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. Author manuscript; available in PMC: 2009 Nov 1.
Published in final edited form as: Am J Med. 2008 Nov;121(11):943–948. doi: 10.1016/j.amjmed.2008.07.012

Table 4.

Oral iron absorption.

A. Effectors of iron absorption.
Inhibiting iron absorption Facilitating iron absorption

  • Coffee, tea, milk, cereals, dietary fiber, phosphate-containing carbonated beverages

  • Multivitamin or dietary supplements containing calcium, zinc, manganese or copper

  • Antacids, H2 blockers and proton pump inhibitors.

  • Quinolones and tetracycline antibiotics

  • Vitamin C

  • Acidic foods e.g. tomato sauce

  • Non enteric coated iron tablets

  • Fasting ingestion of iron supplements
B. Oral iron absorption test.8
Step 1: Measure morning serum iron level (fasting).
Step 2: Ingest approximately 60mg elemental iron (324 mg ferrous sulphate) with water.
Step 3: After 1-2 hours, measure the serum iron level.
Step 4: Compare the serum iron levels.
Interpretation: An increase in serum iron of >100 μg/dL suggests gut absorption is generally adequate.