Background: Millions of infants are fed breast milk substitutes, and the type of infant formula can impact weight gain patterns.
Objective: We conducted a randomized controlled trial to determine the direct impact of 2 types of infant formula (cow milk formula, CMF; extensively protein hydrolyzed formula, EHF) on growth and energy balance.
Design: A racially diverse group of formula-fed infants (n = 113) were randomly assigned to either CMF or EHF from the age of 0.75 to 12.5 mo. At each monthly visit, anthropometric measures were obtained to determine growth z scores and weight gain velocity, and to categorize early weight gain patterns as rapid or nonrapid. Also, diet records were collected to determine energy from formula and other sources. Comprehensive assessments of energy balance (intake, expenditure, loss) were made at 0.75, 3.5, and 12.5 mo.
Results: Beginning 3 wk after randomization, CMF infants had significantly higher weight, but not length, z scores than did EHF infants, and this persisted after solid foods complemented the formula diet. On average, weight gain velocity from 0.75 to 4.5 mo was within the range of typically growing infants for both groups, yet velocity was 3.9 g/d greater for CMF infants (P = 0.002), who were more likely to be classified as an early rapid weight gainer, than EHF infants (46% compared with 18%; P = 0.007). Early differences in energy intake and fecal loss, yielding greater energy available for deposition among CMF infants, contributed to the differential weight gain patterns. There were no significant differences between the formula treatment groups in total energy expenditure or sleeping energy expenditure.
Conclusions: Among healthy infants, the type of formula impacted on early rapid weight gain patterns owing to energy intake and loss mechanisms. Research is needed to identify the macronutrients and other compositional constituents in EHF and breast milk that promote satiation and healthy weight gain during sensitive periods of development. This trial was registered at clinicaltrials.gov as: NCT01700205.