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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Dietary Prevention of Obesity-related Disease Research » Research » Publications at this Location » Publication #135852


item Swain, James
item Hunt, Janet

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/31/2002
Publication Date: 2/6/2003
Citation: Swain, J.H., Hunt, J.R. 2003. Elemental iron powder used for food fortification: does physiochemistry predict bioavailability? [abstract]. Report of the 2003 International Nutritional Anemia Consultative Group (INACG) Symposium. February 6, 2003. Marrakech, Morocco. Abstract #95. p.41.

Interpretive Summary:

Technical Abstract: Background: The bioavailability of elemental Fe powders used widely as food fortificants is poorly documented. Rapid, economical measures of bioavailability are needed. Aims: To determine the extent that physicochemistry predicts the bioavailability of six commercially produced (~2001) elemental Fe powders, collected by SUSTAIN (Sharing U.S. Technology to Aid in the Improvement of Nutrition, Washington, D.C., USA). Methods: The relative biological value (RBV) of the Fe powders was determined using the AOAC hemoglobin repletion/slope ratio method in 220 weanling, male Sprague-Dawley rats. After dietary Fe depletion (24 d; ~1.5 mg Fe/kg AIN93G diet), rats consumed a repletion diet (14 d; AIN93G diet) fortified with one of six elemental Fe (all > 97% Fe) powders (each ~12, 24, and 36 mg Fe/kg), ferrous sulfate (FeSO4 H2O; ~6, 12, 18, and 24 mg Fe/kg), or no added Fe (~1.5 mg Fe/kg); n=9-10/diet. Solubility was measured (n=3) in dilute (0.02 M) hydrochloric acid, and assaying Fe in solution at 15 to 150 min time points. Surface area (n=6) was determined by gas absorption (30 mol % helium and 70 mol % nitrogen; BET method). Results: The RBV (FeSO4=100%) of the Fe powders differed significantly (values marked with the same letters are not different (p<0.05)): Carbonyl (Ferronyl, U.S.), 64%a; Electrolytic (A-131, U.S.), 54%b; Electrolytic (Electrolytic Fe, India), 46%bc; H-Reduced (AC-325, U.S.), 42%c; Reduced (ATOMET 95SP, Canada), 24%d; and CO-Reduced (RSI-325, Sweden), 21%d. Solubility also differed, ranging from 10 to 60% at 15 min and 51 to 97% at 150 min, but with an inconsistent rank/order at different time points. Surface area of the Fe powders ranged from 90 to 370 m2/kg, and was more predictive of bioavailability than was solubility at any time: R2=0.80 vs. an increasing R2 of from 0.40 at 15 min to 0.64 at 150 min. Conclusions: The bioavailability of elemental Fe powders differed considerably, and was better predicted by surface area than by solubility.