Ferric orthophosphate

MineralIron

What is it

Ferric orthophosphate (iron(III) phosphate) is an iron compound used as a food fortification ingredient. Compared to ferrous sulfate, it has lower bioavailability but causes less iron-induced flavor changes in fortified products.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Food fortification

Good Evidence

Used to fortify foods where solubility of ferrous salts would cause spoilage or off-flavors.

How it works

Ferric orthophosphate provides iron in the +3 (ferric) oxidation state, which must be reduced to ferrous (+2) before absorption in the duodenum. This extra step makes ferric phosphate less bioavailable than ferrous salts (about 25-30 percent of ferrous sulfate). However, its insolubility makes it useful for fortifying foods that would react badly with more soluble iron forms.

Dosage

Used in fortification at amounts contributing to daily iron RDA (8-18 mg). Not typically used as a stand-alone supplement.

When and how to take it

Consumed as part of fortified food matrix.

Safety

Generally safe at fortification levels. Lower bioavailability means lower acute GI risk per mg.

Who should be cautious

Same as iron - avoid in iron overload conditions.

Interactions

Same as iron in general - reduced by calcium, tannins, phytate; enhanced by vitamin C.

Frequently asked questions

Why is ferric phosphate used in fortified foods instead of ferrous sulfate?⌄

It is less reactive with food matrices (less oxidation/discoloration) but is less bioavailable - a trade-off in fortification chemistry.

References

Ferric orthophosphate on Wikidata — Wikidata link

Ferric orthophosphate (ChEBI:131371) — ChEBI link

Ferric orthophosphate (PubChem CID 24861) — PubChem link

Ferric orthophosphate on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Ferric orthophosphate (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.