The objective of the study was to assess the tolerance (intake, incidence of spit up/vomit, and stool patterns), bone mineral status, and vitamin D status of healthy, term infants fed one of two partially hydrolyzed bovine whey protein infant formulas from birth to 56 or 84 days of age. The control formula was commercially available and was compared to an experimental formula.

Eighty-nine term infants were enrolled in the study and 74 (83%) completed the study. The control formula had similar vitamin D but lower calcium and phosphorus content and contained palm olein oil and lactose compared to the experi-mental formula. Infants fed the experimental formula exhibited significantly greater serum 25-OH vitamin D levels at 2 months of age, significantly greater bone mineral content as assessed by dual-energy x-ray absorptiometry at 3 months of age and softer stools during the study period compared to infants fed the control formula. No differences were observed between groups for formula intake, incidence of spit up/vomit, anthropometric measurements, or serum concentrations of calcium, phosphorus, skeletal alkaline phosphatase, or parathyroid hormone.

The results suggest that both study formulas are safe but differ in the metabolic response of infants fed the formula. Bone mineral content in these infants reflected differences in levels of nutrients important to calcium between two formulas over the short-term. Long-term implications and clinical relevance of these findings are unknown and require further study. These results provide additional knowledge regarding the typical vitamin D status as assessed by serum 25-OH vit-amin D of healthy term formula-fed infants.