Metabolic and hormonal serum markers in early childhood: Follow-up of a randomized controlled trial during infancy evaluating a modified, low-protein infant formula.

OBJECTIVES

High protein intake during infancy has been linked to accelerated weight gain and increased obesity risk. This study aimed to examine the effects of a low-protein formula during the first 6 months of life on blood metabolic and hormonal markers during early childhood.

METHODS

Formula-fed infants (<45 days) were randomized to receive either a low-protein formula with modified amino acid composition (mLP; n = 90; 1.7 g protein/100 kcal) or a control formula (CTRL; n = 88; 2.1 g protein/100 kcal) until 6 months of age. Breastfed infants served as a reference group (n = 67). Blood samples were collected in cooperating subjects at 1, 2, and 6 years. We measured insulin-like growth factor-1 (IGF-1), IGF-binding proteins (BPs), leptin, glucose, and insulin, and calculated Homeostatic-Model-Assessment-of-Insulin-Resistance (HOMA-IR). Data were analyzed using linear mixed models and linear regression, adjusting for confounders. In addition, results were correlated to priorly published body composition measurement.

RESULTS

Venous blood was collected from 87 (36%), 77 (31%), and 63 (26%) participants at ages 1, 2, and 6 years, respectively. No differences were found in metabolic markers between the formula groups or compared to the breastfed group at any time point. Furthermore, at 6 years of age, a positive correlation was found between some biomarkers (IGF-1, leptin, and HOMA-IR) and body composition measurements, but not all biomarkers showed such an association.

CONCLUSIONS

In this relatively small study, providing a modified, low-protein infant formula during the first months of life did not affect hormonal and metabolic markers during early childhood.