[Consequences of the composition of breast milk for the nutrition of underweight newborn infants. II. Lipids and lactose].

The concentrations of fat, lactose and protein were measured in the 24 hour pooled breast milk of 37 mothers delivering preterm (PTM) and of 19 mothers delivering term (TM) from the second to the eighth postnatal day and in addition in the PTM from the third week of lactation. During the 4th week of life the nitrogen retention, the fat absorption rate as well as the energy balance were estimated in 21 very low birth weight infants appropriate for gestational age fed either native PTM (n = 11) or by heating procedures sterilized PTM (n = 10). The concentrations of fat and lactose increase within in the first week of lactation. The concentrations of fat are higher in the PTM during the first 3 days of lactation which results in a higher energy density of PTM during the first days of lactation. At the end of the first week of lactation there are no differences in the energy density between PTM and TM. The fat absorption rate was significantly lower in the infants fed sterilized PTM than in the infants fed native PTM (70.5 +/- 8.4 vs 86.3 +/- 7.4 p.c.). Thus, an energy intake of (70.5 to 8.4 vs 86.3 +/- 7.4 p.c.). Thus, an energy intake of 120-130 kcal/kg.d or an energy absorption of more than 100 kcal/kg.d; respectively, is possible by feeding native PTM as well as TM when feeding volumes of more than 180 ml/kg.d are tolerated. When sterilized breast milk is used or the feeding volume is below 160 ml/kg.d an energy supplementation of the milk is necessary.(ABSTRACT TRUNCATED AT 250 WORDS)