Background/Aim: We have previously shown that infants receiving total parenteral nutrition have low apolipoprotein Al levels which are associated with high-density lipoprotein (HDL) class distributions as in lecithin:cholesterol acyltransferase deficiency. This study investigates the influence of early enteral feedings on apolipoprotein Al and HDL subclasses. Methods: Apolipoprotein Al and HDL distributions were determined in 15 total parenterally fed preterm infants (TPN group) receiving early feedings, in 28 enterally fed preterm infants (ENT group), and in 26 term infants at birth and on day 5. The HDL subclasses were determined by gradient gel electrophoresis. Results: In the TPN group, the apolipoprotein Al levels increased significantly postnatally (from 73 +/- 16 to 104 +/- 23 mg/dl) to levels found in the term and ENT groups on day 5 (88 +/- 16 and 96 +/- 19 mg/dl). The HDL subclass distributions at birth and on day 5 were similar in both TPN and ENT groups with more large HDL2b and less small HDL3c than in term infants. Whereas the HDL subclass distribution of term infants remained unchanged, in TPN and ENT infants, a shift from HDL2b to HDL3c was observed, with no difference between term and preterm infants on day 5. Conclusion: In contrast to exclusively parenterally fed infants, infants receiving early enteral feedings exhibited a significant rise of apolipoprotein Al and HDL subclass distributions as fully enterally fed preterm infants. Copyright (C) 2002 S. Karger AG, Basel.