Relation between protein intake, plasma valine, and insulin secretion during early infancy

During the first 6 months of life the plasma levels of branch-chained amino acids are related to the amount of protein ingested. Thus, the concentrations are lower in breast-fed infants than in artificially fed infants who are on a formula with a protein content which is about 50 per cent higher than in breast milk. At 3, 4 1/2, and 6 months of age the concentrations of valine in plasma and C-peptide in urine and the ratio between C-peptide and creatinine in urine are 2-3 times higher in artificially fed than in breast-fed infants. Plasma valine values correlate significantly with the urinary C-peptide/creatinine ratio. The enhanced insulin response induced by a cow's milk formula is related to the protein content.