Vitamin C dramatically enhances iron absorption
Vitamin C can increase non-heme iron absorption by 2-3x by converting iron to a more absorbable form and counteracting absorption inhibitors.
Take iron with vitamin C for maximum absorption.
Take together
Vitamin C dramatically enhances iron absorption. Take iron with vitamin C for maximum absorption.
Take together
This interaction is rated “Synergy” by Formulate. Vitamin C can increase non-heme iron absorption by 2-3x by converting iron to a more absorbable form and counteracting absorption inhibitors.
Studies from our registry that mention both iron and vitamin c. Each links to the primary source and the other Formulate pages citing it.
Both substances · 2010
Iron bioavailability and dietary reference values
Hurrell R, Egli I · American Journal of Clinical Nutrition
Reviews enhancers (vitamin C, meat) and inhibitors (phytate, polyphenols, calcium) of non-heme iron absorption, providing the mechanistic basis for pairing iron with vitamin C and separating it from tea/coffee.
Both substances · 2000
Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability
Hallberg and Hulthén · American Journal of Clinical Nutrition
Foundational model for non-heme iron absorption factoring vitamin C, phytates, tannins, and calcium interactions.
Mentions iron · 2017
Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women
Stoffel NU, Cercamondi CI, Brittenham G, et al. · Blood
Landmark absorption study showing iron supplements taken daily (or twice-daily) trigger hepcidin elevation that blocks subsequent absorption — supporting alternate-day dosing as more efficient for iron repletion.
Roundup
Best Vitamin C Supplements 2026: Form, Dose, and What Actually Works
Ascorbic acid, buffered, liposomal, or whole-food? Dose by goal (daily health, acute illness, iron absorption, collagen). What the Linus Pauling megadose narrative got wrong.
Guide
Iron Supplements Guide 2026: Evidence-Based & Ranked
Learn who needs iron supplements, what bloodwork to get, and which forms won’t wreck your stomach. Covers dosing science most doctors skip.
Other interactions to know
Calcium significantly reduces iron absorption
Iron reduces levothyroxine absorption
Fluoroquinolones and tetracyclines chelate iron
Zinc and iron compete for absorption
High-dose vitamin C may reduce B12 absorption
Antacids significantly reduce iron absorption
PPIs reduce non-heme iron absorption
Phytates in fiber reduce non-heme iron absorption
Check your full stack in the free interaction checker.
The free checker lets you add any combination of supplements and medications at once. The free web app goes further — every stack change surfaces interaction alerts automatically.
Medical disclaimer. This page is for educational purposes only and does not replace advice from a qualified healthcare provider.
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