as this increases side effects without improving absorption due to hepcidin elevation that persists for up to 48 hours 1, 2

Enhancers of Iron Absorption

• Add vitamin C (500 mg) to oral iron supplementation to significantly improve absorption, even when taken with meals containing calcium or fiber 1, 2, 3
• Consuming iron with meat protein enhances absorption 1, 2

Inhibitors to Avoid

• Do not consume iron with calcium-containing foods or medications 4, 5
• Avoid taking iron with fiber-containing foods 4
• Do not take iron with aluminum-based antacids or phosphate binders 4, 5

Iron Formulations

• Standard ferrous iron salts (ferrous sulfate, ferrous fumarate, and ferrous gluconate) are reasonable first choices and typically less expensive 1, 2
• No substantial evidence suggests any one product is better than another in effectiveness or tolerance 1, 2
• If one formulation causes significant gastrointestinal distress, trying a different iron formulation may help reduce side effects 4

When to Consider Intravenous Iron

• Consider intravenous iron if oral iron is not tolerated despite adjustments in dosing and timing 3, 4
• IV iron should be used if ferritin levels do not improve with a trial of oral iron 3
• Patients with conditions that impair iron absorption (inflammatory bowel disease, post-bariatric surgery) may benefit from IV iron 3, 5

Common Pitfalls to Avoid

• Taking iron multiple times per day, which increases side effects without improving absorption 1, 2
• Discontinuing therapy prematurely; treatment should continue for approximately 3 months after hemoglobin normalizes to ensure adequate repletion of iron stores 4, 5
• Using multivitamin preparations as the sole source of iron supplementation, as they typically contain insufficient elemental iron for treating iron deficiency 5