Plasma amino acid and protein concentrations in infants fed human milk or a whey protein hydrolysate formula during the first month of life.

The aim of the study was to compare growth parameters, biochemical indices of protein metabolism and plasma amino acid concentrations in infants fed either human milk (n = 12) or a whey protein hydrolysate formula (n = 13) during the first month of life. Growth and gain in skin fold thickness were similar in both groups whereas serum protein concentration was significantly decreased (57.4 +/- 3.9 versus 61.2 +/- 2.9 g/l) in the infants fed the whey hydrolysate formula. The discrepancies between the plasma amino acid pattern of the whey hydrolysate formula group and that of the human milk group lessened during the first month. Nevertheless, at a mean age of 33 days the plasma threonine concentration remained twice as high and the plasma tyrosine, phenylalanine and proline concentrations were significantly lower in the whey hydrolysate formula group than in the human milk group. Thus, compared with breast-fed infants, growth and most of the biological indices of protein metabolism were satisfactory in infants fed during the first month of life on a whey protein hydrolysate formula. Nevertheless, the decrease in total plasma protein concentration needs to be confirmed in a larger cohort of infants. In addition, further research is necessary to investigate the possible ways of reducing the hyperthreoninemia and preventing other plasma amino acid disturbances since it would be desirable to obtain plasma amino acid levels similar to those of breast-fed infants.