Supplement Label Index

Ferrous/Iron Bisglycinate Chelate vs. Ferrous Gluconate

Among 1,931 on-market iron products with an identifiable primary form, 15.2% use Ferrous/Iron Bisglycinate Chelate (293 products) and 7.1% use Ferrous Gluconate (138).

Ferrous/Iron Bisglycinate ChelateFerrous Gluconate
Quality tierTier 1Unrated
Iron by weight27.4%11.6%
Share of market15.2%7.1%
On-market products293138
Median declared dose10 elemental mg
middle half: 6–18
9 elemental mg
middle half: 3–17.25
Most common brandsBluebonnet, Solgar, MegaFoodWonder Laboratories, DC, ALLMAX

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/Iron Bisglycinate Chelate is tier 1

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

Why Ferrous Gluconate is unrated

Commonly used clinically as a milder-tolerated alternative to sulfate, but no comparative human bioavailability citation was independently verified.

Source: uncertain -- needs review

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