Acute C‐Peptide, Insulin and Branched Chain Amino Acid Response to Feeding in Formula and Breast Fed Infants

Abstract

The response of C-peptide in serum and urine and of glucose and branched chain amino acids in blood to formula and breast feeding was assessed in six breast-fed and six formula-fed infants 3-6 months of age. We analysed serum C-peptide, branched chain amino acids (BCAA) in blood, and blood glucose in the fasting state at 90' and 180' after a regular meal. The excretion of urinary C-peptide and creatinine was also determined. The formula-fed infants received a formula in current use, containing 15-16 g protein/l and with a casein/whey ratio of 40/60. In the fasting state, no significant inter-group difference was found in the level of serum C-peptide or the valine/glycine ratio. Postprandially, the formula-fed infants had significantly higher serum C-peptide values and valine/glycine ratio than the breast-fed infants, p less than 0.05. No significant inter-group difference was found for blood glucose. The urinary C-peptide/creatinine ratio was significantly lower in the breast-fed group, p = 0.02, and significantly correlated both to the valine/glycine ratio at 90', rs = 0.75, p = 0.02 and to the serum C-peptide value at 90', rs = 0.66, p = 0.03. These results confirm that in formula-fed infants the insulin response to a meal is enhanced compared to that in breast-fed infants. The finding of similar blood glucose values in the two groups may also indicate an insulin resistance in the formula-fed infants following a meal.