We compared body growth, blood cell counts, and chemistry among infants receiving soy-based formula (SF), breast milk (BM), and casein-based formula (CF).

Full-term neonates delivered at our hospital from June 2001 to August 2003 were recruited and divided into 3 feeding groups (BM=20, SF=19, CF=12) according to the parents wishes. Breast feeding or artificial formulae were given during the initial 3 months of age; thereafter, weaning foods were added freely. Height, weight, head circumference, skin-fold thickness, and mid-arm circumference were measured at birth and 1, 2, 4, 5, 12, and 36 months of age. Cell counts and blood chemistry were analyzed at 5, 12, and 36 months of age.

At 5 months of age, body weight was the lowest in the SF group; the height was similar among all groups. Thereafter, there were no differences in height or weight among the groups until 36 months of age. Hemoglobin was the lowest in the BM group at 5 and 12 months of age ( P <0.05). At 5 months of age, serum cholesterol, BUN, phosphates, and K+ were significantly lower in the SF group; thereafter, all chemical parameters were similar until 36 months of age.

Infants fed with SF showed normal growth during the first 3 years of life as compared to infants fed with BM and CF. Low values of serum phosphates and K+ at 5 months of age in the SF group, despite the high mineral content, suggest that further investigation is needed for effective mineral absorption.