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United States Department of Agriculture

Agricultural Research Service

Title: The Bioavailability of Elemental Iron Powders Used for Food Fortification Varies among Commercial Forms and Is Influenced by Physiochemistry

item Swain, James
item Newman Jr, Samuel
item Hunt, Janet

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: December 2, 2002
Publication Date: March 14, 2003
Citation: Swain, J.H., Newman Jr, S.M., Hunt, J.R. 2003. The bioavailability of elemental iron powders used for food fortification varies among commercial forms and is influenced by physiochemistry [abstract]. Journal of Federation of American Societies for Experimental Biology. 17(5):A1132.

Technical Abstract: The objective was to determine the bioavailability of six commercial elemental iron powders and how physicochemistry influences bioavailability. The relative biological value (RBV) of the iron powders was determined using a hemoglobin repletion/slope ratio method in weanling, male Sprague-Dawley rats. Powders were assessed physicochemically by measuring iron solubility in 0.02 M hydrochloric acid; surface area by gas adsorption and surface microstructure by scanning electron microscopy. Bioavailability from the elemental iron powders was significantly less than from FeSO4 (100%a): Carbonyl (Ferronyl, U.S.), 64%b; Electrolytic (A-131, U.S.), 54%c; Electrolytic (Electrolytic Iron, India), 46%cd; H-Reduced (AC-325, U.S.), 42%d; Reduced (ATOMET 95SP, Canada), 24%e; and CO-Reduced (RSI-325, Sweden), 21%e (values with different letters significantly differ (p<0.05)). Solubility ranged from 10 to 60% at 15 min and 51 to 97% at 150 min, but the rank/order was inconsistent at different times. Surface area of the powders ranged from 90 to 370 m2/kg. Solubility accounted for 36 to 65%, whereas surface area accounted for 80% of the variation in RBV. Bioavailability of iron powders is less than bakery-grade ferrous sulfate and varies up to 3-fold among commercial forms. Findings indicate that surface area was more predictive of bioavailability than solubility, which was more predictive with time in dilute acid.

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