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How to Increase Iron Absorption: What to Eat & What to Avoid
Evidence-based food pairings to maximize iron bioavailability, the biochemical science of gut inhibitors (tannins, calcium, phytates), and strict 2-hour buffer timing protocols.
By Nourish By Nutrients Editorial Team •
Updated: 2026-10-08
Key Evidence Takeaways:
- Co-consuming 100 mg of Vitamin C (ascorbic acid) converts insoluble ferric iron (Fe³⁺) into absorbable ferrous iron (Fe²⁺), boosting bioavailability up to 300%.
- Tannins in coffee/tea and high-dose calcium bind iron in the gut lumen, blocking up to 60–90% of absorption if consumed concurrently.
- Spacing coffee, black/green tea, antacids, and dairy at least 1 to 2 hours away from high-iron meals or iron supplements preserves peak absorption.
- Soaking, sprouting, sourdough fermentation, and cooking in cast-iron cookware actively neutralize phytic acid and deliver bioavailable elemental iron.