Phytates in fiber reduce non-heme iron absorption
Whole grains, legumes, and high-fiber plant foods contain phytates and oxalates that bind non-heme iron, reducing absorption by up to 50%. Vegetarians and vegans need ~1.8× more iron as a result.
Take iron supplements between meals, or with vitamin C which overrides the phytate-binding effect.
Take iron at least 1-2 hours away from high-fiber meals
Phytates in fiber reduce non-heme iron absorption. Take iron supplements between meals, or with vitamin C which overrides the phytate-binding effect.
Take iron at least 1-2 hours away from high-fiber meals
This interaction is rated “Caution” by Formulate. Whole grains, legumes, and high-fiber plant foods contain phytates and oxalates that bind non-heme iron, reducing absorption by up to 50%. Vegetarians and vegans need ~1.8× more iron as a result.
Studies from our registry that mention fiber or iron. Each links to the primary source and the other Formulate pages citing it.
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.
Mentions iron · 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.
Mentions fiber · 2005
Acetyl-L-carnitine for the treatment of diabetic peripheral neuropathy: a long-term, randomised, double-blind, placebo-controlled study
Sima AA, Calvani M, Mehra M, Amato A · Diabetes Care
52-week RCT (n=1,257) found ALCAR 1000mg three times daily improved vibration perception, sural nerve fiber regeneration, and pain scores in diabetic peripheral neuropathy.
Mentions iron · 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.
Other interactions to know
Calcium significantly reduces iron absorption
Iron reduces levothyroxine absorption
Fluoroquinolones and tetracyclines chelate iron
Zinc and iron compete for absorption
Fiber can reduce medication absorption
Fiber can reduce mineral absorption
Antacids significantly reduce iron absorption
PPIs reduce non-heme iron absorption
Check your full stack in the free interaction checker.
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Medical disclaimer. This page is for educational purposes only and does not replace advice from a qualified healthcare provider.
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