title: Timing of the introduction of complementary foods in infancy: a randomized controlled trial.
abstract: OBJECTIVE
  To increase knowledge on iron status and growth during the first 6 months of life. We hypothesized that iron status would be better in infants who received complementary foods in addition to breast milk compared with those exclusively breastfed.
  
  
  METHODS
  One hundred nineteen healthy term (≥37 weeks) singleton infants were randomly assigned to receive either complementary foods in addition to breast milk from age 4 months (CF) or to exclusive breastfeeding for 6 months (EBF). Dietary data were collected by 3-day weighed food records, and data on iron status and growth were also collected.
  
  
  RESULTS
  One hundred infants (84%) completed the trial. Infants in the CF group had higher mean serum ferritin levels at 6 months (P = .02), which remained significant when adjusted for baseline characteristics. No difference was seen between groups in iron deficiency anemia, iron deficiency, or iron depletion. The average daily energy intake from complementary foods of 5-month-olds in the CF group was 36.8 kJ per kg body weight. Infants in both groups grew at the same rate between 4 and 6 months of age.
  
  
  CONCLUSIONS
  In a high-income country, adding a small amount of complementary food in addition to breast milk to infants' diets from 4 months of age does not affect growth rate between 4 and 6 months, but has a small and positive effect on iron status at 6 months. The biological importance of this finding remains to be determined.
authors.affiliation: Unit for Nutrition Research, Landspitali, The National University Hospital of Iceland, University of Iceland, Reykjavik, Iceland. olofhej@landspitali.is
authors.forename: Olof H
authors.initials: OH
authors.lastname: Jonsdottir
authors.forename: Inga
authors.initials: I
authors.lastname: Thorsdottir
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Hibberd
authors.forename: Mary S
authors.initials: MS
authors.lastname: Fewtrell
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Wells
authors.forename: Gestur I
authors.initials: GI
authors.lastname: Palsson
authors.forename: Alan
authors.initials: A
authors.lastname: Lucas
authors.forename: Geir
authors.initials: G
authors.lastname: Gunnlaugsson
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Kleinman
mesh_terms: D000367:Age Factors; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000517:prevention & control*; D001827:Body Height / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D001942:Breast Feeding; D002508:Cephalometry; D004909:Erythrocyte Indices; D005260:Female; D005293:Ferritins / Q000097:blood; D006452:Hemoglobinometry; D006801:Humans; D007055:Iceland; D007223:Infant; D007227:Infant Nutritional Physiological Phenomena / Q000502:physiology*; D019266:Iron, Dietary / Q000008:administration & dosage; D008297:Male; D009751:Nutritional Requirements
chemical_list: D019266:Iron, Dietary; D005293:Ferritins