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Title: IRON ABSORPTION IN BREAST-FED INFANTS: EFFECTS OF AGE, IRON STATUS, IRON SUPPLEMENTS, AND COMPLEMENTARY FOODS

Author
item DOMELLOF, MAGNUS - UMEA UNIVERSITY SWEEDEN
item LONNERDAL, BO - UNIV OF CALIFORNIA, DAVIS
item Abrams, Steven
item HERNELL, OLLE - UMEA UNIVERSITY SWEEDEN

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2001
Publication Date: 7/20/2002
Citation: DOMELLOF, M., LONNERDAL, B., ABRAMS, S.A., HERNELL, O. IRON ABSORPTION IN BREAST-FED INFANTS: EFFECTS OF AGE, IRON STATUS, IRON SUPPLEMENTS, AND COMPLEMENTARY FOODS. AMERICAN JOURNAL OF CLINICAL NUTRITION. 2002. v. 76(1). p. 198-204.

Interpretive Summary: The present study was designed to measure iron absorption from human milk in healthy, term, breast-fed infants at 6 mo of age and to repeat the measurement at 9 mo of age in the same infants. To ensure wide ranges of dietary iron intake and iron status, infants received iron supplements or placebo for more than or equal to 6 wks before the measurements. The primary aim was to investigate the influence of iron supplementation on the absorption of iron from human milk. The secondary aim was to study the effects of infant age, iron status, and complementary food intake on iron absorption.

Technical Abstract: Iron supplements are often recommended for older breast-fed infants, but little is known about factors affecting iron absorption from human milk or supplements. We investigated the effects of age, iron status, and iron intake on iron absorption in healthy, term, breast-fed infants. Twenty-five infants were randomly assigned to receive either 1) iron supplements (1 mg · kg-1· d-1) from 4 to 9 mo of age, 2) placebo from 4 to 6 mo and iron supplements from 6 to 9 mo, or 3) placebo from 4 to 9 mo. Infants were exclusively breast-fed to 6 mo and partially breast-fed to 9 mo of age. Iron absorption was assessed by giving 58Fe with mother's milk at 6 and 9 mo. Blood samples were obtained at 4, 6, and 9 mo, and complementary food intake was recorded at 9 mo. At 6 mo, mean (±SD) fractional iron absorption from human milk was relatively low (16.4 ± 11.4%), with no significant difference between iron-supplemented and unsupplemented infants. At 9 mo, iron absorption from human milk remained low in iron-supplemented infants (16.9 ± 9.3%) but was higher (P = 0.01) in unsupplemented infants (36.7 ± 18.9%). Unexpectedly, iron absorption at 9 mo was not correlated with iron status but was significantly correlated with intake of dietary iron, including supplemental iron. Changes in the regulation of iron absorption between 6 and 9 mo enhance the infant's ability to adapt to a low-iron diet and provide a mechanism by which some, but not all, infants avoid iron deficiency despite low iron intakes in late infancy.