Iron bioavailability in infants from an infant cereal fortified with ferric pyrophosphate or ferrous fumarate

Background: Infant cereals are commonly fortified with insoluble iron compo unds with low relative bioavailability, such as ferric pyrophosphate, becau se of organoleptic changes that occur after addition of water-soluble iron sources. Objective: Our objective was to compare iron bioavailability from ferric py rophosphate with an alternative iron source that is soluble in dilute acid, ferrous fumarate, and to evaluate the influence of ascorbic acid on iron b ioavailability from ferrous fumarate in infants. Design: Iron bioavailability was measured as the incorporation of stable ir on isotopes into erythrocytes 14 d after administration of labeled test mea ls (25 g dry wheat and soy infant cereal, 100 g water, and 2.5 mg Fe as [Fe -57]ferric pyrophosphate or [Fe-57]ferrous fumarate). Ascorbic acid was add ed to all test meals (25 mg in study 1 or 25 or 50 mg in study 2). Infants were fed each test meal on 4 consecutive days under standardized conditions . The 2 different test meals within each study were administered 2 wk apart in a crossover design. Results: Geometric mean iron bioavailability was significantly higher from [Fe-57]ferrous fumarate than from [Fe-57]ferric pyrophosphate [4.1% (range: 1.7-14.7%) compared with 1.3% (range: 0.7-2.7%); n = 8, P = 0.008]. In thi s study, doubling the ascorbic acid content did not further enhance iron bi oavailability; the geometric means (range) were 3.4% (1.9-6.6%) and 4.2% (1 .2-18.7%) for the test meals with 25 and 50 mg ascorbic acid added, respect ively (n = 9). Conclusion: Iron bioavailability from iron-fortified infant cereals can be improved by using an iron compound with high relative bioavailability and b y ensuring adequate ascorbic acid content of the product.