Iron and complementary feeding of breast-fed infants

The American Pediatric Society and Health Canada both recommend that iron fortified cereal (most iron unabsorbed) or meat (most iron absorbed) be introduced to all breast-fed infants at six months of age to support iron stores and linear growth. Evidence suggests that the iron contained in these foods, particularly cereal, is not fully absorbed and will collect in the colon with the possibility of free radical generation and intestinal inflammation. Objectives: To assess the safety of the recommended first solid food for exclusively breast-fed infants from a free radical perspective. Methods: Ninety exclusively breastfed infants are being randomized to 1 of 3 feeding groups: iron fortified cereal (FeCer), iron fortified cereal with fruit (FeCF) or meat (M). Urine and stool samples are collected before introduction of study foods (4-5.5 months) and 3 weeks after introduction of these foods to assess: urinary F2 isoprostanes (LC-MS-MS), urinary 8OH-deoxy guanosine, fecal calprotectin (ELISA), reactive oxygen species (ROS-HPLC) and non-heme iron generation (Colorimetric) in the stool, and the fecal microbiome by 16S RNA gene pyrosequencing. Preliminary results are: urinary isoprostanes (base: 10.1+7.2; after feeds 12.8 + 7.6 ng/mg/ml creatinine; n=25) did not differ over time or between feeding groups at either baseline or after feeds. ROS did not differ between groups at either sampling time nor within the FeCF and M group over time, however there was a trend to increased free radical generation in the FeCer group (base: 0.018 + 0.019; after feeds 0.037 + 0.015 RU; n=12; P = 0.087). Conclusion: Our hypothesis was that iron fortified cereals would provide unabsorbed iron that would reduce the ability of the colon to resist oxidative stress and has been supported from this preliminary subset. The newborn breast-fed infant may not cope with large amounts of unabsorbed iron in the colon.