Common metabolic profile in infants indicating impaired cobalamin status responds to cobalamin supplementation.
OBJECTIVE
A metabolic profile consistent with impaired cobalamin status is prevalent in breastfed infants. We investigated whether this profile reflects immature organ systems or impaired cobalamin status.


METHODS
In a single-center, randomized, placebo-controlled trial, we studied 107 six-week-old infants. The infants were randomly assigned to receive either an intramuscular injection of 400 mug of cobalamin or no intervention. Concentrations of cobalamin and folate in serum and total homocysteine, methylmalonic acid, and cystathionine in plasma were determined at enrollment and at the age of 4 months.


RESULTS
There were no significant differences between the intervention group (n = 54) and the control group (n = 53) in the concentrations of any vitamin marker at baseline (6 weeks). At 4 months, the supplement-treated infants had a 75% higher median serum cobalamin level and remarkable reductions in median plasma total homocysteine (from 7.46 to 4.57 micromol/L) and methylmalonic acid (from 0.58 to 0.20 micromol/L) levels, whereas levels of both metabolites were essentially unchanged during the follow-up period in the control group.


CONCLUSIONS
Cobalamin supplementation changed all markers of impaired cobalamin status (low cobalamin, high total homocysteine, and high methylmalonic acid levels) toward a profile observed in cobalamin-replete older children and adults. Therefore, the high total homocysteine and methylmalonic acid levels reported for a large fraction of infants reflect not immature metabolism but rather insufficient cobalamin levels to fully sustain cobalamin-dependent reactions fully.
Bjørke-Monsen
Anne-Lise
AL
Department of Clinical Biochemistry, Haukeland University Hospital, N-5021 Bergen, Norway. almo@helse-bergen.no
Torsvik
Ingrid
I
Saetran
Hege
H
Markestad
Trond
T
Ueland
Per Magne
PM
D001942:Breast Feeding; D019587:Dietary Supplements; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007223:Infant; D016014:Linear Models; D008764:Methylmalonic Acid / Q000097:blood; D014805:Vitamin B 12 / Q000097:blood*
D006710:Homocysteine; D008764:Methylmalonic Acid; D005492:Folic Acid; D014805:Vitamin B 12