The Association of Formula Protein Content and Growth in Early Infancy: A Systematic Review and Meta-Analysis

This systematic review aimed to examine differences in growth outcomes between breastfed infants and infants fed with formula with different protein/energy ratios during the first six months of life. We conducted a systematic review in the PubMed, Web of Science, and Springer databases. Twenty clinical trials qualified for inclusion. We extracted data about the growth outcomes of infants who were exclusive breastfed or exclusively infant formula fed in the first six months and used a meta-analysis to pool the finding data. We categorized study formulas into four groups according to their protein content: <1.8, 1.8-2.0, 2.1-2.2, and >2.2 g/100 kcal. In the first month of life, growth was not different between formula- and breastfed infants. During 2-3 months of life, growth was faster in infants who consumed formulas with protein contents higher than 2.0 g/100 kcal. After 3 months, formula-fed infants grew faster than breastfed infants. Our meta-analysis indicated that the growth outcomes of infants fed with infant formula with a relatively low protein/energy ratios, compared with that a relatively high protein/energy ratio, were close to those of breastfed infants.

Automated summary

The study found that there was no significant difference in growth between formula-fed and breastfed infants in the early stages of life. However, infants consuming formula with higher protein content grew faster at 2-3 months old. Furthermore, formula-fed infants showed faster growth compared to breastfed infants as time progressed.