title: Effects of different complementary feeding regimens on iron status and enteric microbiota in breastfed infants.
abstract: OBJECTIVE
  To compare iron status in breastfed infants randomized to groups receiving complementary feeding regimens that provided iron from fortified infant cereals or meats, and to examine the development of the enteric microbiota in these groups.
  
  
  METHODS
  Forty-five exclusively breastfed 5-month-old infants were randomized to 1 of 3 feeding groups (FGs)-commercially available pureed meats, iron- and zinc-fortified infant cereals, or iron-only fortified infant cereals-as the first and primary complementary food through 9-10 months of age. Dietary iron was determined by monthly 3-day diet records. Iron status was assessed at the end of the study by measurements of hemoglobin, serum ferritin, and soluble transferrin receptor levels. In a subsample of 14 infants, enteric microbiota were profiled in monthly stool samples (5-9 months) by 16S ribosomal RNA gene pyrosequencing.
  
  
  RESULTS
  Infants in the 2 cereal FGs had 2- to 3-fold greater daily iron intakes versus the meat FG (P < .0001). More than one-quarter (27%) of the infants had a low serum ferritin level, and 36% were mildly anemic, with no significant differences by FG; more infants in the meat FG had a high soluble transferrin receptor value (P = .03). Sequence analysis identified differences by time and FG in the abundances of several bacterial groups, including significantly more abundant butyrate-producing Clostridium group XIVa in the meat FG (P = .01) CONCLUSION: A high percentage of healthy infants who were breastfed-only were iron-deficient, and complementary feeding, including iron exposure, influenced the development of the enteric microbiota. If these findings are confirmed, then reconsideration of strategies to both meet infants' iron requirements and optimize the developing microbiome may be warranted.
authors: Section of Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA.
authors: Nancy F
authors: NF
authors: Krebs
authors: Laurie G
authors: LG
authors: Sherlock
authors: Jamie
authors: J
authors: Westcott
authors: Diana
authors: D
authors: Culbertson
authors: K Michael
authors: KM
authors: Hambidge
authors: Leah M
authors: LM
authors: Feazel
authors: Charles E
authors: CE
authors: Robertson
authors: Daniel N
authors: DN
authors: Frank
mesh_terms: D001942:Breast Feeding; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006801:Humans; D007223:Infant; D007225:Infant Food; D007227:Infant Nutritional Physiological Phenomena; D007501:Iron / Q000097:blood*; D000090463:Iron Deficiencies; D019266:Iron, Dietary / Q000008:administration & dosage*; D054892:Metagenome; D009752:Nutritional Status
chemical_list: D019266:Iron, Dietary; D007501:Iron
keywords: FG; Feeding group; Ribosomal RNA; Soluble transferrin receptor; TDI; Total dietary iron; rRNA; sTfR