Trace minerals
Iron
Oxygen transport
Hemoglobin, myoglobin, oxidative phosphorylation.
Upper-limit caution
The Tolerable Upper Intake Level for Iron is 45 mg per day. Routine intakes above this level — counting food + supplements — raise the risk of adverse effects. Multivitamins, fortified foods, and standalone supplements stack faster than people expect.
Forms to avoid
Not all Iron forms absorb equally well. The following forms are commonly used because they're cheap, but their bioavailability is materially lower than alternatives — watch for them on supplement labels:
- ferric oxide
- elemental iron
Formulate's product scoring penalizes these forms when they appear as the primary Iron source — see the methodology page for the rubric.
How Iron appears on labels
Supplement labels list Iron under several names depending on the chemical form used. Any of these on an ingredients panel counts toward your Iron intake:
- iron
- ferrous
- ferrous sulfate
- ferrous fumarate
- ferrous bisglycinate
- ferric
Deep dive
For mechanism of action, dosing protocols, evidence grade, and interaction warnings on Iron, see the full encyclopedia entry:
Iron encyclopedia entry →Related trace minerals
Track your full intake
Formulate's free desktop app aggregates Iron (and ~40 other nutrients) across every supplement in your stack — flagging underdoses, overlaps, and upper-limit overshoots in one view.
Get the appMedical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Targets and upper limits are general adult reference values; individual needs vary by age, sex, pregnancy status, and clinical context.