How can oral iron absorption be increased?

Strategies to Maximize Oral Iron Absorption

To maximize oral iron absorption, take iron supplements on an empty stomach in the morning with 500 mg of vitamin C, and consider alternate-day dosing rather than daily dosing. 1

Optimal Timing and Administration

• Take iron supplements on an empty stomach when possible, as this maximizes absorption 1
• Administer iron in the morning rather than afternoon or evening, as serum hepcidin levels are naturally lower in the morning 2
• If taking iron with meals is necessary due to gastrointestinal side effects, pair it with meat protein to improve absorption 1
• 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, 3
• Consider alternate-day dosing, which may improve iron absorption compared to daily dosing by allowing hepcidin levels to return to baseline 3

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
• Consuming iron with meat protein enhances absorption 1
• Orange juice (containing approximately 90 mg of vitamin C) can increase iron absorption about 4-fold compared to taking iron with coffee or breakfast 2

Inhibitors to Avoid

• Avoid taking iron with tea or coffee, which can decrease iron absorption by 54-66% due to their polyphenol content 4, 2
• Do not consume iron with calcium-containing foods or medications 5, 6
• Avoid taking iron with fiber-containing foods 5
• Do not take iron with aluminum-based antacids or phosphate binders 5, 6

Iron Formulations

• Standard ferrous iron salts (ferrous sulfate, ferrous fumarate, and ferrous gluconate) are reasonable first choices and typically less expensive 1
• No substantial evidence suggests any one product is better than another in effectiveness or tolerance 1
• If one formulation causes significant gastrointestinal distress, trying a different iron formulation may help reduce side effects 5

When to Consider Intravenous Iron

• Consider intravenous iron if oral iron is not tolerated despite adjustments in dosing and timing 1, 5
• IV iron should be used if ferritin levels do not improve with a trial of oral iron 1
• Patients with conditions that impair iron absorption (inflammatory bowel disease, post-bariatric surgery) may benefit from IV iron 1, 6

Common Pitfalls to Avoid

• Taking iron multiple times per day, which increases side effects without improving absorption 1, 3
• Consuming iron with inhibitors like tea, coffee, calcium, or fiber without vitamin C to counteract the inhibition 4, 2
• Discontinuing therapy prematurely; treatment should continue for approximately 3 months after hemoglobin normalizes to ensure adequate repletion of iron stores 5, 6
• Using multivitamin preparations as the sole source of iron supplementation, as they typically contain insufficient elemental iron for treating iron deficiency 6

By following these evidence-based strategies, patients can maximize iron absorption while minimizing side effects, leading to more effective treatment of iron deficiency and iron deficiency anemia.