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.
Recommendation
Take iron supplements between meals, or with vitamin C which overrides the phytate-binding effect.
Timing
Take iron at least 1-2 hours away from high-fiber meals
Sources
— American Journal of Clinical Nutrition
— PMID: 8780333
Frequently Asked Questions
Can I take fiber and iron together?
Phytates in fiber reduce non-heme iron absorption. Take iron supplements between meals, or with vitamin C which overrides the phytate-binding effect.
How should I time fiber and iron?
Take iron at least 1-2 hours away from high-fiber meals
Is this interaction dangerous?
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.
Want to check your whole stack?
The free checker lets you add any combination of supplements and medications at once. Formulate's desktop app goes further — every stack change surfaces interaction alerts automatically.