Effect of Low- and Very Low-Protein Infant Formulas on Overweight and Obesity Between 4 and 72 Months: A Systematic Review and Meta-Analysis

A systematic review with meta-analysis was conducted to evaluate the effects of low- (LPIF, 1.8-1.9 g/100 kcal) or very low- (VLPIF, < 1.8 g/100 kcal) protein infant formulas compared to the current standard (SPIF, 2-2.5 g/100 kcal) in the risk of overweight/obesity between 4 and 72 months of age. The primary outcome was overweight and obesity risk at 4 months of age and the longest follow-up period from randomized controlled trials (RCT) as stated in the original protocol. Risk ratios (RR) and 95% confidence intervals (95% CI) were calculated. Eighteen RCT accounting for 4229 infants were included. The risk for overweight/obesity of VLPIF and LPIF was comparable to that of current SPIF between 4 (VLPIF: RR = 0.91, 95% CI: 0.58-1.43LPIF: RR = 0.95, 95% CI: 0.79-1.14) and 72 months (VLPIF: RR = 1.01, 95% CI: 0.65-1.58; LPIF: RR = 1.05, 95% CI: 0.72-1.51) of age. These results indicate that the early exposition to VLPIF and LPIF is not associated with development of later overweight and obesity. Both formulas represent a safe and effective option for those infants who cannot receive breastfeeding. Furthermore, the reduction of protein content below 1.8 g/100 kcal is still plausible and deserves rigorous research.