Metabolic consequences of high protein intake in premature infants appropriate for gestational age.

The metabolic consequences of different levels of protein intake were studied in premature infants appropriate for gestational age (birth weight between 1500 and 2000 g) during the third week of life. The different protein intake was the result of different nutrition, human milk and two formulae containing 1.7 and 2.1 g protein/100 ml, respectively. The increasing protein intake causes an increase in the alpha-amino-nitrogen as well as the urea concentration in the serum, an elevation of total and alpha-amino-nitrogen losses in urine, increased amounts of stool accompanied by increased total nitrogen as well as fat excretion. The results indicate that a protein intake of more than 2.5 g/kg X 24 h creates a metabolic overloading without any advantages. Thus, human milk of mothers delivering preterm is a sufficient nutrition for these infants, also with regard to protein requirements, if feeding volumes of 180 to 200 ml/kg X 24 h are tolerated. Supplementation of human milk or nutrition with high protein formulae can be justified only in infants who cannot tolerate sufficient feeding volumes.