Association between full breastfeeding, timing of complementary food introduction, and iron status in infancy in Germany: results of a secondary analysis of a randomized trial

Purpose Considering the low content in breast milk breastfed infants might be at particular risk for depleted iron stores after the first months of life. This study evaluates the association of the mode of milk feeding and the timing of complementary food (CF) introduction with parameters of iron status in term healthy infants in Germany. Methods In this secondary analysis of a randomized controlled trial, parents recorded all foods consumed by their infants from the age of 8 weeks onwards. Mothers were advised on the German food-based dietary guidelines for infants. Accordingly, CF was introduced between the fifth and seventh month of age. Blood samples were taken at 4 and at 10 months of age for analyses of iron status parameters. Iron depletion was defined as serum ferritin <12 ng/mL. Results The iron intake was lower in breastfed infants ( n = 50) than in formula fed ( n = 23) with decreasing differences during the course of infancy. At 10 months of age, most iron parameters were not associated with the mode of milk feeding or the timing of CF introduction. At this age, the iron depletion prevalence was >34% without general differences according to the mode of milk feeding or the timing of CF introduction. Conclusion The high prevalence of depleted iron stores observed in both breastfed and formula-fed infants illustrates the need for further studies to improve our understanding of the optimal iron intake and sensitive parameters of iron status in infancy.