Ferrous Sulfate

Ferrous Sulfate is a tier 2 form of Iron, used in 160 on-market products and providing 20.1% elemental iron by weight.

Basis: FeSO4 x 7H2O, heptahydrate (classic commercial/OTC form; a dried monohydrate at 0.329 also exists -- check specific labels)

Why this tier: Reference-standard iron salt used as the comparator in most bioavailability literature; showed lower apparent bioavailability (26.7%) than bisglycinate chelate (90.9%) in one head-to-head 40-child matched-group trial (apparent bioavailability was calculated, not isotope-measured). In a randomized isotope study, ferrous fumarate did not differ significantly from ferrous sulfate in non-anemic women and children.

Source: Pineda O, Ashmead HD. 2001, Nutrition 17(5):381-384, PMID 11377130; Harrington M et al. 2011, PMID 20842166

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