Lower protein content in infant formula reduces BMI and obesity risk at school age: follow-up of a randomized trial

Background: Early nutrition is recognized as a target for the effective prevention of childhood obesity. Protein intake was associated with more rapid weight gain during infancy a known risk factor for later obesity. Objective: We tested whether the reduction of protein in infant formula reduces body mass index (BMI; in kg/m(2)) and the prevalence of obesity at 6 y of age. Design: The Childhood Obesity Project was conducted as a European multicenter, double-blind, randomized clinical trial that enrolled healthy infants born between October 2002 and July 2004. Formula-fed infants (n = 1090) were randomly assigned to receive higher protein (HP) or lower protein (LP) content formula (within recommended amounts) in the first year of life; breastfed infants (n = 588) were enrolled as an observational reference group. We measured the weight and height of 448 (41%) formula-fed children at 6 y of age. BMI was the primary outcome. Results: HP children had a significantly higher BMI (by 0.51; 95% Cl: 0.13, 0.90; P = 0.009) at 6 y of age. The risk of becoming obese in the HP group was 2.43 (95% Cl: 1.12,5.27; P = 0.024) times that in the LP group. There was a tendency for a higher weight in HP children (0.67 kg; 95% CI: 0.04, 1.39 kg; P = 0.064) but no difference in height between the intervention groups. Anthropometric measurements were similar in the LP and breastfed groups. Conclusions: Infant formula with a lower protein content reduces BMI and obesity risk at school age. Avoidance of infant foods that provide excessive protein intakes could contribute to a reduction in childhood obesity. This trial was registered at clinicaltrials.gov as NCT00338689.