title: Early programming of the IGF-I axis: negative association between IGF-I in infancy and late adolescence in a 17-year longitudinal follow-up study of healthy subjects.
abstract: BACKGROUND
  IGF-I is a major regulator of growth, influenced primarily by diet in infancy and primarily by GH in childhood. Breastfed infants have lower IGF-I levels compared to formula fed and tend to be shorter. The higher protein content of infant formula has a stimulatory effect on IGF-I production. Conversely, studies suggest that later in childhood, those breastfed are taller and have higher IGF-I levels. Therefore, it has been suggested that the IGF-I axis may be programmed by diet during infancy. The association between IGF-I in infancy and later life is not known.
  
  
  OBJECTIVE
  To examine the association between IGF-I in infancy and adolescence.
  
  
  METHODS
  Infants (109) from the observational Copenhagen cohort study.
  
  
  METHODS
  Serum-IGF-I was measured during infancy (2, 6, and 9 months) and at follow-up at 17 years. Associations were examined by correlation tests and linear regression controlling for gender, breastfeeding, and other covariates. Likelihood ratio test based on residual log likelihood was applied for analysis including all measurements during infancy.
  
  
  RESULTS
  There was an inverse association between IGF-I at 9 months and 17 years (r=-0.39, P=0.014, and n=40). A 1 ng/ml higher IGF-I concentration at 9 months corresponded to 0.95 ng/ml lower IGF-I concentration at 17 years. IGF-I levels at 2 and 6 months were not significantly associated with IGF-I at 17 years, but the estimated directions were negative. These associations were not changed when adjusted for breastfeeding and other covariates except IGF-I at 2 months which was significantly negatively associated with IGF-I at 17 years (P=0.030) corresponding to a 0.96 ng/ml lower IGF-I concentration at 17 years per ng/ml IGF-I at 2 months. Inclusion of all measurements during infancy showed a negative association with 17-year values (r=-0.26, P=0.043, and n=109).
  
  
  CONCLUSIONS
  The results support the hypothesis that the IGF-I axis can be programmed early in life.
authors.affiliation: Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark. ala@life.ku.dk
authors.forename: Anni
authors.initials: A
authors.lastname: Larnkjaer
authors.forename: Helga K
authors.initials: HK
authors.lastname: Ingstrup
authors.forename: Lene
authors.initials: L
authors.lastname: Schack-Nielsen
authors.forename: Camilla
authors.initials: C
authors.lastname: Hoppe
authors.forename: Christian
authors.initials: C
authors.lastname: Mølgaard
authors.forename: Ib M
authors.initials: IM
authors.lastname: Skovgaard
authors.forename: Anders
authors.initials: A
authors.lastname: Juul
authors.forename: Kim F
authors.initials: KF
authors.lastname: Michaelsen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D006128:Growth; D006801:Humans; D007223:Infant; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male
chemical_list: D007334:Insulin-Like Growth Factor I