Iron
Of 8,749 on-market iron products in the January 2026 DSLD dump, the median declared dose is 4 elemental mg, and 77.3% list unspecified/undisclosed form as the primary form.
Form share
Of 8,525 products with an identifiable primary form, here is the share held by each form of Iron on the market today.
| Form | Quality tier | n | Share |
|---|---|---|---|
| unspecified/undisclosed form | Unrated | 6,594 | 77.3% |
| Ferrous Fumarate | Unrated | 1,174 | 13.8% |
| Ferrous/Iron Bisglycinate Chelate | Tier 1 | 293 | 3.4% |
| Iron Amino Acid Chelate | Tier 1 | 167 | 2.0% |
| Ferrous Sulfate | Tier 2 | 159 | 1.9% |
| Ferrous Gluconate | Unrated | 138 | 1.6% |
Form share over time
Entry-year breakdown of the top forms, 2012–2025.
Dose distribution
Deciles of declared dose per serving (elemental mg), among 7,548 products with a disclosed amount, against the RDA of 18 and UL of 45.
- 75.4% of products fall below the fairy-dust threshold (12 mg, 20% of the studied low dose).
- 0.8% of products don't disclose an amount because Iron is declared inside a proprietary blend.
By dosage form
By target group
Top brands
Forms explained
Label discloses only "Iron" with no salt form (largest single bucket, ~9,457 rows).
Elemental fraction: 32.9% (FeC4H2O4, anhydrous (fumarate salts don't commonly form stable hydrates))
Widely marketed as comparably bioavailable to ferrous sulfate with less GI upset, but no comparative human absorption study was independently verified.
Source: uncertain -- needs review
If equivalent to ferrous bisglycinate chelate, showed substantially higher apparent bioavailability than ferrous sulfate.
Source: Pineda O, Ashmead HD. 2001, Nutrition 17(5):381-384, PMID 11377130
Elemental fraction: 20.1% (FeSO4 x 7H2O, heptahydrate (classic commercial/OTC form; a dried monohydrate at 0.329 also exists -- check specific labels))
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 pediatric trial.
Source: Pineda O, Ashmead HD. 2001, PMID 11377130
Elemental fraction: 11.6% (Fe(C6H11O7)2 x 2H2O, dihydrate (standard commercial/USP form))
Commonly used clinically as a milder-tolerated alternative to sulfate, but no comparative human bioavailability citation was independently verified.
Source: uncertain -- needs review
Bioavailability depends on food source and matrix, not a fixed stoichiometric ratio.
Elemental fraction: 27.4% (Fe(C2H4NO2)2, anhydrous bisglycinate (theoretical pure-compound value; branded Ferrochel is standardized to ~20% Fe, likely a diluted/standardized powder rather than pure chelate))
Apparent bioavailability 90.9% vs. 26.7% for ferrous sulfate in a pediatric iron-deficiency-anemia RCT; only the chelate group showed a significant ferritin increase.
Source: Pineda O, Ashmead HD. 2001, Nutrition 17(5):381-384, PMID 11377130
Reference values
- RDA (adult): 18 elemental mg — 8mg (men, all ages; women 51+); 18mg (women 19-50)
- Tolerable Upper Intake Level (adult): 45 elemental mg — Based on gastrointestinal distress from supplemental iron salts
- Studied clinical dose range: 60–200 mg
- Stoffel NU et al. 2017, Lancet Haematology 4(11):e524-e533 -- two open-label RCTs in iron-depleted women, 60-200mg elemental Fe; alternate-day dosing increased fractional and cumulative absorption ~35-50% vs consecutive-day dosing.