Effect of an α-lactalbumin-enriched infant formula with lower protein on growth.

Background/objectives: Protein concentration is lower in human milk (HM) than in infant formula. The objective of this study was to evaluate the effect of an α-lactalbumin-enriched formula with a lower protein concentration on infant growth, protein markers and biochemistries.

Subjects/methods: Healthy term formula-fed (FF) infants 5-14 days old were randomized in this controlled, double-blind trial to standard formula (SF: 14.1 g/l protein, 662  kcal/l) group (n=112) or experimental formula (EF: 12.8 g/l protein, 662  kcal/l) group (n=112) for 120 days; a HM reference group (n=112) was included. Primary outcome was weight gain (g/day) from D0 to D120. Secondary outcomes included serum albumin, plasma amino acids insulin and incidence of study events. Anthropometric measures were expressed as Z-scores using 2006 World Health Organization growth standards.

Results: A total of 321 of the 336 infants (96%) who enrolled, completed the study. Mean age was 9.6 (±2.9) days; 50% were girls. Mean weight gain (g/day) did not significantly differ between SF vs EF (P=0.67) nor between EF vs HM (P=0.11); however weight gain (g/day) was significantly greater in the SF vs HM group (P=0.04). At day 120, mean weight-for-age Z-score (WAZ) and weight-for-length Z-score (WLZ) did not significantly differ between SF vs EF nor EF vs HM; however the WAZ was significantly greater in SF vs HM (P=0.025). Secondary outcomes were within normal ranges for all groups. Incidence of study events did not differ among groups.

Conclusions: α-Lactalbumin-enriched formula containing 12.8 g/l protein was safe and supported age-appropriate growth; weight gain with EF was intermediate between SF and HM groups and resulted in growth similar to HM-fed infants in terms of weight gain, WAZ and WLZ.