Nitrogen and fat balances in very low birth weight infants fed human milk fortified with human milk or bovine milk protein.

The study was designed to compare two different human milk fortifiers in a group of very low birth weight (VLBW) infants by analysing nitrogen and fat balances, serum concentrations of alpha-amino-nitrogen, urea, and prealbumin as well as growth rates when human milk enriched with one of the two studied fortifiers was fed to the infants. Fortifier A contained different bovine proteins, peptides and amino acids and had an amino acid composition comparable to that of the nutritional available proteins in human milk, with carbohydrates, and minerals. Fortifier B was composed of freeze-dried skimmed human milk and minerals to achieve a similar macronutrient composition in both fortifiers. Eleven infants were fed with human milk enriched with fortifier A and 13 with fortifier B. After a 10-day equilibration period, a 3-day metabolic balance was performed. On the 14th day of the study blood was obtained preprandially for serum analysis and growth rates were estimated. The nitrogen absorption rate (93.8% vs 93.5%) as well as the retention rate (80.8% vs 78.5%) were no different between the groups. The fat absorption rate (92.3% vs 91.5%) as well as the weight gain (32.1 vs 31.1 g/day) were similar and there were no differences in the serum parameters studied. The results indicate that feeding VLBW infants with human milk enriched with a well-balanced bovine fortifier fulfil their nutritional requirements as well as diets composed exclusively of human milk protein.