Background & aims: Breastfed infants may be at particular risk for iron deficiency because breast milk is low in iron. In a secondary analysis of data from a complementary feeding trial, indicators of iron status were examined, with particular focus on the development of iron status in those infants who were fully breastfed during the first 4 months of life.
Methods: In this retrospective analysis of data from a randomized controlled trial infants were stratified according to their predominant milk diet during the first 4 months of life, a subgroup of breastfed infants (group BM, n=53) were compared with a subgroup of infants fed (iron-fortified) formula (group F, n=23). Dietary iron intake and indicators of iron status were analysed at 4 months of age (during the full milk feeding period), and during the complementary feeding period at 7 and 10 months of age.
Results: Iron intake was low in the BM group, ranging below the Dietary Reference Intakes throughout the complementary feeding period, with the (estimated) bioavailable iron intake only just achieving the reference requirements. At 4 months, iron deficiency (ID, Ferritin <12.0 ng/mL) was observed in 3 infants in the BM group and in 1 infant in the F group; no infant developed iron deficiency anaemia (IDA, ID and Hb <10.5 g/dl). At 7 and at 10 months of age, iron status was adequate in all infants of the F group. In the BM group, at 7 (10) months of age, ID was diagnosed in 10 (11) infants and IDA was found in 2 (1) infants.
Conclusions: Healthy infants, fully breastfed at 4 months of age, demonstrated ID in about 21% and IDA in up to 6% during the second half of infancy while fed according to the paediatric dietary guidelines. This finding supports the recommendation that supplementation with bioavailable iron via complementary foods should be started early (4-6 months of age) in order to prevent iron deficiency during infancy.
Trial registration: ClinicalTrials.gov NCT00571948.
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