High absorption of fortification iron from current infant formulas.

Abstract

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. Bioavailability of isotopically labeled iron (55Fe and 59Fe) 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. 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. Current infant formulas have a high iron bioavailability, which is an appealing argument for lowering the level of iron fortification in these products.