[Nitrogen and lipid balances in newborn infants with low birth weight fed lyophilized breast milk of various composition].

Nitrogen and fat balance studies were performed in 6 low birth weight infants (average birth weight: 1465 +/- 128 g) who were alternatively fed 3 types of lyophilized human milk during the 5th through 14th week of life. Feeding group I received human milk (protein content 1.32%). Group II was administered concentrated human milk (protein content 1.69%). Group III received human milk fortified with whey from cow's milk (protein content 1.74%). Group II showed the best results with respect to weight gain, nitrogen balance and blood metabolites. The introduction of whey protein in Group III resulted in higher plasma levels of urea (p less than 0.05), threonine (p less than 0.05), valine (p less than 0.025), isoleucine (p less than 0.01), leucine (p less than 0.02) and lysine (p less than 0.001) compared with Group I infants. Accordingly, plasma levels of alpha-amino-nitrogen were elevated in Group III.