Infant formula composition affects energetic efficiency for growth: the BeMIM study, a randomized controlled trial.

BACKGROUND & AIMS Protein source, macronutrient composition and content of long chain-polyunsaturated fatty acids (LC-PUFA) of infant formulae may influence infant growth. We aimed to assess the effect of a modified infant formula on growth. METHODS In a randomized, double-blind trial, 213 healthy term infants consumed isoenergetic study formulae (intervention formula - IF, control formula - CF) from the first month of life until the age of 120 days. IF (1.89 g protein/100 kcal) contained α-lactalbumin (ALAB) and LC-PUFA, while CF (2.30 g protein/100 kcal) provided standard whey and no LC-PUFA. Anthropometry and dietary intake were regularly assessed. A venous blood sample was obtained on day 120. RESULTS Both formulae were well-accepted without significant differences in health related observations. Weight gain was not statistically different between formula groups (IF: 30.2 ± 6.3 vs. CF: 28.3 ± 6.5 g/day, mean ± SD, P = 0.06). Length gain was higher in IF (0.11 ± 0.02 vs. 0.10 ± 0.02 cm/day, P = 0.02). Energy intake from formula was higher in CF at 90 and 120 days (IF: 509 ± 117 and 528 ± 123 vs. CF: 569 ± 152 and 617 ± 169 kcal/day, P < 0.01). Protein intake in CF was significantly higher at each assessment. Growth per energy intake was higher in IF compared to CF for weight (6.45 ± 2.01 vs. 5.67 ± 2.21 g/100 kcal, P = 0.02) and length (0.23 ± 0.08 vs. 0.20 ± 0.08 mm/100 kcal, P = 0.04). CONCLUSIONS The modified infant formula with reduced protein content with added ALAB and LC-PUFA, meets infant requirements of protein for adequate growth. The increased energetic efficiency of the new infant formula might result from improved protein composition by added ALAB. Apparently minor differences in composition can markedly affect energetic efficiency for growth. The study was registered at ClinicalTrials.gov (NCT01094080).