A randomized trial of two levels of iron supplementation and developmental outcome in low birth weight infants.
OBJECTIVE
To investigate the effect of increased iron intakes on hematologic status and cognition in low birth weight infants.


METHODS
We randomly assigned 58 infants to receive formula with 13.4 mg iron/L (normal iron) or 20.7 mg iron/L (high iron). At baseline, discharge, and at 3, 6, 9, and 12 months' corrected age, we assessed anthropometry; infections; red blood cell hemoglobin, catalase, glutathione peroxidase, red blood cell fragility (hydrogen peroxide test), and superoxide dismutase values; plasma malondialdehyde, ferritin, iron, transferrin, zinc and copper levels; and diet intake. Griffiths' Development Assessment was done at 3, 6, 9, and 12 months only.


RESULTS
No statistical differences (P <.05) were noted for weight, catalase or malondialdehyde levels, red blood cell fragility, or Griffith's Development Assessment. Iron intakes were greater in the high iron group except at 12 months. Hemoglobin (high iron, 123 +/- 9; normal iron, 118 +/- 8) was not different at 3 months (P =.07). Plasma zinc levels (high iron, 70 +/- 14; normal iron, 89 +/- 27) and copper levels (high iron, 115 +/- 26; normal iron, 132 +/- 27; P =.06) at 12 months suggested inhibition of absorption by high iron formula. Glutathione peroxidase levels were higher in the high iron group. The total number of respiratory tract infections was greater in the high iron group (3.3 +/- 0.9) than in the normal iron group (2.5 +/- 0.9).


CONCLUSIONS
In terms of cognitive outcome, there is no advantage associated with elevated iron intake for low birth weight infants.
Friel
J K
JK
Department of Biochemistry, Memorial University of Newfoundland, Janeway Child Health Centre, Grace General Hospital, St John's, Newfoundland, Canada.
Andrews
W L
WL
Aziz
K
K
Kwa
P G
PG
Lepage
G
G
L'Abbe
M R
MR
D000704:Analysis of Variance; D002657:Child Development / Q000187:drug effects*; D003071:Cognition / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007501:Iron / Q000008:administration & dosage / Q000627:therapeutic use*; D015032:Zinc / Q000097:blood
D007501:Iron; D005979:Glutathione Peroxidase; D015032:Zinc