Ferrous Fumarate
Ferrous Fumarate is a unrated form of Iron, used in 1,180 on-market products and providing 32.9% elemental iron by weight.
1,180
on-market products
unrated
quality tier
32.9%
elemental fraction
Basis: FeC4H2O4, anhydrous (fumarate salts don't commonly form stable hydrates)
Why this tier: Widely marketed as comparably bioavailable to ferrous sulfate with less GI upset; in a randomized isotope study (57Fe fumarate vs 58Fe sulfate) absorption did not differ significantly in non-anemic Mexican women (17.5% vs 20.5%), infants (7.0% vs 7.2%) or young children (6.3% vs 5.9%). Usefulness in iron-deficient subjects was not established, so no tier is assigned.
Source: Harrington M et al. 2011, Eur J Clin Nutr 65(1):20-25, PMID 20842166