Supplement Label Index

Ferrous Fumarate vs. Ferrous/Iron Bisglycinate Chelate

Among 1,931 on-market iron products with an identifiable primary form, 60.8% use Ferrous Fumarate (1,174 products) and 15.2% use Ferrous/Iron Bisglycinate Chelate (293).

Ferrous FumarateFerrous/Iron Bisglycinate Chelate
Quality tierUnratedTier 1
Iron by weight32.9%27.4%
Share of market60.8%15.2%
On-market products1,174293
Median declared dose18 elemental mg
middle half: 8–26
10 elemental mg
middle half: 6–18
Most common brandsDC, Wonder Laboratories, GNC Women's Ultra MegaBluebonnet, Solgar, MegaFood

Doses are declared per serving in elemental mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).

Why Ferrous Fumarate is unrated

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

Why Ferrous/Iron Bisglycinate Chelate is tier 1

Apparent bioavailability 90.9% vs. 26.7% for ferrous sulfate in a 40-child matched-group trial of iron-deficiency anemia (not stated as randomized); only the chelate group showed a significant ferritin increase.

Source: Pineda O, Ashmead HD. 2001, Nutrition 17(5):381-384, PMID 11377130

Tiers summarize published comparative bioavailability or outcome evidence for each form (see methodology). This page describes the market; it is not a recommendation to take either form. Talk to a clinician about what's right for you.

Other iron comparisons