Abstract

Background: Estimations of iron absorption from infant formulas are based on 20-year-old data. Data about iron bioavailability from currently used infant formulas are scarce, considering that during the last decades, formulas have had modifications that could affect iron absorption. Methods: Bioavailability of isotopically labeled iron (Fe-55 and Fe-59) from several infant formulas administered to contraceptive-using women between the ages of 30 to 50 years was measured. Six infant formulas and one follow-on formula were compared with a powdered, whole cow's milk, and the results were normalized to an absorption of 40% from a reference dose of iron. Results: Iron bioavailability from the infant formulas was consistently higher (19%), contrasting with the low value (4%) of the unmodified cow's milk (p 0.0001). Iron absorption of the follow-on formula was intermediate (13%). Formulas with 8 mg/l iron and one with 7 mg/l supply approximately 1 mg of absorbed iron, assuming a consumption of 750 ml/day of formula. This amount covers the iron needs of most infants during their period of greatest vulnerability. Formulas containing 12 mg/l iron would allow the absorption of approximately twice the infant iron requirements. Conclusions: Current infant formulas have a high iron bioavailability, which is an appealing argument for lowering the level of iron fortification in these products.