Bone mineral metabolism in full-term infants fed human milk, cow milk-based, and soy-based formulas
P. S. Venkataraman, H. Luhar and M. J. Neylan
Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
OBJECTIVE--To study the hypothesis that ingestion of a modified soy-based
formula with an improved mineral suspension system may result in bone
mineral content similar to that observed in infants fed human milk or cow
milk-based formulas. DESIGN--Prospective, self-selected group of infants
fed human milk randomized between the two formula-fed groups.
SETTING--University-based hospital nursery and follow-up.
PARTICIPANTS--Fifty-six normal, healthy, full-term infants, free of major
malformations or disorders, including 17 infants fed human milk, 19 infants
fed a cow milk-based formula, and 20 infants fed a soy protein formula were
followed up to 6 months' postnatal age. The soy-based formula studied was
modified to improve the suspendability of the minerals.
INTERVENTIONS--Infants were fed human milk or the study formula for the
first 4 months, at which time beikost was permitted. Infants fed human milk
received vitamin supplementation to provide 400 IU of vitamin D per day.
MEASUREMENTS--Anthropometric variables, serum calcium, magnesium,
phosphorus, alkaline phosphatase, and parathyroid hormone levels were
measured at enrollment, and at 8, 16, and 24 to 26 weeks' postnatal age.
Bone mineral content at the distal third radius site was measured with
single photon absorptiometry at these times. Growth in the infants did not
differ significantly among the groups. There was no significant difference
in serum calcium, magnesium, alkaline phosphatase, or parathyroid hormone
concentrations among the infants during the study. Serum phosphorus was
significantly lower at 8 weeks in the group fed human milk than in that fed
the cow milk-based formula. Bone mineral content at 16 and 24 to 26 weeks
was higher in the group fed the soy-based formula than in that fed human
milk, and bone width was also higher at 16 weeks in the infants fed the
soy-based formula. CONCLUSIONS--Improving the suspendability of the mineral
system in the soy formula results in bone mineralization in infants fed the
soy-based formula similar to that measured in infants fed human milk and
cow milk-based formula. We suggest that the suspendability of the minerals
used is an important variable in the interpretation of the effect of
feedings on the bone mineral status of infants.
